Front sprocket nut lost....near death experience!

[hopoffbaby]

Hi all,

Its been a while since I last posted on here. But last night I was riding home from work at a fair pace and all of a sudden I lost all power to the rear.

Upon the AA inspection the guy tells me the sprocket retaining nut is gone as too is the washer. He then continues to tell me that he cannot believe that the chain didn't jam and throw me off!

The sprocket had jumped off the toothed bit of the drive shaft and was free spinning on the remain inch of the shaft, held in place by the now wrecked clutch selector mechanism.

Anyway, long story short, I'm alive but my bike is limp. The thread on the drive shaft luckily looks OK so I think it may just be a case of replacing the nut.

Does anyone know the Yamaha part numbers of the retaining nut and washer? Or where I could order one from?

Thanks and regards,
hopoffbaby

[hopoffbaby]

LOL, how stupid of me!

Its a 2002 Yamaha FZS 600

Regards.

[Kickstart]

Hi

Have had this happen on several occasions. Once on a Cagiva (where the output shaft is very short, hence no chance the sprocket will stay in place when the bolt comes out), and once each on the FZ750 and FZR600. With the FZR600 I have no idea how long I had been riding with the nut missing as there was no sign of it at all.

Suspect it it causes damage the most likely thing to happen is the thread trashed on the output shaft, followed by a broken front sprocket cover.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[hopoffbaby]

Thanks for the replies guys,

Yamaha say the nut and washer are ~£3.50 each; not too bad.

I'm going to check the shaft again when I get home from work as it was dark last night and I want to double check. I pray to god I don't have to have the engine taken out etc. I was planning on selling the bike so that would not be good for my pocket!

Regards.

[sickpup]

Looking at worse case it's a lot worse than suggested.

Yamaha use a very fine pitch thread for the output shaft, people use a windy gun to do the nut up and strip the threads.

[hopoffbaby]

Hi guys,

I've had a look at the shaft and while it does look a little damaged I can still some thread on it. I need a second opinion though, I've attached a few photos for you gurus to look at. I hope its not bad news

Regards,
hopoffbaby

[mad4it028]

ide try and get a dia on there and retap it before fitting if i could find the right size dia
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always looking to buy bikes crashed ,unfinished projects,none runners pm me
currently riding kawasaki z1000 only bike ive ever loved

[Kickstart]

Hi

Looks wrecked. Only chance is that the damage is instead the remains of the thread from the nut. Doesn't look like it to me but the undamaged last thread does appear to be the same height so it is possible.

Unfortunately to properly fix it means replacing that shaft which will be an engine out and complete strip job. The nasty bodge job is to weld a replacement sprocket in place.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[cyberglass]

looking at the hole in the shaft.

You could possibly see how deep the hole goes if its deep tap it 8mm should do it. Then use a die to rethread the shaft then put everything back on.

Just incase the shaft thread fails again put put a screw covered in thread lock into the tapped shaft hole with a big washer on it.

Temp fix but cheaper than replacing the shaft.

you would need to keep a good eye on it though.
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DL650 Vstrom 2004
DRZ400S 2003
Yamaha R1 2005

[hopoffbaby]

mannn..... this is not sounding good I'm prob going to take it to the garage, any idea how much I'm likely to get bent over and raped for?

[Kickstart]

Hi

If they can clean the thread up not a massive amount.

If they need to do the job properly then ~£100 for gaskets and the like, ~£100 for the output shaft and then probably a days labour to drop the engine, split the crankcases (which means the top end off on most Yamahas), replace the shaft, rebuild the engine and put it back in the frame.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[lllN30lll]

IMO it would be easier to get a new engine.

https://cgi.ebay.co.uk/Yamaha-FZS600-Fazer-Engine-/370330954975?pt=UK_Motorcycle_Parts&hash=item563971ecdf

https://cgi.ebay.co.uk/Yamaha-FZS600-FZS-600-Fazer-02-Engine-Assembly-/120610421786?pt=UK_Motorcycle_Parts&hash=item1c14f0fc1a

https://cgi.ebay.co.uk/Yamaha-FZS-600-Fazer-01-Engine-/160478234267?pt=UK_Motorcycle_Parts&hash=item255d3f869b

https://cgi.ebay.co.uk/YAMAHA-FZS-600-FAZER-1998-2002-ENGINE-MOTOR-PARTS-/160472842386?pt=UK_Motorcycle_Parts&hash=item255ced4092

https://cgi.ebay.co.uk/Yamaha-FZS600-FZS-600-Fazer-Engine-Assembly-/120616096088?pt=UK_Motorcycle_Parts&hash=item1c15479158
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Turbo R1
CRF450R

[DrDonnyBrago]

Personally, I'd have a go at repairing it myself; given that if you fuck up you are in exactly the same position you started (i.e. probably easiest to get a new engine) so you have nothing to lose, part the engine out and stick it on ebay if you shaft it.

I am of the impression that an engine removal in that bike is rather simple.

[Ed Case]

Anything less than replacing that shaft is OUT, you've been very lucky indeed not to be a high-speed pedestrian once and I doubt you'd get away with it again. The cheapest way around it as suggested previously is probably to ring around the breakers to see if you can get, and how much, another lump would be. Sorry I know it's crap reading this but you've only got one life and it's worth more than money. If it was me and I was brassic I'd get a new front sprocket and get it welded on, if the bike's getting on a bit you've nowt to lose really have you ?

[Ed Case]

ps This welded-on sprocket business is not as unheard of as you might think, Laverdas have a habit when a 'sloppy' new one is fitted it can knock the splines of the output shaft all to Hell. There are several running about with this welded-up bodge and as long as you dont run your chain until it's totally, absolutely, positively phukt you could get 15000/20000 miles before your forced to do something about it.

[Pete.]

The shaft is a little chewed but not at the root of the thread so most of the damage is in the nut - I bet it's stripped bare.

A new nut will go on there and tighten to spec I bet. Some blue loctite will stop it coming loose again. It'll cost you less than a tenner to find out, I wouldn't hesitate to ride it if the nut tightened.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[warped one]

I had this happen to me on the GT, bloody scary when it goes. Mine went on a corner, with the GF on the back as it was cranked over.

I got mine picked up taken to a mates house then got towed home the next day by a mate on his bike.

What you want to do is go to a car garage and get a M18 fine thread bolt they will probably just give you one because they are used all the time on CV joints.

You really want 2. Use one to 'pick' the threads up and sort out the mashed part then use the other as you would normally. I did this and it worked for about a month until I lost my license.
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amnesia - Never in the history of usernames has one been more accurate. Warped indeed. You sir are a fecking oddball.