Quote:
Originally Posted by Craig380
I think that's a wise approach. On SVs, the clearances will close up with age & miles, rather than get wider, so they are unlikely to become noisy. But I agree that given the age & mileage, looking too deeply isn't really worth it. 150psi compression is 10.3:1, which is good (especially if the engine was cold at the time of the reading, 'cos the reading will be even better when at working temperature).
On the fast idle check, if it already starts from stone cold on the first press of the button, and immediately idles at around 2,000 to 2,200rpm (depending on the ambient temp - higher ambient temp = lower fast idle), then settles down to about 1750rpm after a few seconds, the fast idle is absolutely fine. Don't waste your time following the manual and reading voltages etc, just go by the rev-counter and how the engine behaves.
The TB sync IS worth doing. I used to do mine visually - lift tank, remove airbox lid & filter, and manually turn the cog on the STV motor to open the STVs. Then look closely at the main butterflies and make sure they both start moving at the same time as you gently open the throttle. If you have vac gauges or use the 'long U-tube' method, of course that's more accurate.
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That is really helpful.
I’m pretty confident the valve gear is okay, and given the good (and equal) compression on both cylinders I don’t think it is worth risking a mechanical calamity with such a high mileage engine. I checked the compression with the engine stone cold (whilst changing the radiator), so I’m quite pleased with the CR.
The cold tick over is not quite as you describe it on my K6 - it starts straight away from cold, then ticks over at the lower part of the range (1200 RPM), as the engine warms up it gradually goes up to 1400 RPM. I didn’t even realise the engine had a fast idle mechanism until I found it in the workshop manual (whilst looking for the TB balance procedure) last week, so it’s behaviour on start up didn’t cause me any concern. It looks like the fast idle is not doing quite as it should though, and it appears to be a simple voltage check and adjustment to sort it, so I think that is something worth doing.
I see your point about checking that the throttles are coordinated visually, I think that would work pretty well. As I’m going to have to strip the bike a bit anyway to have a look at the fast idle setup I might as well use the vacuum gauge I can borrow from a mate and balance the throttles at the same time. It looks like a pretty straightforward procedure.
Many thanks for the advice - you have understood exactly what I’m trying to achieve with this project.
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