Hot & Cranky issues

[kerryb]

My '83 standard with Vetter fairing starts great cold, even better warm, and only if I'm lucky when it's hot, (the engine that is). This is actually the second engine with the same hot-restart problem. When the engine is hot, the starter seems to lack the power to turn it over, like a dead battery but the battery shows 12.5 on the meter.
I've replaced the solenoid with a rebuilt one from a cb750.
I've rebuilt the starter, (cleaned, greased, new brushes)

If I wait for the engine to cool down some it will restart ok, but sometimes I don't have a 1/2 hour to spare. Luckily I was able to push start it last week alone on level road!

Any crazy suggestions are welcome. I bought a ford solenoid at NAPA. But they took it back when I showed it was faulty, so I missed a chance to try a solenoid that wasn't 30+ years old. I may try a garden tractor solenoid because it might be smaller

 

[joedrum]

a lot of times its the pole the starter cable screws to thats the problem ...seem to get connevtion in inside of starter...try lossening and retighten it .without hurting it... and move it just slightly ....

 

[slabghost]

With trouble like this that is my first move. As Joe stated loosen and move connections a bit and retighten. Starter is grounded through the mount bolts so I'd loosen and retighten those too.

 

[mcgovern61]

When I had hot temp starting issues, it actually turned out to be hydrolock in the engine from gasoline. Not enough liquid to stop a piston, just enough to increase the compression that the starter struggled to turn the engine over.

 

[Ansimp]

mcgovern61 » Wed Jun 01, 2016 6:24 am[/url]":2jjwmlr8]
When I had hot temp starting issues, it actually turned out to be hydrolock in the engine from gasoline. Not enough liquid to stop a piston, just enough to increase the compression that the starter struggled to turn the engine over.

+1
Also if your charge rate is too high the battery can be too hot and not have the same sort of reserve capacity. Once the battery cools its load capacity returns. If you have worn starter motor bushes this can also be an issue with a hot starter polling out ( hitting the sides of the field coils/magnets)

 

[AApple]

Mine will sometimes have that problem, too. It's hit or miss when the engine is hot. I have found that leaving the kill switch OFF, and hitting the start button will crank the engine over much easier, then switch to Run, and it'll fire right off. This is with both a worn out starter, and one that has just been rebuilt. Check the connections as suggested, then if it still acts funny, try leaving the kill switch in the OFF position, and see if it cranks easier. :good:

 

[kerryb]

Thanks, the kill switch idea sounds interesting. I was going to swap starters with the old engine but it had the same problem. Is there consensus that the solenoid might still be a big part of a solution. There aren't enough hills around here to always have one just in case!

 

[dan filipi]

I'm not down playing the stock carbs or anything but when I had the stock carbs on I had this same slow crank problem when hot. Even with a brand new heavy duty 4 brush starter. Since putting a single carb on it hasn't done this even once.
I honestly don't know why it would be but to me it seems carb related.

 

[mcgovern61]

I honestly don't know why it would be but to me it seems carb related.

My experience has been that the carbs can and do leak or at least dribble just enough gas when hot to allow the gas to expand in the cylinders while sitting. All the steel is heated up in the cylinder and it seems that the gas vapors do not escape. Sometimes, when the engine first fires up hot you can hear a single "knock" or "pop" from the vapor lighting off.

 

[kerryb]

Ok, the kill switch thing does seem to work, and a carb drip would help explain it.

 

[Ansimp]

Using The kill switch will help with an overfueling issue.

 

[mcgovern61]

Ansimp » Wed Jun 01, 2016 5:35 am[/url]":18wajm7f]
Using The kill switch will help with an overfueling issue.

Not only that. it also pre-lubes the engine by circulating oil before firing up.

 

[joedrum]

hmmmmmmm ...i guess this is somewhat true.....

 

[kerryb]

Tested and confirmed!!! Turn off the kill switch, get the motor turning over, turn on the ignition (kill switch) and she fires up right away. I'm thrilled...and I can understand how expanding gasses from drippy carbs could cause such a problem. What I don't get is how the starter has that much more juice to spin the crank just by turning off the current to the coils. Do the coils suck up that much power? I suppose I could push the starter button, flip the kill switch and twist the grip all at once with one hand, but it still makes me think I'll be stuck for 1/2 an hour in the wrong place some day soon

Thanks to all for the quick help.

just for fun...kb

 

[mcgovern61]

My opinion, (for what it is worth), I could not figure it out either. Then I learned about the whole wasted spark issue and that the coils fire a spark whether the engine is in power stroke or exhaust (if I have that right?). My theory is that the gas that is caught and expanded in the cylinders that are on compression stroke might be firing that little bit of gas enough to cause back pressure on the piston while the engine is trying to start.

Turn off the ignition and there is not enough gas vapor alone to stop the piston from coming up and ultimately clears out when the valves open.

I am not absolutely sure that is what is happening, but it seems to work well for me! :yes: :music2:

 

[Ansimp]

mcgovern61 » Thu Jun 02, 2016 5:51 am[/url]":1xn0xja9]
My opinion, (for what it is worth), I could not figure it out either. Then I learned about the whole wasted spark issue and that the coils fire a spark whether the engine is in power stroke or exhaust (if I have that right?). My theory is that the gas that is caught and expanded in the cylinders that are on compression stroke might be firing that little bit of gas enough to cause back pressure on the piston while the engine is trying to start.

Turn off the ignition and there is not enough gas vapor alone to stop the piston from coming up and ultimately clears out when the valves open.

I am not absolutely sure that is what is happening, but it seems to work well for me! :yes: :music2:

+1 :good:

 

[dan filipi]

Sounds sensible to me.

 

[wedoo2]

So, does he had a bit of a float issue?

 

[slabghost]

Not likely really. While the bike runs all 4 carbs are feeding a fuel mix. That mix is still in place at shut down. You turned off the spark not the fuel. So if it gets trapped as explained above the sounds more possible than not.

 

[wedoo2]

That makes sense, but I wonder why it doesn't happen more often? For that matter most any carburetor on these older bikes do that but just not enough to cause a problem. I maybe missed it, but was the starter dragging, or just wouldn't start when hot?