Fe550 weird clunking noise in bottom end

Hey guys,

I got a heap of gear of Taffy earlier in year and rebuilt my bike after cracking a piston.

As I was putting it back together I noticed when turning the crank over there was a slight clunk at 1 specific point every turn. Always at the exact spot. Didnt think much of it thougth once its all pulled up tight it will be ok.


So put motor back in and started it. Mades a airly loud knocking noise. Took it for a ride and it didnt go away. The magnet on oil plug had a resonable amount of metal on it. Changed oil and went for another ride. Same again.

So pulled motor other night and pulled it down. I thought it was crank end play doing something weird. But with cases split and crank in it still had the problem. So with elimination I ended up with ONLY the clutch basket and the main gear on end of crank. Thats with oil pump not connected and the idler to kick starter not connected. ONLY clutch basket. No plates or anything. Not driving the gearbox at all. Spin crank and there is a noticable clunk on 1 spot.

It seems to be the exact spot on the main gear every time too. Checked the gear and cant see anything or feel any lip etc with a screwdriver. If I put the gear on backwards it sits a bit more onto the shaft so only half the gear actually engages the clutch basket. No clunk. But slide it off a lil so whole face of gear engages and clunks again.

Seems to be on on the edge of the gear but i can not see a thing wrong with it.


ANY ideas at all. Tempted to just go buy a new main gear lol. Willing to try anything.

Thanks guys in advance
Matt.

Hi Paul

Thanks for the reply.

The first time I used the bolt in the front of case to lock the crank. But I must admit I did use a allen key jammed in to undo the clutch basket the first time before I made up a jig to hold it.


I thought I had some bearing blue but couldnt find it over the weekend. But the teflon tape is a great idea I will try that.

I have taken the gear off washed it throughly and marked with a texture where the tight spot is but I cannot for the life of me see anything wrong at all. Have scraped the gear face with a bit of copper wire and it feels just as smooth as any other tooth.


I have pretty much eliminated anything else though. If I slide the gear on but not all the way on so the last 2mm or so are not engaged its quiet as a mouse. And if i put in on backwards all the way these same side of the gear is not engaged and quiet. So that rules out damage to clutch basket. It HAS to be the main gear.

I will let you know about the teflon trick tomorrow hopefully. Just got home for a huge day at work and the shed is a long way from my bed atm haha.

yep as I only have the primary gear on and the clutch basket. I do not have the other gear on balancer shaft to drive the balancer. So when I do all these tested the balancer is not spinning. I will look it over though. I am baffled to what has happened.

Hopefully get some time tonight.


cheers
Matt