Wont crank when hot

[spoons]

Hi to every one,

Just woundering if anyone can sugest waht could be wrong with my 1999 l-8 model machine. The bike has done only 15000 miles and I have in the last 200 miles cleaned and balanced carbs, new K&N air filter, oil and filter change, new NGK iridium spark plugs and new coils. It starts from cold no problem and pulls and revs very well all day long.

The problem though is after it has warmed up to normal running temp and I pull over to say fill up, the bloody thing wont turn over as if the starter motor is stinking or not getting enough power. If I bump it off it starts and continues to run fine, if I leave it for 30 mins to cool down it cranks and fires up. Does anyone have any ideas it's starting to get embarassing bumping it of in the petrol station.

thanks again spoons

[extonyg]

if you do a quick search - top right - theres lots of threads on hot starting problems...seems to be a common problem but not everyone has found a solution...

[cargo]

generally the well documented hot starting problems dont include having a smelly starter.


Me thinks we need a little more detail.................


Cant think of anything in the starter circuit that would be so effected by a hot engine..............except perhaps that there is a bad earth somewhere ?? Even that is a long shot

[spoons]

if you do a quick search - top right - theres lots of threads on hot starting problems...seems to be a common problem but not everyone has found a solution...

I did look there to start with hoping I wouldn't repeat what others had asked. It would seem that most other people with a hot start problem still have there bike turning over but not firing, concluding some fueling problem.....My problem has nothing to do with fueling more the starter that acts like there is not enough power to turn the starter motor but when cool it starts fine. I was possably thinking there was a problem with the starter and the heat conducted to that from the engine, or the electrics did not give enough power for the starter motor. I hope this helps explain it better.

p.s. it has had a new battery 200 miles ago and sits on optimte that gives a green light after diagnosis time.

[Tirpitz]

Or possibly that the insulation is breaking down in the starter motor, which would certainly be more pronounced the hotter it is.........

[RedexRobB]

What sort of voltage are you getting across the battery terminals when the engine is running at 4k rpm? Id say its possible that the battery is being cooked when charging which can prevent it from delivering a decent current when you come to start it. Im also assuming it did this before you balanced the carbs etc?

[spoons]

Thanks for the replys guys, It has always done this and at first thought it was a battery drain problem so checked it was charging properly and it gets 14.2 volts at 4k revs so believe this is there or there abouts as per the garage manuel.

I didn't realise the starter had an insulation that could break down, is it a sealed unit or can it be checked?

[Tirpitz]

It's an electrical motor, so it's got to have some insulation in it somewhere, and there will be a lot in the windings which make up the armature. That might be where the problem lies.

It will be sealed I should think. I doubt if it's rewirable. Probably designed to be replaced if knackered. I think the best bet it to make sure you eliminate all other possible options, then when you are sure the starter is the problem get one from a breakers. Worst case scenario that doesn't cure it you can always sell it and get most of your money back.

Suppose you could test for resistance between the terminals of the motor and earth when cold and hot. They should give about the same reading. If resistance drops considerably when hot that's your clue. However, the resistance could be fine with the low voltage of the test meter but break down under the higher voltage of the bike battery.

[griff488]

Just a quicky but heat increases resistance in electrical circuits not decreases it.
i would agree that the starter motor needs replacing. You can usually get them apart but getting parts for them is a speciallist job. Sounds like the carbin brushes inside have worn out.

Cheers Griff