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Need Help New rider & bike questions

csnowden

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Hi all,

Brand new motorcycle rider here after passing my Mod2 test a couple of weeks ago. My friend generously gifted me his unwell 2004 FZ6-S back in January before passing and said he suspects the final output bearing on the transmission has died.

The symptoms of it sound like a dying washing machine drum bearing when running at some speed on the road - it's not noticeable with it in gear spinning the rear wheel on the centre stand. He demonstrated this to me by riding past at a bit of speed, pulling the clutch and killing the engine so I could hear it. It happens on both acceleration and deceleration, the pitch of the whine increasing with vehicle speed not gear.

He said the noise started happening quite suddenly after he'd overtightened the chain by accident and then ridden a couple hundred miles before noticing and releasing some of the tension.

The rest of the bike is mechanically sound; it started on the second attempt with a fresh battery and some slightly old fuel after maybe 4-5 years of standing? And it seems quite rev happy too, we did have one hiccup during some garage tests where it would stutter around 4-5krpm but put that down to old fuel or moisture in the tank. Gear changes are all smooth and it goes through the gears happily - he never noticed that being an issue and hasn't been rough with the gears either. Suspension is all good, no leaking seals anywhere, just some rust spots and corrosion that you'd expect on a 21 year old bike run outside over UK winters! Wheel bearings all seem fine too with no lumpy rough spots in them.

My question is, how likely will it be that it is the output bearing just behind the sprocket? Especially with the chain being overtightened and ridden on. I'm happy to drop the engine and replace the bearing myself, it's just a bit of a faff and I would like a second opinion on it first before diving in and just doing it.

Thanks!
 
I recommend you take it to a local motorcycle repair specialist,to hear their diagnosis.
A difficult thing to diagnose over the internet,imo.
 
I recommend you take it to a local motorcycle repair specialist,to hear their diagnosis.
A difficult thing to diagnose over the internet,imo.
I was trying to avoid this as much as possible as currently the bike isn't taxed, insured or MOT'd so I'd have to put it back together to go do all of those things plus spend the money on all that. It is an option however, hopefully it would pass the MOT then I can ask the garage to take it for a short test ride at the same time to listen for the issue.
 
The bearing for the "Main Axle Assembly" can be removed and replaced fairly easily. There is a bearing housing that sits just behind the sprocket. Remove the three T-30 bolts that hold the housing in place. Then use two M6x30 bolts in the removal holes that are located at the 3:00 and 9:00 positions to back out the bearing housing. To ensure that the bearing housing backs out evenly, alternate turning the screws no more than 1 or 2 turns (once they bottom out) until the housing is free. The bearing is part number 93306-30525-00. Don't damage the housing...that part is NLA.

You may want to check the shaft run-out to ensure it still turns true.
 
I'm very much thinking it's 17 that will need replacing, along with 32 (the oil seal) as the service manual advises a new oil seal has to be installed.

I did try a screwdriver pushing against the shaft but I didn't notice any play — doesn't help I couldn't put the sprocket on and lever against that as the sprocket nut rounded out the other day when I tried to reinstall it (old bike, bits rusting...) and the new one hasn't arrived yet.

Having watched some videos of both FZ6 and R6 engines having the transmission rebuilt it doesn't look terribly complicated at all, just lots of parts to keep track of and I think I can access the bearing in question without having to remove both main and drive axles. Annoyingly the replacement OEM bearing from Fowlers is £65! Plus all the other replacement parts the manual says to replace along the way...
 
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