My 1995 model was running great when I did a 200 km ride 3 weeks ago, now it won’t start. I checked spark and compression to find only 65psi. Have checked carby and valve seating plus piston and rings but found nothing apparently wrong. Now out of ideas.
If you have a spark, your timing chain hasn't jumped and there was not nasty noise when you last rode it, I would be looking at fuel first. Is the plug wet when you spin it over?
Hi guys, I fixed it. When I had the head off the first time, I filled the combustion chamber with petrol and it didn’t leak through the valves so I assumed they were seating ok. I also pushed on each follower and they moved freely. I purchased a valve lapping tool and lapped in all the valves as well as buffing the valves near the stems, and when reassembled it resulted in 140psi so problem solved. I can’t believe such a small amount of carbon on the exhaust valve seats could cause such a big drop in compression. Especially as it was working well on last ride, then just wouldn’t start a few weeks later.
Thanks for reading my post. Ian, Gippsland, Australia
Hi again, after solving the starting problem, I have now discovered that there seems to be no output from the generator/alternator. The first thing discovered was the red wire terminal at the rectifier/ regulator was badly overheated along with that part of the plastic plug being damaged beyond repair. Following the workshop manual hints I checked all connections along the red wire to the fuse and battery and all seems ok. Checking the resistance of the white wires to the stator I got 0.9 ohms between all combinations so I assume the stater is ok. Can I unplug the regulater and measure the output from the stator with the engine at fast idle? In the mean time I have ordered a new regulator.
Yes, you can unplug the reg/rec to check stator outputs. AC don't forget.
Corroded spade terminals will get hot - current trying to pass through a small contact area. Worth checking all the wiring terminal blocks.
Good luck!
Thanks moss proof, I just checked alternator output and it is healthy 30+ac so now it is a waiting game till the new regulator arrives later this month🤞.Then hope nothing else goes wrong. I rode an old bits a XT500 for 25 years without an electrical or mechanical fault and regret selling it to get an electric starter button.🤷♂️👨🔧🤐
