Broken Auto Decomp Bob Weight on Camshaft

Please has anyone got any info.

I have a 2003 FE650E and the bikes electric starting had progressively become worse until it would only kick. After fitting a new high crank battery etc i decided to inspect the auto decomp device. It looked worn so i decided to change it. After changing it the bike fired up every time on the button really nice. After about 15 starts the bike became difficuilt to turn over so i pulled off the rocker cover and noticed the decomp device had snapped off.! It never made any funny noise and the broken piece was easily picked out so no damage has occurred but i'm really concerned what has happened. Can it slide out off the spring and catch something.?

Any one had this or know why this has happened.?

Thanks for any info.

Lloyd,

I pressed the end bearing on until it just hit the stop on the shaft, there was a definite clearance in there but i must admit i never measured it.

I definitely checked the free movement of the decomp lobe, it was flicking in and out nicely.

I did not adjust the manual decomp as the play was 1-2mm. Would this have an effect.?

Thanks
Colin

Thanks Simon.
I have ordered a new one and a new spring for good measure.
It was not a tight fit, it span freely and nicely, maybe i got a naff one.!
Will try it again.

Colin

Guys, More info,

Here is a pic of the old black original decomp device and the new silver one that was supplied.



The black one does not have enough lift to allow electric starting. Even a brand new one of these is useless and will not work.

The silver one does have the right lift and the electric start fires all the time, but it broke.!

How fustrating this bike is........................i think i'm going mad.!!

Colin

I fitted another Silver one and its now perfect, starts all the time hot and cold. This one piece has totally tranformed the e-starting. The decomp lift on the silver one which has a different lobe profile is approx 0.5mm more, this is the difference between nice e-starting and no e-starting. This is my findings, i guess all e-starting problems are not this but in my case it was. My theory was i needed to replace it to eliminate it but it fixed it.!

Others will have different ideas and procedures but this is what i did.

After removing seat, tank etc and bits connecting to the rocker, remove the 7 allen bolts holding the cover. I used a rubber mallet to tap the seal free. No gaskets are used here just a thin smear of silicon. My cam chain had a rivetted link which you need to split, i got the engine on top dead centre on compression first to make assembly easier. MAKE SURE YOU HOLD BOTH ENDS OF THE CAM CHAIN AND PLUG THE GAPS WITH RAG when doing this, the cam chain and bits like to fall in. Then pull out the cam. Use a puller to remove the end cam bearing and then you can withdraw the decomp device.

I reassembled it all as per the manual. This shows timing it back up etc. Also make sure the little rubber o ring oil way seal stays in place, they easily fall out. I used a split link to reconnect the cam chain, this is what the dealer advised.

Parts i ordered were new decomp device, split camchain link & o ring seal.

This all sounds difficult but i found it dead easy to do.

The silver decomp lobes are quite difficult to get hold of now for some reason in the UK, importer DCR only stocks the black ones which are crap. You can add weld to the inside of the lobe to increase lift but i have not tried this so i cannot comment. Others more expert than me with Bergs have with good results i think.

Its worth investing in the later high crank battery - YTZ7S. I did replace my battery on mine before doing this to a huge YTZ14 high crank, mounted under the seat. It spins ok now.!

It all seems worth it now.

Guys,

Afraid i have no idea what the part number is, i just ordered a auto decomp bob wieght from the dealer. I got a sliver one first then a black one second time. I am certain the silver one is an updated part but i cannot get the info from importer DCR. He has the same black part for 2003 & 2004 bikes which are crap. DCR said he was taking this back to the factory, dont know if he has done this though. All i know is the silver one works great and the black one is *****. Hope he gets some updated ones in as a spare is always handy. Could add weld to the black one i quess and i'm sure it would be fine but cannot see why they dont stock the better part.!

Used a chain splitter to split the cam chain, same as a rear drive chain one. It didn't push the pin right out but was enough to do the job.

I used a 2 leg puller i got off ebay. Can use a 3 leg puller but you need to grind the hook ends flatter to get behind the bearing, them comes off easy. I used a vice to push the bearing back on.

Take your time and dont rush, its worth it.
Good Luck chaps
Colin