Adjusting valves wich way to lean?

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9/7/2017 5:22 AM

Working on a 2011 kx250f as of now bike is hard to start when cold. Intake valves are in spec, exhaust side has one below minimum clearance and one right at max. When I go to reshim is it better to aim for the min clearance or max clearance? I know right in the middle sounds like the safe answer but there has to be pros and cons to tight vs loose.


9/7/2017 6:08 AM

I always adjust mine in the middle. Valves will dig into the seat over time resulting in the clearance being tight. So if you want to go longer without an adjustment, put them towards the max clearance side. Obviously make sure theyre as close to the same as possible.

As far as any performance advantages... no clue.


2009 Kawasaki KX450F
2009 Kawasaki KX250F
2002 Suzuki GSXR 600

9/7/2017 10:06 AM

Unless you buy OEM shims you often have to err on one side or the other since they aftermarkets kits come in .05(?) increments. I have always gone a bit loose over tight with no issues......


9/9/2017 6:46 AM

I'd go with larger gap. As the valves sit deeper in the seat the gap will close and if the stems stretch the gap will close. So as long as you're within spec I don't see a problem.

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9/11/2017 6:06 AM

If there is a performance difference, I would say it would be tighter clearance with the advantage since any slack has to be taken up by the cam prior to valve lift beginning. If I'm picturing it right in my head (questionable, two sips into my coffee...) total lift is the same regardless, but duration would be shorter as the clearance increases, since slack would cause the cam to be further into the lobe before lift starts. I would also think it would seat earlier on the back side of the lobe as well.