Tuesday, May 12, 2009

Idles wild, dies while idling

I got it all back together with the Wiseco 9:1 piston a few days back. I heat cycled the new piston and broke it in 'nice-and-easy'. Here's the very first kick after reassembly:

I was still having the problem of stalling seemingly at random. A terible thing to happen on a kickstart-only bike in the middle of traffic. Especially one that is higher now and therefore harder to kick.

My mind jumped to a list of conclusions, such as, "it's that rust sediment I keep seeing in the carb bowls that's making it die". I went out on a wild goose chase for a paper filter that's going to fit in my small space. After finding mostly too large automotive paper filters and finally being told that paper filters are inferior to the little pressed-brass-pebble ones anyway, I bought a much-needed piece of fuel line at the last stop. I'm not sure if I believe him about the filter comparison, but I had never cleaned the petcock so I figured I had better take it out and clean that pre-screen off. I forgot to drain the tank on the reserve setting. When I went to remove the petcock, I found out first hand how much gas is in the reserve setting (quite a bit) and enjoyed the fringe benefit of the left side of my engine being degreased. Never did clear up that idle mystery though.

Today, I had decided to undo my stator's ground wire from the intake manifold bolt, to make sure it wasn't interfering with my tightening of the manifold. Stock stators don't have these ground wires, it's an add on by Ricky Stator, so you just sort of bolt it on wherever you can. I was tired of bolting it onto the sort of high-torque rocker box bolts. It was smashing the hell out of the poor little ring terminal. So I just put a wire extension with a gator clip on one end and clipped it to the frame until I feel like doing some electrical tailoring.

Finally, I got around to testing for leaks around the intake with an unlit propane torch with no results. The stator ground was still floating loose at this point and I thought I saw a spark. It worried me a little in the sense that sparks like that made a disaster possible, but how hard it was to light that torch with an open flame put my worries at ease. No leak detected from propane probing.

I checked the valve clearances and sure enough, they were the culprit. My exhaust and intake were both too tight, almost as if I'd gapped the two on that side as if they were both intakes and the two on the other side as exhausts. Wierd. Anyway, it idles without dying right when the light turns green, so that's good. I had forgotten how rock-solid at idle these engines are with all my chokepulling nonsense to deal with this issue. Now it would be nice if I could be flying along at 70mph and then pull in the clutch and know the engine would still be idling faithfully, but I don't think it's that good. I'm definitely on to something though.


1 comment:

  1. just don't pull in the clutch at 70, you'll be fine!

    i've read around about these things being sensitive to valve gap at idle. glad you found the issue.