Wildguzzi.com
General Category => General Discussion => Topic started by: randy yocum on June 27, 2019, 07:37:34 PM
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I recently bought a good used 1997 Ducati 900ss here's what I have done to it so far ,installed a (New) clutch,fuel pump,fuel filter,starter solenoid,cleaned the carburetors twice,including correctly setting pilot screws and balanced both carbs to specs.Both cylinders show gobbs compression 175lbs on both cylinders.Timing is spot on, and both sparks plugs have nice hot blue flames. I've ridden the bike 400 miles in the last couple days ,it starts beautifully,has a nice lopping idle, underway it pulls very strong in any gear till I hit 5000 rpms and the the power drops off.I experimented on the highway in 5th gear at 5000 rpm as the power was dropping off I pushed the choke lever on full and it was like an after burner kicked on.The bike accelerated hard right up to 100mph and I backed off. So its got to be fuel,like I said the carbs are squeaky clean,could the main jet size be wrong? I'm not sure that at 5000 rpm the main jet is even involved.Could the needle in the slide need to be moved up.These are CV's carbs with rubber diaphragms and they are in great shape.The needle is aluminum and is not adjustable I suppose a guy could maybe shim the needle up a little with a washer or two.I just don't know where the problem lies,any Ideas out there? Does anyone recognize this scenario? any help would be appreciated
(https://i.ibb.co/zs7L8Gs/20190625-171737.jpg) (https://ibb.co/zs7L8Gs)
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Electronic ignition with rev. limiter??
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Hi Randy, couple of things.... did the bike come from the same or similar elevation where you are now?? At that rpm your on the main jet and may need to go up a few sizes along with the tweaking the slide opening etc. Stock airbox? Join a Ducati forum specific to the model you have and learn, learn learn. Congrats on the SS. Enjoy!
Paul B :boozing:
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These are the stock Mikuni CV carbs ? I think you gave the clue Randy by mentioning that closing the choke helped . You might also make sure the diaphragms are still pliable and have no holes in them .
Dusty
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Yes,it has the stock air box with a K+N filter ,and factory stock Mikuni carburetors.The bike had been sitting unused for 12 years here in Missouri where I live,so same elevation.
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Double check all vacuum lines and the connectors, internal ports to the diaphragms as thats what controls the slides. Any specs in the factory internals will help too.
Paul B :boozing:
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http://www.factorypro.com/Prod_Pages/prodd09.html
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If its been sitting awhile.....dont ignore the simple stuff.....is the petcock gummed up or not flowing enough, what about the tank vent, make sure its clear....disconnect that anti-spill/check valve gismo on the vent tube. Good luck....nice bike!!
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Hello Randy. Wow. What a pretty bike. I must admit I’m falling more and more in love with my red carby 1996 Ducati 900 SS.
Not sure what to tell you, on account of my Ducati ignorance. Mine pulls stupid strong up to about 7500 or 8000 rpm, then runs out of steam. Like you said about yours, mine starts *instantly* when the button is pushed.
I’m thinking since the problem is resolved with the choke, then it’s not electrical or spark or mechanical or bad gas. Gotta be something with intake manifold, carbs, fuel supply, etc.
I’m pretty sure that at full throttle and 5,000 rpms, you are mostly or entirely on the main jet.
Since it starts and runs well in other conditions, I’m thinking there is not a gross air leak. Is the float bowl height adjusted right? Sounds like it’s fuel starved upon high demand.
I’d also wonder about the CV diaphragm. Does it move freely? And sticking, holes, etc.?
Do you still have this problem if you crack open the fuel cap to ensure there is no vacuum problem?
I’m also wondering about the “choke” or fuel enrichener. Is there maybe a leak or fault in that system such that when you move the handlebar adjuster, it corrects the problem and runs better?
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Randy,
The "choke" is really an "enricher", it puts more fuel into the carbs. If it runs better with the enricher on then for some reason you are starving for fuel. At 5K your probably at 1/2 throttle or so. Fuel lines are pretty tight under the tank between the frame be sure you haven't pinched one. My 900SS had Mikuni flatslides so I'm not real familiar with the diaphram carbs. On mine the fuel pump ran continuously with the overflow fuel returning to the tank. Different system but it worked. Do you have accelerator pumps on your carbs?
Bill
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It’s too bad that there is not a Ducati website that is comparable to WildGuzzi. I’ve looked but haven’t found one.
Which is a backhanded way of saying how wonderful this forum is.
