Wildguzzi.com
General Category => General Discussion => Topic started by: Guzzigary777 on May 21, 2015, 12:36:11 AM
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The old air box on my 1000sp (1983) was getting to be in pretty sad shape and was always a pain to work around, so I recently went to k&n pods on the stock 30mm carbs. Jetting was 125 main/ 50 pilots I've gone to 128's and shimmed the needle with a small flat washer, but while running much better overall, it seems to flatten out on top end and when stopping after prolonged high speed use, wants to die and refuse to start until I twist the throttle 4-5 times ( the acc. pumps squirting fuel each time ) before it will relight. I figured it needs more fuel (i.e. bigger main jets), but a friend is telling me I need to readjust the float levels. Any Thoughts?
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Have you tried just leaving it as it was and then doing a series of chops to see what, if anything, needs changing. The V series needles are very coarse. I always found they were best left alone.
Pete
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Checking the float levels might be a good idea, but if it starts running out of fuel on top end check your fuel flow through the petcocks.
You might need to borrow a clear float bowl to determine if the engine is using more fuel than the system can supply to the bowls.
Also check the tank vent.
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My Cal III wouldn't run at WFO when I bought it. Had 130 mains. Went to 142s (as in the T and SPII) and it runs well.
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On my 850T3 Cali, when I swapped over to pod-filters I upped the mains from 120 to 130.
Proved to be too much, with very black plugs so have dropped back to 120s for the moment, which is better, with no apparent issues but plan to try out 125s when I get new needles as one of mine has a noticeable ridge.
One thing at a time though. ;D
cheers
eib
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+1 on Pete's comment. K&N etc doesn't require a jetting change from stock. Failure to pull on top is likely from overly rich jetting.
Not all carb issues are from"EPA lean" issues. I don't know if I've seen it on a Guzzi.
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Make sure the filter length is at least 2 times the diameter or it won't run well at WOT. I have drilled out petcocks and banjo's internal passages to get rid of the stumbling after a high speed blast. Don't know if it helped or not but it was fun to do. If the engine dies when the throttle is quickly closed, it's a sign of too rich, I think in the idle circuit.
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Make sure to leave the throttle intake throats in place to help the flow.
I went the route on my V7 Sport running without the intake throats ran like xxxxx to much of a sharp transition without the throats
TOMB
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The 85 1000 Cali 2 I built into a cafe type run at the Ohio standing start mile track did four runs between 116-117 MPH.. Stock engine, no mufflers on the stock head pipes, small K&N type air filters, 30mm carburetors with #132 main jets. Made no difference with air filters off or on.
As mentioned check you petcock flow...with the bottom plug removed from each carb measure the fuel flow...8 ounces in 30 seconds will support 35 HP per cylinder. The standard wide open throttle fuel use for gas engine is .5 pounds of fuel per HP per hour...Gas is 6.1 pounds per gallon and the actual flow rate measured needs to be doubled when measuring the flow at the carb bowl...Fade at high speed when jetting is acceptable is generally fuel flow...
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Do you have the line that connects one carb fuel line to the other?
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Do you have the line that connects one carb fuel line to the other?
The bike didn't have a crossover, one petcock to each carb.. I would say both petcocks should be open for heavy throttle use
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Make sure to leave the throttle intake throats in place to help the flow.
I went the route on my V7 Sport running without the intake throats ran like xxxxx to much of a sharp transition without the throats
TOMB
by this you mean v-stacks, and I agree...
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Have you tried just leaving it as it was and then doing a series of chops to see what, if anything, needs changing. The V series needles are very coarse. I always found they were best left alone.
Pete
Agree - do some chops - otherwise you're just guessing. If you havent changed the exhaust, you'll not need to mess with the jetting much.
And - before you do, Id recommend setting your timing dynamicaly at about 4k rpm. Balance the carbs at the same RPM, then set the idle and mixture. THEN - you're ready to do your chops. ...IMHO... :BEER:
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The bike didn't have a crossover, one petcock to each carb.. I would say both petcocks should be open for heavy throttle use
Hard to believe that two main jets could flow more fuel than a petcock can supply. If I take the fuel line off and open the petcock, it will empty the tank in about 4 minutes.
You couldn't run an SP out of gas in four minutes of any kind of running .....
Lannis
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Hard to believe that two main jets could flow more fuel than a petcock can supply. If I take the fuel line off and open the petcock, it will empty the tank in about 4 minutes.
You couldn't run an SP out of gas in four minutes of any kind of running .....
Lannis
This is more common that you think....Petcocks have fine screen that can become restricted...And you have to check fuel flow into the bowl to absolutely eliminate any suspicion... And for fuel to flow out, air need to flow into the tank...check the cap vent..loosen the cap as a test...
