i had a problem on the last few laps of an enduro in sept. thought i had a stone go through the front pipe. sounded wrong and lost power. washed it off after the event and found the exhaust to be ok.when i started it up in the garage it would loose its lights now and then.i found out during a practice session last week that when i loose my lights i also loose me feed to my rc valve (with the cover off it does not "rock" the valve open when reved) now and then my lights will flick on and the valve then works (deffo all the same fault)
any others had this fault,
any help would be great thanks. john

its a mk3 by the way

Sounds like a Gremlin in Generating circuit.I don't know if the MK3 run seperate lighting / ancillary equipment coils, and ignition coils, the loss of power to all the ancillary equipment sounds like a clue.
It would be worth taking the generator cover of and having a sniff, a burnt out coil gives off quite a distinct odour.
You need to acquire a good quality magneto puller, [don't bodge it ,it's not worth the cost ] also a quality holding tool ,or an impact wrench, battery or air driven.
Being an intermittent fualt it's going to be a bugger to confirm, so it's also worth checking the the in-line connections on the way to the reg/rec unit , found usually under the air box , pay special attention to the three yellow wires connections , this is the three phase supply to the reg/rec .
West Country Windings , now perversely located in Herts i think ,can redo your generator with a quality rewind if required .
An online trawl should throw up several suppliers for Reg/Rec units .
Try a search on this forum ,from memory some one did a swap over recently.
Regards Mike

Hi John,
Hope I'm not too late replying, but I had the same problem on my mk1.

As it warmed up the lights would start to dim and the rc valve would slowly work it's way round until it was fully open. It was putting out about 4.5 volts.

Suspected the stator, and after a chat with West Country Windings, sent the stator to them for a rewind. £102 lighter the problem was still there. (Brilliant service from them though.)

Next in line was the regulator/rectifier. Bought a 2nd hand one off ebay, PROBLEM SORTED !!!

Worth trying the reg/rec before anything else ?

Best of luck with it.

Cheers, Steve.

fitted another reg rec..... fault still there, this is doing my head in !!
if the winding was at fault it would not come and go like it does.

[quote="shogunqwerty"]fitted another reg rec..... fault still there, this is doing my head in !!
if the winding was at fault it would not come and go like it does.[/quote]

I am no expert - but it could do depending on heat/vibration, if it is an intermittent connection..

I would think it is entirely possible that a winding fault would come and go. - Though again no expert .

Hhmmm could it be one phase going down ? in which case, it does sound more like an earthing / loose connection issue, Having a rewound geni,should have ruled out the charging circuit as the culprit, although the symptoms you have described would be a classic stator fault, ie loosing current as the unit heats up.
Regards Mike

its getting a rewind today so we will find out!!!!
i,ll keep you posted
i am racing on sunday maybe !!
thanks for the help lads