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It’s too bad that there is not a Ducati website that is comparable to WildGuzzi. I’ve looked but haven’t found one.
Which is a backhanded way of saying how wonderful this forum is.
totally agree, I found that out pretty quick with my new Ducati. And the forum is not nearly as active.
VIVA wild Guzzi!
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Might just be some fun reading here....https://www.ducatiforum.co.uk/search/34907513/?q=900ss+carbs&t=post&o=relevance (https://www.ducatiforum.co.uk/search/34907513/?q=900ss+carbs&t=post&o=relevance)
These guys seem to be as close as your going to get to WG. They have some good info in general and I visit once a week or so even tho I have a 907ie and some of the stuff crosses over.
Paul B :boozing:
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Motoguzzibill,you and I have the same carbs, flat slide Mikuni's, the top of the slide has the rubber diaphragm. Here's pictures I took of mine.you can see the rubber diaphragm attached to the bottom of the slide. I assuming these carbs are the constant velocity type ,i'm not an expert but when you open the throttle,your not pulling on the slide like a normal carburetor,your opening a throttle plate like a valve. Here I took this off the internet."The Constant Velocity carburetor has a variable throttle closure in the intake air stream before the accelerator pedal operated throttle plate. This variable closure is controlled by intake manifold pressure/vacuum. This pressure controlled throttle provides relatively even intake pressure throughout the engine's speed and load ranges."
(https://i.ibb.co/zJZ7vBr/20190608-155329.jpg) (https://ibb.co/zJZ7vBr)
(https://i.ibb.co/4WQPgPK/20190608-080558-2.jpg) (https://ibb.co/4WQPgPK)
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I'm not sure that at 5000 rpm the main jet is even involved.
I would imagine it is very involved. :smiley: Even the idle jet is a little involved. You are in the area of needle/orifice, though.
It's probably ignition. :evil: :smiley: A weak spark needs a very rich mixture.. <shrug> Don't ask me how this has been pounded into my thick skull.. more than once.
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Does the SS have a vacuum fuel pump like my 96 Monster ? Check the two CV chamber vent hoses from the sides of the carbs for kinks or improper routing.. There's also a common fuel bowl vent hose between the carbs, check that also....
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It’s too bad that there is not a Ducati website that is comparable to WildGuzzi. I’ve looked but haven’t found one.
Which is a backhanded way of saying how wonderful this forum is.
concur on both counts
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totally agree, I found that out pretty quick with my new Ducati. And the forum is not nearly as active.
VIVA wild Guzzi!
yeah, I'd like a little bit of crossover regarding 937 Testaretta engines (SS, HM, MS) and software. Notchy neutral, cold clutch, oil consumption, breather reed valve, muffler valve, TSU setting, etc. Lots of guys just spitballing it.
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Kinda though WG is the Ducati forum .
Dusty
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I bought my 96 900 Monster about 4 years ago..I ran ok but had the often mentioned problems with the stock CV Mikunis..I got some info from the various sites but many said the stock carbs are junk and put on a set of very expensive Keihins.. I keep messing with the Mikunis, changing float levels and jetting. I removed the stock airbox to make pulling carbs easier...I put on large K&N pods instead and was told the engine will never run correctly...I was told by some that messing with float levels was wrong....
After some frustration but persistence I got the engine running perfectly with the pods... It does not run lopey at low speeds like many Ducatis, I can cruise along smootly at a steady 2500 rpm in town..The engine responds cleanly to the throttle and pulls to over 8000 rpm on an accurate tach...
In the long run you often have to tune the engine the way it wants to be tuned and not what others may do...
