Triumphrat

Mark62

I recently resync my carbs at idle. I noticed that when I increased the throttle the sync was gone. So what I did was sync the carbs at 3500 rpm (crank up the idle knob). Yes at idle they are out of sync, but at cruising rpm they are now even. Today I went on a test ride and what a HUGE difference this has made. I now have very little vibration at interstate speeds!!! Overall the bike is less "buzzy". I wish I had done this 20k miles ago.
I asked a pro motorcycle mech about this and he said it made sense. He also had never done a sync on a bike with 50k miles on it.
The gauge I have is one of the mecury filled types.
Mark

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We can put a man on the moon, but concrete and asphalt cannot be made to meet evenly.

93-Daytona

Hi Mark glad to hear your bike is running much better. Yes it does make sense to check the sync further up the range. However, if the sync is out at idle it suggests a number of things to consider. Setting syncronization higher up the rpm range is masking the core problem.
I suspect you have either low compression in one or more cylinders due to a valve leak or worn set of rings.
A cylinder leak down test will pin point any problem.
This is done by removing the tank and spark plugs.
Each cylinder in turn is put at DTC on the compression stroke. A special adaptor is screwed in then the gauge applied with 70psi from a filtered compressed air line fitted with a water trap. The engine MUST be cold.
By reading the guage and listening with a tube to the inlet manifold,exhaust manifold and engine breather you can evaluate the amount of leak from each area. Ideally you should have between 6 and 15% leakage on each cylinder. Putting the tube into the adjacent plug hole will also test whether there is a leak from cylinder to cylinder. Removing the header cap will show up any head gasket leaks. Pretty conclusive test.
The reason your trophy runs well when syncronized at 3500rpm is because the combustion process is quicker and not allowing the guages to detect the lack of even compression over the cylinders.
You may also find you may have got the engine too hot during setting initially which will also throw things out.
The other thing to check is the pilot mixture. Any difference in idle mixture will have a small effect on the vacuum reading. I do an initial vac set then adjust the mixtures with colortune plugs, then a final vac set when tuning. I then leave the synronizer connected and do a road test noting the coloums. A idle recheck is done on return as the engine is now at normal running temp. I use Morgan carb synronizer. Has SS rods in bronze bushings rather than mercury.
Worth a check
Cheers Kerry

Mark62

Thanks Kerry,
I know I am overdue for a valve adjustment, so that is probally the problem. I do not have the tester for any kind of exhaust anylizing, so checking the pilot settings will have to be done by the pros. When I advance the throttle past 2000 rpm the mecury evens out and rises at the same rates. I put 150 miles on the bike this past weekend and the comfort level increased considerably. My right hand would go numb after 20 miles at interstate speeds. I still have vibs there, but not as bad.
The pro mech that I talked agreed with my theory of why sync at idle, I don't ride at idle, sync at a higher RPM....
Mark

__________________
We can put a man on the moon, but concrete and asphalt cannot be made to meet evenly.