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This is more common that you think....Petcocks have fine screen that can become restricted...And you have to check fuel flow into the bowl to absolutely eliminate any suspicion... And for fuel to flow out, air need to flow into the tank...check the cap vent..loosen the cap as a test...
Did that while fettling the Norton. Emptied the tank by opening one petcock, and taking both Amal float bowl drains out. Gas had to come through the petcock, down the gas line, past the float needle, and through the bowl.
Gas was just splashing out, WAY faster than it could get through a main jet. I've often heard people say "You have to open both petcocks on such-and-such a bike or it will starve", but they are bound to be dealing with a clogged-up fuel system. As a get-home ploy, opening both petcocks may be necessary. As a regular thing, no way ....
Sometimes the same people that tell me that also "pump" their Amal ticklers while preparing to start the bike, like they would the primer bulb on an Echo chain saw. That tells me they've likely never had the float bowls off and seen what the tickler actually DOES .... :D
Lannis
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It's a bit more complicated that what you say. Amal concentrics standard needle jets flow just barely enough fuel to feed 30 HP per carburetor. Most of us racing that use Amals have the "two stroke" high flow bowls.
The complication is to function properly the carb float bowl needs to remain nearly full. When testing the float is down all the way, empty bowl .. But in reality the flow must be sufficient when the float needle and jet are maybe 20 percent open...
And just letting fuel spill out says what? Did you catch it in an measuring cup and time the flow for 30 seconds?
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It's a bit more complicated that what you say. Amal concentrics standard needle jets flow just barely enough fuel to feed 30 HP per carburetor. Most of us racing that use Amals have the "two stroke" high flow bowls.
The complication is to function properly the carb float bowl needs to remain nearly full. When testing the float is down all the way, empty bowl .. But in reality the flow must be sufficient when the float needle and jet are maybe 20 percent open...
And just letting fuel spill out says what? Did you catch it in an measuring cup and time the flow for 30 seconds?
'Ang on a mo ... If you're saying that the limiter is the 20% open (and I'm sure you measured that against 100%-open flow for 30 seconds to come up with 20% ;) ) float valve, then how is opening two petcocks going to help that? You could open 20 petcocks, and if the "almost full" carb bowl fuel level is holding the float almost closed, it's not going to help get gas into the jet ......
Wow, it IS complicated ....
Lannis
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'Ang on a mo ... If you're saying that the limiter is the 20% open (and I'm sure you measured that against 100%-open flow for 30 seconds to come up with 20% ;) ) float valve, then how is opening two petcocks going to help that? You could open 20 petcocks, and if the "almost full" carb bowl fuel level is holding the float almost closed, it's not going to help get gas into the jet ......
Wow, it IS complicated ....
Lannis
Yes complicated as in more than just petcocks ...The petcocks can be restricted by dirt/rust... The main jet may be restricted by a float system unable to maintain a proper fuel level. If the fuel levels falls off the jetting will go lean, the engine flattens outs. You're on BritBike so you know I'm there talking racing old Brit junk with other like mined guys...This topic is often discussed...In fact when I first built the LSR Triumph two years ago ,John Healy donated me two high flow Amal bowls knowing from experience the stock ones would be marginal ...I had to modify the 34MM Mikunis on it now for better flow....Yes, running wide open in high gear for 30 seconds is more severe than most street ridding but the theory is still the same. It has to be checked out if all else is normal and the problem persists....
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Found the problem guys. Thanks for all the suggestions. Normally I do all my own maintenance. but the last little trip I took, I had the bike serviced at a small shop somewhere in the middle of nowhere. Nothing much, just an oil and filter. It seemed like a nice little independent shop specializing in eurobikes. The guy suggested changing the plugs, since I had not changed them in about 20,000 MI. I said sure. Never thought any thing more about it. That was the last time I rode the goose before modifying the air cleaner situation. When I pulled the plugs to do jetting runs, I removed B9ES's. Screwing BP6ES plugs ( the proper plug) back in it made all the difference in the world.
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Maybe they were upsidedown?
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Found the problem guys. Thanks for all the suggestions. Normally I do all my own maintenance. but the last little trip I took, I had the bike serviced at a small shop somewhere in the middle of nowhere. Nothing much, just an oil and filter. It seemed like a nice little independent shop specializing in eurobikes. The guy suggested changing the plugs, since I had not changed them in about 20,000 MI. I said sure. Never thought any thing more about it. That was the last time I rode the goose before modifying the air cleaner situation. When I pulled the plugs to do jetting runs, I removed B9ES's. Screwing BP6ES plugs ( the proper plug) back in it made all the difference in the world.
I doubt the change from B9 to BP6 made that much difference. Given hotter one is projector and the other one isn't, they might even be equivalent. Like the old champion n9y (projector) was equal to the n4...