Was happily thrashing round Cadwell on my MC21SE and it suddenly wouldn't rev over 9ish-K (after 2 or 3 sessions). Got back to the pits and sussed that the powervalves had ceased to function.

Have tried another powervalve servo/motor which has not worked - tried this as the old servo was tested and I was told that 'the motor has bad commutation and the potentiometer is not changing linearly over the whole scale', so I decided it is probably shot.

Has anyone any suggestions on reasons for this and/or ways of trying to find/remedy this please? Summer is here (apparently) and want to try and make the most of what is left!!

Thanks

what it basically means is that the motor is stuffed, and the potentiometer (used to provide feedback to the PGM to say what position your valves are in) is also stuffed.



If you're really desparate, get the person that said "the motor has bad commutation....." to pull the unit apart, specifically the motor and the pot. Make sure he remembers what wires goes where.

Go into a hobby store with the motor and ask for a replacement. I think it is a 180 sized motor for an RC car.

Take the pot to an electronics store, and ask them for a 0-5k ohm pot, show them what you have. Make sure that the pot that they give you can be turned both directions, and it doesn't hit end stops.

Get the person that said "the motor has bad commutation....." to put all the bits back together for you and you're done

Or... the PGM has died!
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Andy.
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My first thought too.

Can you take the lid off the PGM and see if there's charring or even just a burnt smell?

Is the feedback pot linear? Might be logarithmic...
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Wow! Thanks so far!
Question - would the bike still run if the PGM was suspect? At Caddy I disconected the powervalve servo and wound the actual powervalves open so I could carry on with the day - the bike ran fine albeit a bit 'gurgly' bottom end!

Also I have actually tried another servo but no luck! Suppose either this servo has also seen its day, or it leads to the PGM being the cause. After all, the original servo was deemed to be a bit 'here and there' by the guy that gave the diagnosis!

Cheers!

No problem at all running the bike with an faulty PGM and pinned powervalves, other than the missing bottom-end you mention.
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Andy.
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One simply thing I could think of that noone else mentioned is......is the battery falt and or rooted!!!

I had my Dad's bike going on the weekend and the powervalves wouldn't move and we worked out that the battery was jsut dead!!!!

Battery is ok and holding a full charge.

I maybe chasing my tail on this one - it couldn't be anything to do with the 'pulse generator' could it? Been looking at the wiring diagram and just wondered........ If its a silly question then bear with me - just clutching at straws.

Really appreciate all the suggestions - thanks!

If a/the pulse coil(s) were faulty, the bike would either not run, or run very badly and/or misfire.

The RC Valves are integrated into the PGM-II, PGM-III, and PGM-IV boxes, but still work independantly from the CDI. This is why they can fail but the bike will still happily run.
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Andy.
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Hmmmmmm!
I have had the PGM and servo tried on a friend's bike, and guess what? The powervalves worked on his!! Aaaaaarrrgghh!! What now? We both concluded that it can really only be a broken wire somewhere, so new loom?

Are there any other suggestions maybe please??!?!?

(But I am quite happy its not the PGM thats fudged!!!)

thanks!

Try your carbs on his bike!

Check all the connectors, the earth points, and the state of the battery.
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Andy.
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Thanks for the continuing suggestions Andy! Carbs? Are you thinking throttle posn sensor or power jet solenoids?? Or am I barking up the wrong tree??? I won't be able to try the carbs on his bike as I believe it is set up to run a different air box. Am in the process of going through the connectors etc!
Many many thanks!!

T.P.S.

The solenoids will have no bearing on the operation of the servo... unless there is a short in the wiring maybe, but I don't have the time to trace the wiring diagram to find out!

You only need to run the bike up on the stand, not ride it, to see if the RC Valves are working -- the airbox won't make any difference.

Try bypassing the G.P.S. Maybe that is faulty.
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Have a look at the wiring diagram and get your multi-meter out. I'd start by continuity checking the wires between the PGM and the power valve motor whilst wiggling the loom!

Also check for short circuits to earth (chassis) from each of the wires.
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

OK thanks for that - will be checking the wires between the necessaries when I get my multimeter back!

Are the any published values of what multimeter readings I should be getting for the likes of the solenoids etc when they should be energising? From what I can understand, you can well get a reading but it may not be necessarily the correct one!

(After all this, I really am hoping it is just a broken wire........!)

Thanks once again!!