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I recently bought a good used 1997 Ducati 900ss here's what I have done to it so far ,installed a (New) clutch,fuel pump,fuel filter,starter solenoid,cleaned the carburetors twice,including correctly setting pilot screws and balanced both carbs to specs.Both cylinders show gobbs compression 175lbs on both cylinders.Timing is spot on, and both sparks plugs have nice hot blue flames. I've ridden the bike 400 miles in the last couple days ,it starts beautifully,has a nice lopping idle, underway it pulls very strong in any gear till I hit 5000 rpms and the the power drops off.I experimented on the highway in 5th gear at 5000 rpm as the power was dropping off I pushed the choke lever on full and it was like an after burner kicked on.The bike accelerated hard right up to 100mph and I backed off. So its got to be fuel,like I said the carbs are squeaky clean,could the main jet size be wrong? I'm not sure that at 5000 rpm the main jet is even involved.Could the needle in the slide need to be moved up.These are CV's carbs with rubber diaphragms and they are in great shape.The needle is aluminum and is not adjustable I suppose a guy could maybe shim the needle up a little with a washer or two.I just don't know where the problem lies,any Ideas out there? Does anyone recognize this scenario? any help would be appreciated
(https://i.ibb.co/zs7L8Gs/20190625-171737.jpg) (https://ibb.co/zs7L8Gs)
My buddy and I both had carbed '97s. We installed Factory Pro jet kits (with more tapered needles than stock) after a few thousand miles and the bikes ran great. Over time, the bikes seemed to run richer and richer and we couldn't understand why. I went to flat slides, but my buddy didn't. After a while, he discovered that the Factory Pro needles were wearing out the needle jets, causing the bike to run richer. Factory Pro denied they were the cause, but began providing plated or harder needle jets. The weird thing is that the other years didn't seem to be affected. In any case, the issue was resolved after he installed the new jets, and returned the carb settings to the factory pro specs.
Does your bike have the original needles, and what do the needle jets look like? How many miles are on it?
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To check or confirm that you are indeed running lean and not rich, have someone follow you to see what happens at 5000 rpm. If rich you will see some black smoke. If lean you will get popping. The choke circuit is obviously fixing it, but that doesn't mean that it's lean. Hope you find the issue.
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Thanks everyone for your insight and suggestions,as to jpv7's questions,the bike has only 13,000 miles and the slide needles look brand new,I can't detect any wear,which surprises me because the are made of aluminum.I still think the problem is not enough fuel.My friend an auto mechanic suggested I try shimming the slide needle up, a couple thin washers should do the trick ( these needles don't have the graduated grooves like many have).Then test it and see if it behaves better.It won't cost anything but my time,I will report back soon with my results .
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Thanks everyone for your insight and suggestions,as to jpv7's questions,the bike has only 13,000 miles and the slide needles look brand new,I can't detect any wear,which surprises me because the are made of aluminum.I still think the problem is not enough fuel.My friend an auto mechanic suggested I try shimming the slide needle up, a couple thin washers should do the trick ( these needles don't have the graduated grooves like many have).Then test it and see if it behaves better.It won't cost anything but my time,I will report back soon with my results .
The slide needles won't wear. While you are in there, take a close look at what they are going into - the needle jet. That was our problem.
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Outside thought. When you had the carbs open....did you check to see if rubber diaphragms had any holes or wear. They are old.
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Did you have this problem above 5,000 rpm before you did anything to the carbs? That's a potentially important clue. If these same carbs weren't doing this before you got into the carbs, but are doing so now, you probably induced a fault somehow when you were working on the carbs.
I've pondered this, and I strongly suspect that there is something wrong with the CV slide. At lower speeds, the other jets, and maybe a partially opened slide, flow enough gas mixture for the engine to run ok. But when you want lots of power above 5,000 rpm, you can't get enough gas mixture because the slide won't rise up far enough.
So I'm thinking there is probably a vacuum leak of some sort. Are the gaskets properly in place? Everything snug? Or maybe there is some crud in the mechanism that prevents free motion.
Sounds like you can spray propane from an un-lit propane torch all around the outside of the carbs while the engine is running. If there is a vacuum leak, the propone will get sucked in and the engine speed will increase, confirming the existence and location of the leak.
If you take the carbs off again, I'd look to see if there is a way to apply a vacuum to the correct area to see if the CV slide moves freely, and fully, to the top. I've never seen these carbs up close and personal, so I'm not sure if that's feasible.
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I posted the link to Factory Pro jet kits and carb rebuilds above. (if that turns out to be the issue)
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When I got the bike it had been sitting in dry storage unused for several years.I discovered the fuel pump and starter solenoid didn't work,the tank was pretty clean with no rust.The bike wouldn't start so I pulled the carbs they were dirty but easily cleaned .The rubber diaphragms attached to the flat slides looked really good and pliable.So to answer SmithSweed I don't know if this is an old problem or new,because I have no history on the bike.I like your idea of using a porpane gas around the carb area while the engine is idling to find out if there is a vacuum leak.I like your idea of attaching some form of vacuum to the carb to watch the motion of the slide. I've never heard of anyone doing this ,I would like to see a video of someone doing it to one of these mikuni carbs.I wouldn't know where to attach a vacuum line to induce the slide to rise,cool idea though. You know these bikes are unique in that you can easily raise the tank up exposing the air cleaner,battery,electrics.great idea.Anyway remove the air filter and your looking straight down at the carbs in the airbox,with the slides right in your face.Start the engine and you can see the slides and the throttle plate move as you turn on the throttle.The thing is my mechanic friend told me the vacuum slides won't behave the same with the bike sitting in neutral in my garage as they would under load going down the highway,too bad it would be an easy way to test if they are working correctly.
