Jump to content
Sign in to follow this  

Carbon Fouling help

Recommended Posts

Hi guys, quick question, my bike 1999 wr 400 runs great with new plug but after a full day of riding it wont start or starts and instantly dies, if i put a clean plug in it fires up first kick, could this have anything to do with my valve clearances? if not im guessing fuel mixture problem, if fuel mixture what screws do i adjust to where?

Share this post


Link to post
Share on other sites

thought it would be that, although it ran fine for months at a time and then all of a sudden it stuffs up after every ride, when its riding it runs great never bogs nor backfires.

  • Like 1

Share this post


Link to post
Share on other sites

Jetting does not change over time, so it can't be jetting.

Besides, jetting that rich would make it run terribly. 

 

More likely you have worn out valve guides, rings, etc and you are passing oil.

 

Time for a rebuild.

Share this post


Link to post
Share on other sites

I am sure it needs a rebuild but I didn't think tht affected the plug,while I'm on the topic can anyone tell me what can go bad I I kept riding the bike?

 

If your valve guides are worn, most likely your cam chain, and cam tensioner are worn out too.

If that is the case, you will own a large paper weight if you do not follow the standard service in the service manual.

Valve guide wear is usually a sign of really bad air filter maintenance, extremely lean jetting,  or tons of hours on the motor.

Share this post


Link to post
Share on other sites

Okay I'm on about half that,could a bit of shit in a air intake cause "rich" jetting which lead to carbon fouling?

No.

Do a leak down test or tear it apart.

 

You are saying that your '99 motor has less than 300 hours?

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

Reply with:

Sign in to follow this  

×