I bought a 2009 sherco 290 with a engine knock. I was told it needed a full rebuild. I took of the clutch cover as I could feel the gear lever spring had snapped. I found the snapped piece had gone between the clutch basket gear and the small gear that drives it and chewed up a tooth so every rotation it would knock. I managed to file it down a bit but to get it running smooth I had to file a bit much and now there is a bit of slack between both cogs and now I have a new knock. If it possible to put some weld on the tooth then file it down until it's smooth and knock free or do I have to spend £260 on a new one ??

A replacement from a breakers is your best bet

Sorry to say it but unless you can put up with the noise you'll need to replace the gear, it shouldn't be welded as the gears are case hardened & you'll just end up with teeth that could snap off causing a lot more damage

It could be worth looking on ebay for a clutch basket from a breaker, part number for the gear is the same from 99-2010

I thought as much. Iv not actually had it running since I filled it down but I might try it tomorrow

try this guy, ebay item number 301444547591 he had a sherco he was breaking, i wanted a water hose, he wasn't advertising it but i emailed him and he had got the exact part with the sensor, it went strait on, if he has got what you want he will probably ask you to say a price so start off low.

The small gear is inexpensive.

Yes the small gear is only £45. But the large gear is £220 or £260 with basket

Yes the small gear is only £45. But the large gear is £220 or £260 with basket

I presume you paid accordingly when you bought the bike? Nothing lost then, fix it correctly, and throw in some Viton crank seals from splatshop while you are there!

Still cheaper than a complete teardown and rebuild with bearings and rod kit!

call this guy, he will definitely have one in stock . http://www.allensusedtrialsspares.co.uk/

I think I got it very cheap for a 2009 290. It's not without issues tho. It needs the rear shock rebuilt. New rear mudgaurd. Linkage bearings and this engine problem. Does the engine not need split to do crank seals ?

To do seals the cases don't need to be split, I've never replaced just the seals because I've always been doing main bearings at the time but they do fit from the opposite side of the cases from the bearings

Normal way to remove them with the motor assembled is to carefully wind a self tapping screw into the seal & use vice grips or similar to pull on the screw to remove it

Ah rite I always assumed it needed split. I'm going to try running it the way it is with the filled down tooth to see what it's like. Hopefully my order from splatshop will be here tomorro

Had one the same and tried fileing down the gear and using a new small gear, it still knocked, apparently distorted the tooth enough to do so, although could not really see it.

If you pop the small gear off, the seal pops out easy with a little lever, I use a small dent popping slide tool to break the gear loose off the shaft, don't take much, but often more than prying against the case will get you, as you will damage case.

Let us know how you get on.

All my gaskets and seals came today so I got the engine built back up. You can slightly hear the worn tooth on idle but on throttle it's completely gone. I think the clutch may be slipping but Iv still to test it. I also need to replace the small end bearing but so far so good on my £180 bike . Iv got a video of before and after if anyone is interested. It's YouTube links

http://youtu.be/nivHDCwonQ0 (before)

http://youtu.be/p2rWbHlHeUk (after)