'81 KZ440 won't hot start but will push start

Hello,

I'm only writing here as a last resort because I've read every forum I can find and none of them seem to solve my problem. The issue I have is that my bike won't electric start when it's hot but I can push start it which is a pretty annoying problem. When cold the bike starts up no problem and it has been idling at around 1,500. I have just rebuild the carbs, adjusted the valves, replaced the fuel filter, adjusted the spark plug gap, and cleaned up all the electric connections. When hot I can hear the engine trying to turn but it won't fire up. This is also with the choke off so I know that I'm not flooding the carbs. Today I got it hot, turned it off, and waited an hour and still wouldn't start up. It has to be cold for the electric starter to work. This is also a recent problem that has developed over the last 6 weeks or so - it didn't used to happen.
I've been thinking that my problem could be the regulator or the ignition coils not giving off enough power. I don't think that it would be stator because my battery is getting charged with the bike is running. I just wanted to see what some people had to say before I started buying new parts that I don't need.

Thanks!

What is 'hot' and why is it getting hot?


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By "hot" I mean after riding for 10-20 minutes and the bike is fully warmed up.

Also, I just bought a new battery because I thought the old one might be the problem but I'm having the same issues.

Would try to clean/lubricate your timing advance mechanism. If it is stuck in an advanced position it can cause the engine to be hard to start, due to too much initial timing. Just one of many possibilities.

When the engine is hot and you try the starter, does the engine turn over quickly - for example as quickly as it does when the engine is cold? Ed

It sounded a bit slower when starting before I replaced the battery, which is why I did. Now it sounds the same as when it's starting up cold but it won't start up.

GPz550D1 wrote: Would try to clean/lubricate your timing advance mechanism. If it is stuck in an advanced position it can cause the engine to be hard to start, due to too much initial timing. Just one of many possibilities.

Thanks for the tip! It was actually looking pretty corroded in there. I just scrubbed it down with a brass wire brush and put some WD-40 on the moving parts and springs. Unfortunately it didn't help - it still won't start up after it gets warm.

Would re-check the valve clearances to assure being within specs.

Good Fortune!

You may want to try this - when the engine is cold use a hair dryer to heat up the coils then see if the bike starts. If it won't start with a cold engine and hot coils the coils are the probable cause of the problem. It is possible that the coils are marginal and are not transferring energy efficiently when they get hot. When you push start it there is no electrical drain from the starter motor so more juice is getting to the coils. That may be enough difference to permit it to start when pushing it even though it won't start when using the starter. Ed