During the cooldown lap on the last race at Aintree the other weekend, the bike developed a fault where it stopped revving, and gradually died. With this the voltage was dropping until it stopped. I could smell some burning from the front so thought it must have been the battery eliminator that had died.

Anyway, having just finished rebuilding it this morning, tried starting (with a battery fitted) and it refused to, the voltage gauge was showing a massive current drain and then I noticed smoke coming from the PGM2.

I switched the power off, took the battery out, removed the PGM and went to find a spare. First thought was a dodgy servo but thats all fine (or so it seems).

Checked the loom for any cable damage, all ok.

Fitted the new PGM, started ok, valves moving as they should etc.

I'm stumped! I'm using the bike this weekend, and don't want to fry my last PGM. Any ideas what could have caused this to go?

Cheers
_________________
More **** two strokes than you can shake a **** stick at.

Hi 2Smoke
Some thinks that you must check and can cause the PGM to overheat and finally burn are these below :

Power valves cables not well lubricate or cable's wires in bad condition with no smooth movement.
Power valves cables wrong adjustment with too much tension,they need 0.5mm free play.It's better more freeplay than less.
Valves on the cylinder are not clean and they have carbon on them with the result of not smooth movement.

Check out these issues as any of them overheat and damage the PGM.

Could it be related to the battery eliminator ?

Honda changed servo motor wiring at some stage during MC18/MC21 production. While maybe not whats caused your fault, if you plug the "wrong" servo motor into the wrong harness your PGM will go up in smoke.
_________________
If I have to take the carbs off once more...

If the smoke that is put inside the PGM at the factory gets released to atmosphere,..

then the PGM stops working properly.
Apparently you cannot recharge them with fresh smoke.

TuckerBag wrote:If the smoke that is put inside the PGM at the factory gets released to atmosphere,..

then the PGM stops working properly.
Apparently you cannot recharge them with fresh smoke.

Totally agree !

I've checked the cables, all free, with the required amount of slack. RC valves as free as they can be (motor been rebuilt recently)

Stephen, the servo is the same as what's been on the bike since 2010, so don't think that is the cause.

Unless the battery eliminator suddenly allowed a load of power into the PGM?

I'm going to run a battery this weekend, hopefully it will be ok, if not I'm doomed for the rest of the season!

Fingers crossed...
_________________
More **** two strokes than you can shake a **** stick at.

Hi. I fabricate battery eliminators and use them on my bikes for several years.

For Nsr250 users I use capacitors rated at 20V. If there is an issue with the reg/ rec the battery eliminator dies in a matter of seconds and damage to the rest of the electronic circuits cannot occur.

I'm sorry to say that this is not the case if you've fitted a battery in there without first solving the issue as it will just boil the battery but current to the elctrics will not stop.
_________________
2t-racelab.com

Ok mate, well it's got a volt meter so I'll be keeping an eye on it tomorrow. I couldn't see how it could have been the eliminator but just clutching at straws. Possibly when it seized the front pot, the time it was still running was enough for the servo to overload the PGM, as the valve was a bit stuck after..

It's on its last warning now!



_________________
More **** two strokes than you can shake a **** stick at.

LOL

Don't do it!
The crank on my mc28 has died on the last race, so I'm pretty much in the same mood.
_________________
2t-racelab.com

Ok, found the issue.

Was monitoring the voltage during a session, and it was occasionally peaking at 19v. So disconnected the reg/rec and all's well now.

And it didnt seize!
_________________
More **** two strokes than you can shake a **** stick at.