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centaurus
18th January 2010, 10:26
I have crash-started quite a few bikes in my life but until last week, all of them have been thumpers (just coincidence).

Last week I was forced to crash-start my zx6r and I was totally surprised for two reasons:
- even a bit flooded it started almost instantaneously
- the engine didn't have almost any kick when engaging the clutch

I know the 4-inline engines are smoother, usually have a bit lower compresion than the thumpers and I also know this bike's clutch is much smoother when engaging/disengaging compared to any of the thumpers I've crash-started, but I didn't feel almost any kick at all when dropping the clutch.

Should I be worried about low compression or it is normal on this type of bikes.

As a background: the bike usually starts very well even when cold. Also, the bike doesn't smoke. It only puffs a little when really pushed.

Ixion
18th January 2010, 10:47
Reason is that crash starting, the compression resistance on a 600 is only that of a 150cc cylinder. You'd expect that bumping a 150cc would be easy. And a 600 is even easier, because you only have 150cc of resistance , but you have a 600cc flywheel weight to help bump it over.

R6_kid
18th January 2010, 11:07
At least you are on to it. I had a friends flat mate tell me that you needed to engage the starter (as in push the starter button) when you were crash starting a bike or it wouldn't start. I asked him what he would do if the battery were completely flat and his reply was that he'd be calling for a pickup... some people!

kwaka_crasher
18th January 2010, 11:14
Reason is that crash starting, the compression resistance on a 600 is only that of a 150cc cylinder. You'd expect that bumping a 150cc would be easy. And a 600 is even easier, because you only have 150cc of resistance , but you have a 600cc flywheel weight to help bump it over.

Add gearing differences between the high-reving 4-pot and the thumper and there is your answer...