I've got company coming in this weekend,I spent the day getting ready for them so I haven't had a chance to do anymore with the bike .It will have to wait till next week.Thanks again to everyone for your help.
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Yep! I love the pivoting gas tank and how easy it is to get access to everything. Brilliant design.
In my opinion, the diagnostics totally change since you don’t know the history of the bike before messing with the carbs. Could be wrongly sized jets, improperly adjusted screws, who knows what. I’d go back to stock everything.
Here’s another idea. If you take the carbs off again, why not drain the float bowls to get rid of all the gas, then experiment with putting the hose of a powerful shop vac on the engine side of the carbs. Not sure how much vacuum a shop vac can induce, but I’ve got one that seems pretty sucky. Then play with the throttle plate and see if you get good smooth motion of the slide. You should be able to see this action from the intake side.
Alternatively, maybe run a leaf blower into the intake side and inspect slide action from the engine side. I’m less sure that would work since the engine side may not see enough vacuum in the open.
There should be a passageway on the engine side that “sees”
the engine vacuum, and it communicates that vacuum up into the slide diaphragm. Is that passageway blocked? Meanwhile look for any potential leaks in this system.
As to your mechanic friend’s suggestion of raising the jet. Seems like that might work, certainly if the prior owner had it too low. But I’d be somewhat worried that it might merely mask the problem by raising the needle, when the real problem could be that the entire slide isn’t raising up completely.
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Randy:
The stock carbs are Mikuni BDST 38mm CV. These were used on many other bikes, such as the Yamaha XTZ 750 Super Tenere and the TDM 850. So maybe other bike forums would have diagnostic information, and a Yamaha dealer could supply parts.
Looks like you can buy a pair of new Mikuni carbs for about $600. I suppose that is the guaranteed fix.
I have confirmed that the “choke” on this bike is a separate enrichment circuit that draws fuel from the float chamber through its own jet. So it adds more fuel (as opposed to restricting air). Seems to me the most important clue is that the bike runs fine if you give it “choke,” i.e. more fuel above 5000 rpm. Which I think means spark is fine, there is enough fuel reaching float chamber, etc.
Here are the OEM specs according to my Haynes manual. Since you don’t know what the prior owner may have done, I’d suggest confirming that you have all stock parts and if not, replace with the stock unit.
Main Jet is 140
Main air jet is 70
Needle jet is Y-2
Jet needle is 5C19, with clip set at 4th notch from bottom
Pilot jet is 42.5
Pilot air jet is 60/1.4
LT Synder manual suggests that you stick your finger into the carb body and push the slides up. You should hear the vacuum suck, and both slides should feel exactly the same.
The Synder manual also shows a small O-ring underneath the diaphragm cover. I bet that O-ring is easily lost or overlooked, and a likely source of vacuum leaks.
Finally, I’d make double darn sure the carbs are fully seated into the rubber intake manifold boots, and there aren’t any splits or cracks there, and everything is snug and tight. Synder says to “push them home,” which suggests to me it’s possible to put them only part way in.
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Randy, I have a complete set of carbs from a 900 Monster. I not saying they are better than yours, but I'll sell them for a reasonable price if you want spare parts....
I bought a new set on Ebay a few years ago...$360 because they were for a 750...Just change the jets and it's identical to the 900 carb...
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I had to reread your original post. What have you done to make sure of the same flow of air in both carbs? In other words what have you done to synchronize the carbs? and their flow of air at idle & at higher rpm's?
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I don't know anything about Ducati's, but I had a fuel starvation issue with my 1996 Suzuki GSXR1100. It turned out that the fuel tank's petcock on the GSXR1100 is activated (opens or closes) by the vacuum drawn on the petcock as the engine rpm's increase. The last owner of my bike, after installing a racing carb set, removed the vacuum line and plugged the petcocks vacuum port since the new carburetor set didn't have a vacuum port, which kept the petcock maybe 1/4 - 1/2 way open at all times. My bikes engine would bark down at random, sometimes when riding faster, and other times at very low speeds, or it sometimes wouldn't start at all.
