A stupid mistake.

[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.

[hairygit]

Sorry about that Roy, didn't read the whole post, just looked at the pics! Any other Honda four what I said would be true, seen it a few times where bikes have been stood for a while and the case hardening has broken through, and on more than one occasion I've had desperate calls from people at gone midnight because they've lost all drive in the middle of nowhere . So glad for you that it wasn't the case. But, before rebuilding your 350, do check that shaft for corrosion, far easier to replace if necessary before putting the engine together and in the frame. Oddly enough I've seen a few very rusty ones for sale on fleabay lately, and some mug bought them! (Although it may have been someone like Ashimoto, with the ability to clean and re-harden properly)

[UK Pete]

Blimey roy these bloody old bikes are a constant battle, always problems of some sort, wether self inflicted or not
pete

[royhall]

Sorry about that Roy, didn't read the whole post, just looked at the pics! Any other Honda four what I said would be true, seen it a few times where bikes have been stood for a while and the case hardening has broken through, and on more than one occasion I've had desperate calls from people at gone midnight because they've lost all drive in the middle of nowhere . So glad for you that it wasn't the case. But, before rebuilding your 350, do check that shaft for corrosion, far easier to replace if necessary before putting the engine together and in the frame. Oddly enough I've seen a few very rusty ones for sale on fleabay lately, and some mug bought them! (Although it may have been someone like Ashimoto, with the ability to clean and re-harden properly)

First thing I did was double check against an F2 output shaft for sale on eBay and that was stepped the same, then straight to the 350 to check that. Fortunately its like new (weird really as the rest of the bike has been a mess). See what you mean though about the case hardening as the 350 sprocket isn't trapped tightly and can move slightly. Shouldn't be as bad on the F2 as the sprocket bolts up tight and cannot move at all.


Your right Pete, they can be a pain. Part of the fun though (sometimes). Cant blame this one on anything else though, my error completely.

[Spitfire]

That's one for the memory bank !

Cheers

Dennis

[royhall]

Just been to the Isle of Man on the old Blue F2. Whilst there it started to make a knocking noise that I could also feel through the left footrest. When I got home I had a good look at the chain and sprockets, they seemed worn and I thought they were causing the issues. I have had this bike for a few years and done thousands of miles without a hint of a problem until now.

When I took the covers off guess what, the PO had fitted the engine sprocket the wrong way round. It had really had a go at the crankcases.
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Guess this is a very common thing. If your running an F2 have a look at the inside of the chain for signs of wear. You never know.
New chain and sprockets now fitted and no lasting damage done.