Question about overheating and battery drainage

[Ulies99Kat]

I couldn't find a proper answer to my question within the search so here it goes:

I have done everything possible to keep my (new to me) 99 Kat in tip top shape.
New battery, new chain and sprockets, new fluids (all of them), fixed my broken faring clips, new spark plugs, carb cleaner, 91 octane gas....the list goes on....

Every so often, if I sit idle for longer than a minute or two after the bike has been running fine, it may stall for no reason then refuse to start again right then and there. I would need to either jump start it or jump the clutch in 1st gear to get it back running. Somehow it seems that my battery is being drained by it sitting idle too long.

Is it possible that its overheating and vapor locking (i'm not too familiar with that subject. but I've read about it a bit) or could it be a faulty (albeit new) battery??
How do I go about diagnosing the issue?? Any sugestions will be appreciated.

[05RedKat600]

Try running 87 octane like it's supposed to have. 91 octane essentially makes the mixture rich, especially in the heat down there in Florida. Also, the higher octanes burn hotter. Your kat was designed for 87 octane, and it's jetted for it too. Try it in your next tank.

[Kreylyn]

Make sure your also not using the choke at all when hot. Instead, you might very sligthly give it throttle to further lean out the mix some.

Choke adds fuel only.

Throttle adds air only.

Just to clarify...

Krey

[KatanaGSX92]

Try running 87 octane like it's supposed to have. 91 octane essentially makes the mixture rich, especially in the heat down there in Florida. Also, the higher octanes burn hotter. Your kat was designed for 87 octane, and it's jetted for it too. Try it in your next tank.

I've done a lot of research on that particular subject and have found that the octane rating has nothing to do with burning hotter or colder. Higher octane gas burns slower and can be compressed more before it detonates. Running higher octane fuel in an engine not designed for it means that some of the fuel could still be burning as it passes through the exhaust valves. Running octane higher than 87 on a kat is just a waste of $$.

As far as the battery being drained when the bike is warm, have you actually measured the battery to see if it has drained? It may not be. If you let the bike cool down for 15 to 30 min, will it start normally? If it does, its not the battery. It could be a poor ground wire connection. Heat increases resistance and may be enough to prevent the bike from starting. It could also by lack of sufficient Cold Cranking Amps:


Some engines are just harder to start when they are "hot". The Hayabusa (my current ride) is notorious for being hard to start when it is hot. As Kreylyn mentioned, the trick is to open the throttle just a bit when starting the bike. That usually does the trick for me. But, it does act like the battery suddenly doesn't have enough juice to start it up.

I have recently overcome that problem by going with a higher Cold Cranking Amp battery. The stock battery on the busa has 130 Cold Cranking Amps. The new battery has 410 Cold Cranking Amps. Even Hot, starting is no longer an issue.

I know you said you have a new battery, but is it the "right" battery? Some of the lesser expensive batteries also have less CCA's. If you've performed the first test and determined that your battery is not actually drained, then another test would be to run the bike like you have until it's hot. Then jump the battery with your car battery (engine on the car must be off!!). If the bike starts right up even hot, its possible that you may just need a battery with more CCA's.

[Ulies99Kat]

Awesome feedback fellows. I do appreciate the input. I will finish this tank and start using 87 from now on and save a buck or two. It has t been hot enough here in southern Cali to attribute heat as a factor yet. We haven't hit 90 as of yet. Now how do I go about checking for a faulty ground? You are right, if I sometimes (not always) let it sit for a while, it will start up again after stalling. As far as the battery goes, it wasn't a cheap one but I wasn't aware of the different types. I'll look into that. Thanks again!!