HEADS UP!!!

Site upgrade in progress... Core site functions are working, but some non-critical features/functions will be temporarily unavailable while we work to restore them over the next couple of weeks.

Please post any bugs you encounter, but before you do, check to see if it's already listed.

Thanks for your patience while we work to improve the community.

Sign in to follow this  
Followers 0
kirk_12

Shems 426

13 posts in this topic

Do You mean the valve shims? If so then yes because the valves wont open very far.
If the valve clearance was .20mm too loose, the engine would be ridiculously noisy, but there would not be enough change in lift to notice even a small drop in power. The answer to the question is no.

Kirk, why do you ask?

Share this post


Link to post
Share on other sites

i went ridin sunday an my bike bogged down a couple of times which has never happend, then on my way home i got out ran by a crf 250 that i have beat like 10 times!!! jus felt like i was losin power

Share this post


Link to post
Share on other sites

last monday ... but i didnt ride any that week cuz i was in louisville the whole week ...

Share this post


Link to post
Share on other sites

Do you have any ticking in the engine, more then normal i should say. Pull your plug out and check the color, black and wet is a sign of flooding could be carb troubles, grey or nothing on the plug is ok, white running lean possible air leak in the intake or other carb issues.

Share this post


Link to post
Share on other sites

actually it did start ticking like the shems are loose, i know on 426s that when the valves wear they loosen as to hondas tighten ... but i will check the plug an for air leaks ... then if all is good i will get my uncle to shems it!

thanks guys.

Share this post


Link to post
Share on other sites
actually it did start ticking like the shems are loose, i know on 426s that when the valves wear they loosen as to hondas tighten ... but i will check the plug an for air leaks ... then if all is good i will get my uncle to shems it!

thanks guys.

The yamahas do just like the hondas do and tighten as they wear out. The seat surface gets worn down and causes the valve to drop further into the seat which causes the SHIMS to tighten. How many hours would you say are on the engine? Because you should have absolutely no trouble beating a crf250r in a straight up drag race.

Share this post


Link to post
Share on other sites
actually it did start ticking like the shems are loose, i know on 426s that when the valves wear they loosen
Wrong. Normally, the wear occurs only at the valve face and seat, which causes the valve to move up into the head, reducing clearance.

Share this post


Link to post
Share on other sites

well i guess the local yamaha shop is wrong if they tighten wen wore cuz they told me they loosend wen wore .. but anyway i checkd the clearence jus now and the intake was very loose an the exhaust wasnt that bad but still loose

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0