WR400 tried YZ timing...didn't work!?

4 replies to this topic
  • pdrides

Posted May 22, 2008 - 06:01 AM


I posted a while ago asking for advise on getting a little more snap on my '99 WR400. A suggestion was made to change to the yz timing. Made sense to me. My mechanical skills must suck because I couldnt even get the bike to start after moving the exhaust cam 1 tooth clockwise. I double checked to make sure I did everything according to instruction. I finally gave up changed back to the WR cam position and she started right up:banghead:

The grey wire,throttle stop mods have been done, the bike has been running great with the exception of some random stalling from 0 to 1/8 throttle(I'm going to address that as soon as I resolve this mystery). The plug looks great,nice light tan in color. From what I've read here the jetting looks typical, 170 main,45 pilot,60 starter,200 main air,75 pilot air, 90 slow air. Fuel screw is out 2 turns. I live in Massachusetts so I'm pretty close to sea level and the weather has been between 55 and 70. I recently cleaned the carb (soaked it over night, blew it out) so I pretty sure there aren't any clogging issues although of course there could be.

Two things I notced that seem wrong. I can't get the timing mark on the intake to line up exactly even w/ the top of the cylinder, its either a little high or low. I've tried it in both positions and it will only work slightly high. I'm wondering if the sprocket has possbly moved on the shaft or the chain might be stretched a little.
The other thing is I 'm getting a puff of blue smoke after warm up. It only happens once after the bike sits over night...rings?

I realize this bike is nearly 10 yrs old and without completely rebuilding it I may be getting as much as I'm going to out of it. I don't know that I would have the skills or time for that. Any suggestions would be greatly appreciated.
I apoligize for the new thread, I searched and did'nt see anything that really covered my problem.Thanks in advance...

  • SXP

Posted May 22, 2008 - 09:27 AM


The other thing is I 'm getting a puff of blue smoke after warm up. It only happens once after the bike sits over night...rings?

Or valve seals.

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  • pdrides

Posted May 24, 2008 - 05:14 AM


Valve seals, ok is there a simple way for me to test them?

  • Frostbite

Posted May 24, 2008 - 10:14 AM


Valve seals, ok is there a simple way for me to test them?

If the engine puffs for a minute after sitting it's most likely seals and/or valve guides.

Worn rings generally smoke while you're driving and on the gas. Smoking at initial startup and during decelleration is a sign of bad seals or guides.

A simple test is to run you RPM up in 3rd or 4th gear, then chop the throttle and let the engine decellerate for a 10 seconds, and then give it a shot of gas. If the seals are bad, the engine will suck oil past them during the decelleration, and then burn it off suddenly when you crack the throttle. If you see a puff of blue when you crack the throttle after decelleration that's a sign of bad seals or guides.

Personally, I wouldn't worry too much about bad seals, unless you're really going through oil, or you're smoking badly and it's embarrasing. A little extra oil isn't going to hurt anything. I'd wait until something else warranted a top end teardown and then replace the seals.

  • pdrides

Posted May 24, 2008 - 02:50 PM


Sounds good to me:thumbsup: I'd rather be ridin' than wrenchin'. If it doesn't get worse than I'll probably wait till the next valve adjustment. :thumbsup: Thanks


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