I removed the factory vacuum operated petcock and replaced it with a free flowing racing petcock, which fixed all of my bikes issues. I would also check to see on how much fuel is actually making it through the petcock (if it is a free-flow). Maybe your petcock needs to be rebuild?
Make sure that your petcock's fuel tank filter is clean.
(https://i.ibb.co/cwSk65m/h9ahv1-EQQBe6-B-BLh-Bx-Q.jpg) (https://ibb.co/cwSk65m)
Make sure that if you have a vacuum port, it is actually hooked up to something, unlike mine, which was plugged......
(https://i.ibb.co/1nDtdW8/fullsizeoutput-21804.jpg) (https://ibb.co/1nDtdW8)
This was my fix. I installed a free-flow racing petcock
(https://i.ibb.co/dLQqJnq/s-l1600.jpg) (https://ibb.co/dLQqJnq)
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What Andy says above,^^^^^^ most or all Ducati's of 90's had a vacuum operated petcock...I have heard complaints about them....Mine was ok but I replaced it with a manual petcock..
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But remember from my original post when I apply full choke at 5000rpm the bike takes off like rocket and will continue on till I roll the throttle off and release the choke.To me there is no problem with fuel delivery to the float bowls.I will try shimming both needles in the slides tomorrow,well see what happens.Now Rough Edge Racing said he uses a size 150mm main jet in his carbs and they work great.I checked and my carbs have the stock 140mm jets,maybe I need those larger jets?:violent1:
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A ‘97 900SS has a manual petcock. After you get the carb problems figured out and are riding the bike, to prevent future problems it’ll be a pretty good idea to shut off the petcock and drain the float bowls when the bike will be sitting for more than a couple of weeks. The drain screws are easily accessible on a half fairing bike, one with a screwdriver and the other with an 8-mm or 5/16 inch open end. Drain hoses from each carb route the fuel to an area adjacent to the side stand.
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Rough Edge---I agree with you. If you engage the "choke" and the bike runs fine for an extended period of time, then I think that proves fuel delivery to the float bowls is adequate. The choke circuit is just adding extra fuel which the engine obviously needs, and it is getting it from the float bowls. Therefore the main jet could also supply that missing fuel, but for some problem.
Personally, I still suspect the slides aren't raising up all the way, and/or there is some kind of vacuum leak.
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Rough Edge---I agree with you. If you engage the "choke" and the bike runs fine for an extended period of time, then I think that proves fuel delivery to the float bowls is adequate. The choke circuit is just adding extra fuel which the engine obviously needs, and it is getting it from the float bowls. Therefore the main jet could also supply that missing fuel, but for some problem.
Personally, I still suspect the slides aren't raising up all the way, and/or there is some kind of vacuum leak.
Yes , the added fuel is masking a lean condition , probably caused by an intake leak . If the main jets are stock size , and the motorbike is otherwise stock , it should at least run clean to redline . Going up one size on the main might make it run a little better , but you are still simply masking the underlying problem .
Dusty
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Don't assume that just because the jets, etc., are the correct numbers that they ARE correct.
I chased a vicious off-idle richness on my MilleGT for a long time because the atomizers (needle jets for you Amal guys) had been drilled out.
Right numbers, wrong size.
This particular example obviously doesn't apply in the OP's case, because his situation is an apparent leanness at WOT, but the principle still applies.
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I tried my idea of shimming the slide needle up ,but had disappointing results,the original setup is one .5mm washer I added a 1mm washer to that at first seemed to make no difference,then added another 1mm washer for a total of 2.5mm and the bike acted poorly at 3000 rpm and didn't help my original problem at all at 5000rpm.I switched back to the one .5mm washer,so I'm back to square one.Everyone talks about an intake leak,I tried everything I can think of to find it,The propane bottle trick as the engine is running,and I tried spraying ether with a long straw to direct the spray in different areas of the carbs to see it the engine would speed up at idle if I found the leak,No luck.I have a question about those vent hoses that come off the carburetors ,there are 3 of them why are they there?I mean if were talking vacuum leaks seems like if they are open vents to the atmosphere ,that could be a possibility for air leaks. I wish I had an extra set of known good carbs to try, is there a good place to buy parts for these carburetors?I might try larger main jets next.
