Motorcycle Repair: Bike will only roll start, kawasaki kz, oil leaks

Question
Hi Chris

I have a 85 kawasaki KZ 250 that will only start by roll starting the bike.

When i got the bike it woud start intermittedly from the electric start, now it  only backfires and not start from the electric start.

The bike will start straight away from a roll start and runs fine with a even idle. It does not blow any smoke except for a few small puffs when the engine starts and does not have any oil leaks or use exessive oil.

I have not compression tested the engine but aim to do so this weekend. I have done the thumb over the spark plug hole and it seems to have reasonable compression.

I have had the carbi apart and checked all jets and the diaphram all seem to be in good condition.

The spark plug is a sooty black color.

Should there be pressure coming from the oil plug hole on the gearbox as i have noticed pressure coming through this hole if you remove the filler plug while the engine is running

Any help would be greatly appreciated  

Answer
Hi Toby.

That sooty black on the plug means that the bike is running a bit rich.  If you have not tampered with the mixture, then the problem is likely to be the air filter may be clogged or the choke is stuck closed a bit.

clean the plugs and see if it will start with the electric.  Now if the bike has a problem turning over, then the problem is not related to the other issues.

Let me know what you find.
Good luck and ride safe.
FALCON