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A stupid mistake.

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royhall:
Had a problem with my restored F2 that at first appeared to be a wheel balance issue. It felt jerky and bouncy at low speed, but strangely smoothed out the faster it went. Had the wheels balanced and the back was already spot on but the front was way out. Put it back together and it was still the same. Tried rear suspension adjustments but that didn't help either.

Decided to re-check the tyre pressures, and whilst doing the back noticed a scrape mark along the inside of the chain like it was rubbing on something. On closer inspection it was rubbing on the crankcase. So off with the transmission covers and this is what I found.

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Turns out the front sprocket has an inner boss that I had inadvertently fitted the wrong way round.

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Put it all back together and the jerky ride has gone. Narrowly averted total disaster there. Just goes to show, no matter how careful you are things still go wrong. At least I caught it in time and all is well now.

With a bit of luck this post will stop someone else making the same stupid mistake. ::) ::)

Trigger:
Front sprocket too big or 0'ring/ X- ring chain ???

royhall:
Well spotted Trig. O-ring chain. But turning the sprocket so the boss faces the engine (which is how it should have been) gives enough clearance. So all is well now.

By the way, the picture looks like the chain is scraping across its entire width. Its not, that's white dry chain lube.

hairygit:
Ouch! Looks like rust has breached the case hardening on the output shaft, which has then started wearing rapidly. Obviously going to need replacing, preferably before riding it again, because you could end up with no drive to the wheel at all, and that always happens miles from home and late at night, and if it lets go suddenly you could end up with serious engine damage (valves etc) through over revving if is pulling hard at the time. So sorry to give such bad news.

royhall:
Don't scare me like that Hairy. The output shaft is meant to be like that it's unique to the F2 & K7. It has a larger chain than the K models and the front sprocket attaches differently. Its stepped so that the sprocket tightens up against the larger diameter with a large washer and one central bolt. You scared the shit out of me there. :(

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