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I tried my idea of shimming the slide needle up ,but had disappointing results,the original setup is one .5mm washer I added a 1mm washer to that at first seemed to make no difference,then added another 1mm washer for a total of 2.5mm and the bike acted poorly at 3000 rpm and didn't help my original problem at all at 5000rpm.I switched back to the one .5mm washer,so I'm back to square one.Everyone talks about an intake leak,I tried everything I can think of to find it,The propane bottle trick as the engine is running,and I tried spraying ether with a long straw to direct the spray in different areas of the carbs to see it the engine would speed up at idle if I found the leak,No luck.I have a question about those vent hoses that come off the carburetors ,there are 3 of them why are they there?I mean if were talking vacuum leaks seems like if they are open vents to the atmosphere ,that could be a possibility for air leaks. I wish I had an extra set of known good carbs to try, is there a good place to buy parts for these carburetors?I might try larger main jets next.
Does the bike have the charcoal canister in place, or has it been removed? Both our '97s came with them. We removed them, but I can't remember the plumbing, sorry. But it is worthwhile to verify.
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Hi There! try removing the K&N filter and installing an original Flat slide carbs react poorly if there isn't enough "draw" in the airbox. A GSXR suzuki with the airbox lid removed will not come off idle it will just backfire from the lean condition created. Ducati engineers spent a lot of time balancing the air intake to the carbs, the K&N may be causing issues. As previously stated if you can add fuel with the enrichner / choke circuit and it doesn't starve it isn't a fuel delivery issue. Shimming the Needles will only change the mixture at one point on the needles taper, CV carb slides are only fully open at high vacuum at roll on they drop to maintain constant airspeed in the venturi and return to approx mid way once the air speed has stabilized (hence the name constant velocity) The wearing needle jet is fairly common Dyna Jet needles cause the same condition they are harder than the jet so the jet becomes the sacrificial part. If you can't or won't replace the K&N a quick and dirty test is to tape off the air inlet 30% and see if things improve. As with all testing make some careful notes of "everything" you do lots of odd problems drag on because of details missed in the early stages of trouble shooting. FWIW
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The easiest thing it get a Factory jet kit. Various jets, washers and rings will be there to rebuild and dial-in the carbs. Those kits used to be $100.
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These things will run with aftermarket airfilters... This is my 96 Monster 900....This engine runs flawlessly from idle to over 8000 rpm. There is no hesitation or flatspots.. The engine runs cleany for a Ducati at low rpm and you can cruise through town at 2500 rpm in third gear with almost no lope...about 42 MPG...
The hose in the middle of the air filters is the common carb vent...Around the battery you can see a steel/rubber line, there is one on each side from the carb vacuum chamber vents to the rear of the battery, dead air space...Performance Pro needle and nickle plated needle jets, stock #40 pilot jet, #150 main jet. most important, the float is set to 14mm on the rectangular shaped float half...5/16 fuel line with manual petcock,, stock vacuum fuel pump....
(https://i.imgur.com/n5npj69h.jpg)
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Thanks again everyone for your kind assistance in try to resolve my problem.To answer the last few questions,there is no charcoal canister on the bike it was removed by a previous owner.
That's an interesting notion about getting to much air flowing to the carburetors ,Here's a picture of my air box as you can see a opened space with a K+N filter verses what I assume is a normal stock, air box with much of the area is closed off except for those snorkels,I took this picture off of the internet.I will definitely try duck taping a good portion of the air box off to see if it makes a difference.I've got nothing to lose.
(https://i.ibb.co/NFtGCf1/20190702-112950.jpg) (https://ibb.co/NFtGCf1)
(https://i.ibb.co/JnBPvZm/s-l1000.jpg) (https://ibb.co/JnBPvZm)
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Randy, at the time the instructions I remember from Factory Pro were to remove the snorkels only from the lid of the box with the K&N. But I recall others having the lid removal set up without having issues. Its worth a try, but I doubt that taping a portion off will make a difference.
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Too much air to the carbs? The engine will only take in as much as it can volumetrically handle.
Its the air/fuel mixture that has to be correct. An engine cannot take in too much air.
This sounds like a main jet that is too small.
My Cal III when I got it would not pull red line WFO. Pulled the main jet it was a 130. Bumped it to a 142 and it pulled like the UP Big Boy. Looking at the plugs I think a 145 would be better.
A few years later it stopped pulling high rpm. It acted as if it hit a rev limiter. Doing a normal tune up I pulled the stock air filter to clean it. It was like a rock. Replaced it and really put a whopping on my friends with the Road Star and Low Rider Sport that had been worked on.
I could pull ahead of em before the work. They swore I did something to the engine.
I think a bigger main will cure it.
