my trusty sherco 290 engine died today - had been running fine, no hint of anything wrong, getting spark, getting fuel, filter clean - it just died going up a hill - any attempt to start it just gives a single backfire 'pop' every so often and it's a backfire through the exhaust not the carb, fitted a new plug and it was the same

can the timing 'slip'? i'd have thought with CDi that would be difficult - my only thought is whatever is used to pickup the spark is at fauly

any ideas, has this happened to anyone else

Has the woodruff key holding the flywheel sheared? this would allow the flywheel to move and alter the timing.

Can't add to the thread, sorry, but I seem to read a lot about possible sheared keys on this forum... is this a common theme on modern trials bikes?

I thought once fitted properly, with the nut fully tightened, it would be very difficult to shear a woodruff key?

Am I right or wrong here? Just wondered.

Thanks

Peter

once fitted properly, with the nut fully tightened, it would be very difficult to shear a woodruff key?

but not impossible. Sheared my key once, had many of the same symptoms. Ran great put it away, tried to start it next practice out and just backfired and kicked back like a mule.

The timing can slip if the stator is in the process of giving up.

Unfortunatly, sorting this stuff can be a bit iffy.

I do not think you mentioned the year of the bike, as the ignitions do vary, however the basics are similar.

Clean and inspect the earthe on the cdi or coil. Ck plug lead and cap. Disconnect kill button or switch.

From here it helps to have a mates bike to switch parts such as cdi and or coils.

Then comes the pulling of the flywheel for inspection of the keyway! Yes, is it rare, but it does happen.

And if all is well there, you are pretty much down to the stator plate.

Edited December 14, 200916 yr by copemech

If you have the puller etc or access to them it's only a couple of minute job to check the key, I managed to shear mine a few years ago. Can't remember if it still had spark though

It's not unheard of as you've got a heavy flywheel trying to resist change & if things are sudden enough with the nut not quite tight then thats your problem

thanks guys, i'm leaning towards the key although the flywheel isn't loose and is still turning when i kick it over it may just be held on the taper, i get a strong spark every rev with the lightest of kicks so stator and coil etc are less suspect i just think it's sparking at the wrong time for some reason

i'll let you know

Tony

Tony, same prob happened on my sons '05 125, it was ths stator that had given up the ghost, it is a common problem on these bikes / ignitions, the pick up dies. The local dealer fitted a new stator, problem solved, then 2 yrs later the same thing started to happen again except in slow motion, this time it started to get harder to start and would kick back like a mule, not ideal for a 13 yr old. This time sent the stator off to Bradford Ignitions (in Javea spain, run by an english guy) for refurbishment much cheaper and he turned the whole thing round in a week from my posting in the UK to it returning to my house. Top service.

here is a link, will give you some clues as well as he is a serious bike ignition expert and really helpful http://www.uk-motoplat.com/

I bet you find this is the issue. The woodruff key is an obvious first check and an easy one, you will need a 30mm puller to get the flywheel off.

I would bet a five it is the stator though.

John

Ditto ,me too!

What age is the bike, those settings are no good for the earlier ducati electronica ignition

What age is the bike, those settings are no good for the earlier ducati electronica ignition

What settings?

Settings should have been readings- motoplat uk's readings are for leonelli stators

bike is a 2002 290 - there's a flywheel puller on it's way so i'll find out soon enough - having been a mechanical engineer for over 20 years i have realised what i knew all along - i hate electricity - me and electricity have an understanding..... if i don't touch it.. it won't touch me

thanks for everyones help and advice

Tony

Splatshop do exchange rewound stators if you need one a bit quicker.

They are very helpful too.