V1000 Timing Trouble - Missing flywheel marks

[mneumann]

Sounds like that RH carb is running lean.  When was the last time you cleared the jets?  Some of that real fine grit that is in the carbs (white stuff) could be starting to plug the main jet on that side carb.  One thing you can do is check the air flow through the carb mouth with a 1/4 " fuel line while the bike is idling. (after reaching op. temp.)  Don't stick the tube in your ear but place it to the outside of your ear.   

Just rejetted and cleaned the carbs. That’s a good idea with listening though. I’d think carbs as well but the fact that the left is fine (maybe slightly rich) makes me think timing.

[mneumann]

The 2 and 3 deg static can be set with the bike at idle with a light. Or you can use a multimeter hooked to the point and ground and watch for the point to open.

Tom

It has dyna ignition. But I did use a 12v light to set it. The problem was I didn’t have an exact point to set to. I just ball parked where it should be based on what I’ve seen online of the markings. That way I could at least get the bike on and go from there. I’m liking the idea of a timing light with the advance. I’ll be near harbor freight this weekend and pick one up.

[Tom]

Consider that the fine tuning of your bike is of 2 separate single cylinder engines that need to be synchronized together.  Definitely check your carbs for flow. 

[n3303j]

Why not use a Piston Stop and Degree Wheel to find exact Compression TDC for one cylinder?

Then use the Shop Manual and the Degree Wheel to to determine and mark all the timing locations on the flywheel.

That way you have standard reference marks forever.

[Tom H]

You say you re-jetted. What did you re-jet to?? What carbs? What slide?

For everyone here...... Can a Dyna ignition system timing be off on one side? Sorry, I don't know Dyna.

Tom

[mneumann]

Why not use a Piston Stop and Degree Wheel to find exact Compression TDC for one cylinder?

Then use the Shop Manual and the Degree Wheel to to determine and mark all the timing locations on the flywheel.

That way you have standard reference marks forever.

I was thinking I will do this as well. Now is there a benefit to a piston stop vs placing a straw and visually seeing where TDC is? Maybe that’s a dumb question but I have seen both mentioned.

[mneumann]

You say you re-jetted. What did you re-jet to?? What carbs? What slide?

For everyone here...... Can a Dyna ignition system timing be off on one side? Sorry, I don't know Dyna.

Tom

Rejetted to 140 main and 55 pilot. Needle on second notch. It seems to have great throttle response, idle and cold start.

[n3303j]

I was thinking I will do this as well. Now is there a benefit to a piston stop vs placing a straw and visually seeing where TDC is? Maybe that’s a dumb question but I have seen both mentioned.

Piston Stop handled with proper care is more accurate than a straw.

[pehayes]

Now is there a benefit to a piston stop vs placing a straw and visually seeing where TDC is? Maybe that’s a dumb question but I have seen both mentioned.

No dumb questions.  The straw is a coarse instrument.  The piston stop is precise IF you know how to use it.  The straw lets you sort of 'feel' where top dead center is located, plus or minus a few degrees.

Set up a degree wheel and the piston stop.
Gently roll the engine until the piston rises and  hits the stop.  It won't go any further.  Mark that point on the degree wheel.
Now gently roll the engine in the opposite direction of rotation. The piston will drop to bottom and then rise again until it again hits the stop and goes no further.  Mark that point on the degree wheel.
Look at your two marks on the degree wheel.
Top Dead Center is precisely midway between those two stop marks.

Patrick  Hayes
Fremont CA

[n3303j]

....and I can't overstress "GENTLY" touch the stop in both directions. Then repeat to be sure you didn't knock some carbon loose mid procedure and get a false reading. If both checks match then you probably have a good reference.

Piston stop has a ball end and too aggressive rotation could dent the piston crown decreasing procedure accuracy.

[Tom H]

Thank you Patrick. I had been wondering about the piston stop. Also been wondering about TDC while using a straw. How many degrees can the crank rotate while the straw or a dial indicator will not move??

This does not matter that much for valve adjustments, but for timing at 2 degrees, it could be significant??

Tom

[pehayes]

I fabricated a piston stop set you can borrow (if I can find it).  Hole through allows escape of compressed air.



Patrick Hayes
Fremont CA

[Tom H]

If anyone is interested. At least on my Ambo 750 and probably all round fin engines, the TDC marks on the block are 25 ring gear teeth apart.

Tom

[wirespokes]

Tom - 25 teeth apart doesn't sound right to me.

With 96 teeth on the ring gear, it should be 24 teeth between TDCs since it's a 90 degree V.

Is there something I'm missing?

Do all the tontis have 96 teeth ring gears?

[Tom H]

I put a ring gear on my Ambo flywheel. I lined up the arrow on the flywheel with the pointer on the block for #2 cylinder. A ring gear tooth lined up with the arrow and the pointer.

I counted the tooth that was lined up as #1, then counted the teeth until I got to the next pointer and called that tooth #25.

I guess that you could also say that there were 23 teeth BETWEEN the pointers.

AFAIK, an per MG Cycle, I had the standard ring gear that would fit my Ambo, Eldo and V1000 (not sure what bike, G5 maybe).
http://www.mgcycle.com/index.php?main_page=product_info&cPath=193&products_id=2460

Edit: I checked my ring gear and flywheel. There are 25 teeth as long as you include the ones at the marks like I stated. I also decided to put a TDC mark for #1 cylinder on my Ambo V1000. I also verified that a mark I put on the timing gear cover for #1 was correct. I made the mark while the engine was on my work bench.