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Hallelujah It's fixed!!!just got back from a 40 mile ride ,2 lane ,twisties and interstate,Wow! what a difference,it runs beautiful. Thankyou,Thankyou To one and all, who helped me figure this crazy problem out .
Today mcmuck provided the final piece to this puzzle I needed, with his posting,here is part of it; Posted by: mcmuck
« on: Today at 08:53:31 AM » Insert Quote
(Hi There! try removing the K&N filter and installing an original Flat slide carbs react poorly if there isn't enough "draw" in the airbox. A GSXR suzuki with the airbox lid removed will not come off idle it will just backfire from the lean condition created.)
My bike didn't have a cover over the air cleaner at all when I got it,I suppose I thought they all came that way.But after reading his post I researched the innerweb and found out different, they did in stock mode use those covers ,so I copied the design of an original cover for a 900ss ,took me all of 10 minutes to make.The bike runs flawlessly right through the rpm range.It's scary fast,no hick ups anywhere.Blows right up to red line with no problem.(To be honest I have lost some of that wonderful low end grunt,It gets there, but not as quickly as before.(probably needs a little more air, ha ha )I know I can live with that trade off.Man was that a bugger to figure out,I knew there wasn't a fuel delivery problem,and the carbs were squeaky clean,the ignition system checked out fine,I had the carbs adjusted and balanced to perfection,they were in specs as far as jetting and all,I just couldn't figure it out,but now its all good.
I do have a couple questions though ,
1) someone who knows, needs to explain how this is possible,shrinking down the intake volume of air can help an engine run better?
2)does anyone have a Ducati 900 air box cover with snorkels ,that is unmolested they will sell me ,I doubt my card board version will hold up for very long.
What a great resources this forum is.Thanks again Randy
(https://i.ibb.co/jH20Kp9/20190702-164236.jpg) (https://ibb.co/jH20Kp9)
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(https://i.ibb.co/VBqz2yP/3908300926-8aa9fa0ddb.jpg) (https://ibb.co/VBqz2yP)
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Congrats on solving the problem. WG is the best!
Maybe this will work.........https://www.ebay.com/itm/Ducati-750ss-900ss-Airbox/322561888159?hash=item4b1a2fcf9f:g:xOUAAOSwnK9ZScf5 (https://www.ebay.com/itm/Ducati-750ss-900ss-Airbox/322561888159?hash=item4b1a2fcf9f:g:xOUAAOSwnK9ZScf5)
Paul B :boozing:
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Glad you got it fixed. And I love your home brew air filter cover. Guzzi content !
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This is interesting , my bike and the OP's bike with the same engine I believe,mine has the V2 stamped heads .His needs the stock airbox to get it running sharp...My runs sharp with no air box.. Something to think about...
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Randy, at the time the instructions I remember from Factory Pro were to remove the snorkels only from the lid of the box with the K&N. But I recall others having the lid removal set up without having issues. Its worth a try, but I doubt that taping a portion off will make a difference.
In my experience jetting another ‘97 SS-CR, identical to this one, removing the snorkels has a noticeable leaning effect and removing the airbox lid has a big jetting effect. If the bike isn’t jetted to suit, it won’t run well.
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It’s too bad that there is not a Ducati website that is comparable to WildGuzzi. I’ve looked but haven’t found one.
Which is a backhanded way of saying how wonderful this forum is.
Really? Ducati.MS not a good forum IYO?
There's a ton of technical threads there and a good number of really tech savvy contributors covering all types of issues for all types of Ducatis.
I'm surprised you have that opinion of Ducati web sites and don't know how you could have reached it quite frankly. :undecided:
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I don't know where that is coming from,I never once said anything bad about any Ducati site..This Ducati 900ss is new to me and I know of a couple guys in the Wild goose club that own them,That's the reason I'm asking Guzzi guys about Ducati's ,they are fluent in Italian.
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wow
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Hallelujah It's fixed!!!just got back from a 40 mile ride ,2 lane ,twisties and interstate,Wow! what a difference,it runs beautiful. Thankyou,Thankyou To one and all, who helped me figure this crazy problem out .
Today mcmuck provided the final piece to this puzzle I needed, with his posting,here is part of it; Posted by: mcmuck
« on: Today at 08:53:31 AM » Insert Quote
(Hi There! try removing the K&N filter and installing an original Flat slide carbs react poorly if there isn't enough "draw" in the airbox. A GSXR suzuki with the airbox lid removed will not come off idle it will just backfire from the lean condition created.)
