How important is valve clearance on a crf250r?

Question

i sealed up my crankcase with jb weld, awesome seeling compound. i still cant get power out of my bike at full open throttle, it starts normally, runs ok until i open the throttle fully then its like something is holding it back. the carb has been taken apart looks fine. recently has been putting tar like deposits on the plug. a mechanic told me once the valve clearance is out its time to do a top end rebuild or the piston skirt is going to give and the top end will go.

Answer 1

shim those valves to nore more tha .006 and that should do it

You may need to order a new power band

try indysuperbikes.com they have the best deals

Just ask Wiggysan he'll tell you

Answer 2

Valve clearance is very important,try running an engine without it.

Answer 3

How important ?

Very pal. Do you know how hard a single valve has to work?