Engine hot start problem

Hello guys, this is the situation so far (please help me with english!): electrical connection are ok but negative of start solenoid that was little slack. I fixed it. Now the problems could be two: can be the voltage regulator and I will check it out in my next ride or (the mechanic said) con be crankshaft bushing (is it correct name? in italian you can translate bronzine albero motore) that when engine is hot it inflates and start solenoid has not enough power to run engine. He said: if this will be the problem, sell the bike but I really would prefer to put a start solenoid more powerful. What do you think about? Thanks in advance

Pippo said:

Hello guys, this is the situation so far (please help me with english!): electrical connection are ok but negative of start solenoid that was little slack. I fixed it. Now the problems could be two: can be the voltage regulator and I will check it out in my next ride or (the mechanic said) con be crankshaft bushing (is it correct name? in italian you can translate bronzine albero motore) that when engine is hot it inflates and start solenoid has not enough power to run engine. He said: if this will be the problem, sell the bike but I really would prefer to put a start solenoid more powerful. What do you think about? Thanks in advance

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does your bike have the headlight relay modification to save from overheating the ignition switch?
Putting the larger starter motor on the OEM is a easy mod, larger cables especially the ground/earth cable helps. Its amazing how many people lately have solved their starter wows by putting a new starter relay in.

warp9.9 said:

does your bike have the headlight relay modification to save from overheating the ignition switch?
Putting the larger starter motor on the OEM is a easy mod, larger cables especially the ground/earth cable helps. Its amazing how many people lately have solved their starter wows by putting a new starter relay in.

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What? Never heard about this problem!!!

Pippo said:

What? Never heard about this problem!!!

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Oh ya its been around almost as long as the early Rockets. So muchbjiuce goes the the ignition switch it gets hot enough to melt solder and eventually the white ground wire will detatch.

What about the gear position sensor? Not much help just throwing out idea here. However, I recall there was a discussion about the sensor going bad and affecting other sensors in the start-up sequence (kickstand, clutch, throttle position, and kill switch). Since that gear position is on the engine (along with the kickstand) it could be affected by heat.

Pippo said:

Instruments and headlight are on. When I press start it is like battery is completely down, no lights and instrument points go crazy

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So pressing the start button shuts off the headlights... that's suppose to happen. Do they come back on when you release the button? This should happen with the bike cold and hot. Is it happening?

You stated when you press the start button, it's like the battery is completely dead (assuming with the bike hot). If so, when do the lights and accessories come back on? Time line???

Your mechanic stated the crank main bearings may be tight has a valid point but in all the years I've been on this site, have never seen it. Highly improbable.

Why would you assume it's the voltage regulator? What is the voltage with the bike running (over 14 volts)? Then it should be ok. What is the battery voltage with the bike shut off? Should be above 12.6 volts and closer to 13 at rest fully charged. What does the battery voltage drop to when you press the start button (cold and hot)? Big voltage drop means high load or defective battery (no capacity, sulphated cells). Low voltage drop means bad connection somewhere (or defective battery poor internal connection in battery).

In all the years I've been involved in the automotive/heavy equipment world, "Hard start when hot" issues were related to (in no particular order); poor welds on the field windings inside the starter, timing too far advanced, improper end play on the crankshaft (very seldom), defective/gummed up starter solenoids, improperly shimmed starters, bad connections at/in starter/relay/solenoid (usually this one) and even the odd defective battery.

You need to isolate each component starting with the simplest. I'd lean toward the connections at the ignition switch, relays and solenoid first.

welcome from arizona

Gregger said:

So pressing the start button shuts off the headlights... that's suppose to happen. Do they come back on when you release the button? This should happen with the bike cold and hot. Is it happening? I will check

You stated when you press the start button, it's like the battery is completely dead (assuming with the bike hot). If so, when do the lights and accessories come back on? Time line??? That's a problem, because bike starts again after half hour but last time i found battery down the day after as well

Your mechanic stated the crank main bearings may be tight has a valid point but in all the years I've been on this site, have never seen it. Highly improbable. I really, wish, thank you

Why would you assume it's the voltage regulator? Because I have idea that it don't charge battery correctly. Furthermore last year after a ride bike did not start, I checked battery and found positive pole melt! What is the voltage with the bike running (over 14 volts)? 14.10 Then it should be ok. What is the battery voltage with the bike shut off? 12.88 Should be above 12.6 volts and closer to 13 at rest fully charged. What does the battery voltage drop to when you press the start button (cold and hot)? No drop with bike cold, I will check with bike hot Big voltage drop means high load or defective battery (no capacity, sulphated cells). Low voltage drop means bad connection somewhere (or defective battery poor internal connection in battery).

In all the years I've been involved in the automotive/heavy equipment world, "Hard start when hot" issues were related to (in no particular order); poor welds on the field windings inside the starter, , improper end play on the crankshaft (very seldom)Can it be fixed?, defective/gummed up starter solenoids, improperly shimmed starters, bad connections at/in starter/relay/solenoid (usually this one) and even the odd defective battery.

You need to isolate each component starting with the simplest. I'd lean toward the connections at the ignition switch, relays and solenoid first.

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Thank you for your help

Pippo said:

Hello guys, this is the situation so far (please help me with english!): electrical connection are ok but negative of start solenoid that was little slack. I fixed it. Now the problems could be two: can be the voltage regulator and I will check it out in my next ride or (the mechanic said) con be crankshaft bushing (is it correct name? in italian you can translate bronzine albero motore) that when engine is hot it inflates and start solenoid has not enough power to run engine. He said: if this will be the problem, sell the bike but I really would prefer to put a start solenoid more powerful. What do you think about? Thanks in advance

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This will work but a whole new starter is just as expensive and easy to install.

I think I paid around $100-$115 for a 1.4 kilowatt starter at AutoZone. There's a thread here in the stickies.