My bike didn't have a cover over the air cleaner at all when I got it,I suppose I assumed they all came like that.But after reading his post I researched the innerweb and found out different they did make those covers so I copied the design off an original cover for a 900ss ,took me all of 10 minutes to make.The bike runs flawlessly right through the rpm range.It's scary fast,no hick ups anywhere.Blows right up to red line with no problem.(To be honest I have lost some of that wonderful low end grunt,It gets there, but not as quickly.(probably needs a little more air, ha ha )I know I can live with that trade off.Man was that a bugger to figure out,I knew there wasn't a fuel delivery problem,and the carbs were squeaky clean,the ignition system checked out fine,I had the carbs adjusted and balanced to perfection,they were in specs as far as jetting and all,I just couldn't figure it out,but now its all good.
I do have a couple questions though ,
1) someone who knows, needs to explain how this is possible,shrinking down the intake volume of air can help an engine run better?
2)does anyone have a Ducati 900 air box cover with snorkels ,that is unmolested they will sell me ,I doubt my card board version will hold up for very long.
What a great resources this forum is.Thanks again Randy
(https://i.ibb.co/jH20Kp9/20190702-164236.jpg) (https://ibb.co/jH20Kp9)
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(https://i.ibb.co/VBqz2yP/3908300926-8aa9fa0ddb.jpg) (https://ibb.co/VBqz2yP)
So I see that you have stock mufflers, but one route you could take is to go with the Dynojet Stage 2 jet kit 7201 for $120. This kit is intended to be used with the open air box. But then you would need to get proper mufflers so you can hear this beast sing...which is mandatory in my opinion...
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An airbox is effectively a slightly pressurized chamber that provides stable and consistent airflow to the carbs . Modern motorbikes are tuned to run with the airbox in place , what you have done is put it back to factory spec .
I might need more caffeine , hopefully this makes some sense Randy :huh:
Dusty
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What you basically did was enriched the a/f mixture. Same as when you applied the choke.
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I would look to getting bigger jets and a exhaust to unleash more power. I have had 4 ducati's, including a 2 valve air cooled bike with carbs and all have had either Ducati Performance open airbox lid that came with the full termi system or a aftermarket jet kit and instructions to drill a bunch of holes in the factory airbox lid. All ran great - no issues revving out.
looks like this but not carbon -
(https://www.bellissimoto.com/image/cache/catalog/C4US/S4R/Airbox/open-carbon-filter-cover-800x800.jpg)
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Randy.....fiberglas s your cardboard lid and spray paint it black. Glass matting, resin & activator w/black paint has to be less than the used Ebay one. Guzzi content.
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Thanks, but I found one ,a nice guy Ed Milich from Guzzitech,on ebay $45.00 including shipping from California .Can't beat that with a stick... :thumb:
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True. :thumb:
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Ed could probably provide you with jetting specs for open airbox / pod filters.
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Ed could probably provide you with jetting specs for open airbox / pod filters.
I listed the jetting , float levels and placement of the various vent hoses when using pods on a 900 ..But not all 900's are the same ..For the Monster ,96 was the last year of the big valve, hotter cam V2 heads..I'm not sure if the 900 SS continued with the V2 stuff...???
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Thanks, but I found one ,a guy Ed Multch Milich from Guzzitech,on ebay $45.00 including shipping from California .Can't beat that with a stick... :thumb:
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I had no idea the post '96 motors were lesser spec.
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I listed the jetting , float levels and placement of the various vent hoses when using pods on a 900 ..But not all 900's are the same ..For the Monster ,96 was the last year of the big valve, hotter cam V2 heads..I'm not sure if the 900 SS continued with the V2 stuff...???
All carb 900SSs are in the same state of tune, with sport oriented heads/valves/cams.
As noted later Monsters and also Cagiva Gran Canyons had 750 heads/valves/cams on 900 cc cylinders. This reduces power by perhaps 5 HP, about 68 stock versus 73 or so for an SS. Not a factor for a ‘97 900SS CR.
Removing the air box lid on 2V Ducatis of this era potentially adds power due to more air flow at a given throttle position, the dynamically active part of the air box is below the filter so air box tuning issues do not result when removing the lid. The factory lid reduces intake noise and makes sure the filter stays dry, but reduces power. When it is removed the increased air flow needs more fuel or a less combustible mixture occurs, lean misfire etc, which does not allow the added power to occur. Therefore unless the carbs are jetted for the displacement, heads and air box configuration the bike runs poorly.