Join Date: Aug 2008
Location: London, , England
Here's a New Year teaser for everyone. My 900 bevel has had a problem for the last six months; it goes like this:
The bike starts instantly on the button, I warm it up for five minutes and ride away, engine running perfectly, then about half a mile down the road one cylinder misfires and cuts out. I carry on and the cylinder chimes in and out until by another half mile it has cleared, to give no more problems. Until today. This time it did not chime in again and I was forced to complete a circuit on one cylinder until I could get it back home. Bummer.
I've not bothered to try to find the problem before now, because once it starts running ok again I forget all about the misfire. When I got home today I found that it was the rear cylinder that was not running, so I took out the plug, which was soaking wet, and checked for a spark, and boy was there a spark! So no problem there. After fitting a new plug to the offending cylinder, she fired right up, but I didn't feel like taking her out for a test run.
I use iridium plugs and I'm wondering if they are more susceptible to fouling at low temperatures? I'm also wondering if the engine is oil fouling the plugs on start up, although if I check the plugs after a run, they are a lovely clean, dry tan colour, as are the piston crowns, and the engine does not use any oil at all. But, as the engine is 33 years old and has never been touched, the valve guide seals may be a little brittle and hard by now! Maybe it's time for a grade hotter (running) plug.