I lined up #2 on TDC on my belt pulley, then turned it to the #1 TDC mark I made using the bolt on the nose of the crank. Then I put a mark on the flywheel, center of the timing hole on the bell housing. Then I turned the ring gear one tooth at a time with a screwdriver. I was expecting 25 teeth, I only made it 23 pulls of the screwdriver before it lined up. As I mentioned before, there are 23 teeth between the marks, I think that is why I only made 23 pulls.

Tom

[mneumann]

Thank you all for the information! I found a section in Guzziology that listed the G5 specs. TDC to Static is 4mm (~2deg), Static to full advance 62mm (~31deg), and S Full advance to D TDC is 114mm (~57deg). I'm going to go with these unless I hear differently. It has seemed a little confusing on the wording of which way to rotate the engine between different manuals, however my take away has been that the new marks belong above the D or S if you are looking into the window at the flywheel.

[wirespokes]

Tom said "I counted the tooth that was lined up as #1, then counted the teeth until I got to the next pointer and called that tooth #25."

I think that's the difference. I wouldn't count the first one. It's like saying the starting line is one foot, when a foot long isn't till a foot later. LOL

We're talking about a unit of distance here. If there's a tooth at the starting line, that doesn't mean there's already a distance of one tooth. A tooth is 7.5mm - look at it that way.

I guess the way you did it can communicate - but make sure the other guy knows the parameters. It's not actually the distance of 25 teeth, it's in the way it's counted.
 
mneumann - yes, you've got it. The engine rotates clockwise looking at it from the front. The full advance and static marks are above the TDC mark.

[Tom H]

I should have posted a picture to show what I was trying to say. Sorry for the confusion

Tom

[chuck peterson]

No dumb questions.  The straw is a coarse instrument.  The piston stop is precise IF you know how to use it.  The straw lets you sort of 'feel' where top dead center is located, plus or minus a few degrees.

Set up a degree wheel and the piston stop.
Gently roll the engine until the piston rises and  hits the stop.  It won't go any further.  Mark that point on the degree wheel.
Now gently roll the engine in the opposite direction of rotation. The piston will drop to bottom and then rise again until it again hits the stop and goes no further.  Mark that point on the degree wheel.
Look at your two marks on the degree wheel.
Top Dead Center is precisely midway between those two stop marks.

Oh that's good stuff...so to be clear..

The piston stop doesn't need to be at TDC? You set the stop, close, but no need to exactly hit TDC. Or anywhere. Could be an inch before TDC. You roll backwards 180 degrees through a cycle, and boom! Split the difference is TDC?

I've got six, oops, now seven mopeds that need that....



Patrick  Hayes
Fremont CA

[wirespokes]

Chuck - the reason for using the piston stop is because the piston moves very little for quite a while at the top of the stroke. It's better if the piston-stop is close to TDC, but works as long as it's not inches away. Besides, the piston stop is only so long anyway.

I've never really needed a piston stop, but it's looking more and more like I'll be making one. I'll probably put a hard rubber insert on the end.

[dxhall]

In place of a piston stop, some guys with too much time on their hands have made a TDC gauge.  Like this one for a Centauro:




private image hosting


Because of the “dwell” at TDC, though, you still need the degree wheel.  You use the tool to find the dwell position, and set the dial to zero.  Then you turn the motor in one direction to drop the piston, say .020, then turn the motor the other direction back through the dwell position to .020 again, noting both of the .020 measurements on the degree wheel.  TDC is then read on the degree wheel half way between the two .020 measurements. 

More accurate than a piston stop?  Maybe. Make any difference on a street motor?  I doubt it.

[Chuck in Indiana]

I have a dial indicator setup. Is it more accurate than a piston stop and degree wheel? Not really. It is certainly easier, though, when you are dealing with cam timing.

[n3303j]

I get concerned that the indicator slide is being pushed from the diagonal rather than along its axis. This is not how those long travel indicators were meant to be actuated. That push direction is sliding the indicating shaft across the top of a debris covered piston. Indicator is fine if head is off and indicating rod is parallel to the bore resting on a single portion of the piston. Otherwise I would be suspect of TDC readings made at an angle through the plug hole.

Piston stop just touches one spot on the piston. It is the identical spot in either rotation.

Don't make the tip out of hard rubber. Use steel. Rubber will deform and impair accuracy. A spherical end handled with a reasonable amount of care will not damage your piston.

[dxhall]

That’s not the purpose of the indicator.  Since the spark plug hole is offset and angled in relation to the piston’s direction of travel, an indicator screwed into the spark plug hole will not show the actual distance the piston travels — that is, if the indicator shows .020, that doesn’t mean the piston actually moved .020 down the bore.  The purpose of the indicator is just to give comparative measurements for the degree wheel.

[n3303j]

That’s not the purpose of the indicator.  Since the spark plug hole is offset and angled in relation to the piston’s direction of travel, an indicator screwed into the spark plug hole will not show the actual distance the piston travels — that is, if the indicator shows .020, that doesn’t mean the piston actually moved .020 down the bore.  The purpose of the indicator is just to give comparative measurements for the degree wheel.

Never said purpose was to derive exact measurements. The object is to detect when piston travel reverses.

I'm just saying that it is poor technique to actuate a long travel indicator by applying a pressure load that is not parallel to the axis the indicating rod moves. Namely, push the rod straight in. That's how it was designed to work.