Repairing a sprocket

[ScottT]

I have a front sprocket in a poor state, its it possible to weld it then reshape the teeth?
I guess it would have to be hardened later, has anyone tried this?

Dont suggest i just buy a new one, finding one is impossible.

Looking for ideas on how i can fix it, or perhaps you know of a company that can make me a new one.

[Commuter_Tim]

Ignoring the insane idea of repair welding a fucked sprocket...
Which bike it is for might help?
____________________
The above post is most likely nonsensical.

I ride a Bandit 600... badly.

[Teflon-Mike]

Some old Brit-Biks had rear sprockets cast integral with the hub, that may be a little difficult to replace, '-b-u-t' I believe that there have been specialists who have been milling them off and shrinking on new 'ring' sprockets to salvage the hubs for many years......

Talon Sprockets in Coventry used to boast that they would make specials to order for 'anything', and I suspect they still do...

So I am very skeptical of your aspersion that

[P.]

Mong. You'll find one. Don't weld it, don't try and make one. Buy one.

[Pete.]

Is the make of bike a big secret? The more info you give the better answer you'll get.
____________________
a.k.a 'Geri'

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

[Kickstart]

Hi

Another vote for getting one made. Not as cheap as one off the shelf, but not that expensive

What bike is it? Fair chance even if not specifically listed then it is shared with other bikes

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

[Ste]

[MarJay]

My telepsychic-o-netic-tastic abilities are telling me it's for a BMW F650 Funduro, which won't be impossible to find. However, seeing as you're not casting out the make and model of bike with your electronic internet telepathy I can't confirm that.

https://motorcycleparts-uk.co.uk/bmw-f650-chain-sprocket-set-94-00?language=en¤cy=GBP&gclid=Cj0KCQjwqvvLBRDIARIsAMYuvBGbe7FaP2rX3loV26jLyYecGaKcH9OBYYvluaxZDU0Q41YA8daP_x8aAmSXEALw_wcB
____________________
British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[ADSrox0r]

Aye I thought it was an F650 from the avatar-pic.

If so, certainly not that hard to get parts for and also swappage is possible with the Pegaso.
____________________
Current bikes: '08 VFR 800 VTEC(yo) , '07 ZZR1400 Winter hack: '95 Aprilia 650 Pegaso Currently lusting after: RC30

[stinkwheel]

IF (unlikely) you can't find one, they are usually a standard pitch and number of teeth (uless they are REALLY old, like pre-war).

You can buy blank ones.

Then all you need is to get the middle machined correctly. I seem to recall some companies just wanted you to draw round the old one.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[ScottT]

Sorry for not replying earlier, the bike in question is a 1931 James model C12.
They were only made for 2 years and so far my research has throw up there are two 1931 versions and one 1932 version left in the UK!
There might be others but from people in the know all i'm hearing is there are 3 of them, so ebay is not much use, i could spend a few years wandering around auto jumbles with my original sprocket to compare, but who has the time for that?

A few other bikes used the same Albion gearbox, but again finding spares is an issue.

So far my options are:
1.Weld new teeth on.
2.Machine the sprocket down and fit a outer ring with new teeth.
3.Or have a company make me one from scratch.

I asked because i just thought someone might have been in a similar situation and might be able to tell me about companies that will do options 2 & 3 as some of you have mentioned, thank you.


I probably should change my avatar, the beemer went 6mths ago

The bike in question.

https://classic-motorbikes.net/wp-content/uploads/2015/10/11564.jpg

[pompousporcup...]

wow, that was unexpected

option 3.

[MarJay]

Indeed. Have one made, or have an adaptor made up so a standard sprocket can be easily mounted.
____________________
British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[Pete.]

Yeah option 3.

John Hemmings Engineering
____________________
a.k.a 'Geri'

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

[grr666]

[Kickstart]

Hi

BMW F650 should be easy (same as the earlier Aprilia Pegaso 650)

But assuming that is just the bike in the avatar rather than one you need a sprocket for, B&C got a sprocket made for me when I needed one (for the Bimota):-

https://www.bandcexpress.co.uk/

JT Sprockets do give the dimensions of sprocket on their web site. Not easy to search through by dimensions, although you can do a fiddle and download all the pics to look at off line:-

https://www.jtsprockets.com/catalogue/

All the best

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

[lingeringstin...]

If you don't absolutely HAVE to keep it absolutely stock standard then I'd make an adapter to fit some modern readily available sprocket. For that matter I'd do the same for the rear and look at using bog standard 428 chain and modern sprockets that are readily available in all kinds of sizes.

This would of course piss off the purists but on the other hand it would mean you could easily ride the thing as much as you wanted without worrying about expensive replacement chains or sprockets.

Of course this it just the tip of the iceberg. Next thing you know you'd be looking sideways at modern carbs and newfangled pistons from other bikes. Then you'd be fitting 12v lights and a modified charging system, all very commendable but the purists would throw stones at you. I met a bloke at a bike rally once with a Vincent who had gone 12v and even fitted some kind of modern motorcycle electric starter. He said it did cause a bit of grumbling from the hardcore Vincent nerds, but the only thing I could see was that HE was at the rally on his bike and THEY weren't.

I've known some people with really old bikes and the ones I remember fondly are the ones getting used as opposed to the garaged museum pieces.

[Kickstart]

[ScottT]

Love the idea of having a boss made so i can bolt new sprockets on, but there just isn't the room. The sprocket is on the outside of the gearbox and the clutch is outside that, a rough guess would say i've got 2-3mm maximum clearance either side of the chain.

I'm not bothered about upsetting purists or have it exactly right, i just want to ride it, changing sprockets is going to be a long time away, with a rigid rear end there is minimal chain stretch plus when new it produced 2hp so its hardly likely to be chewing chains & sprockets (thats why i mentioned welding new teeth, i think they would last a year or so). If its lost half hp every 10yrs it will be producing minus 2hp now
Though having said that, when new it had a cast iron piston, mine at some point has been replaced with an aluminium one from the sports model.
Going off my other bikes mileage i guess when i'm using this i'll probably only do 300 miles a year, 500 max so a new sprocket should last a few years. I'm not in a rush to get it ready March next year is my target just really got some engine work to do and it will be sorted.

For the people who only know about modern bikes, on this i can change the ignition advance/retard on the move, i can also change the fuel/air mixture also on the move, full engine mapping at my fingertips!!! Lol. Plus it has a dry air cooled clutch like Rossi's bike, except his isn't made from corks!
Hand gear change is 1 forward, 2 back.

[lingeringstin...]

Could you spacer the clutch out a bit and use a longer push rod to get you sprocket space?

[ScottT]

[Teflon-Mike]

[Wafer_Thin_Ham]

I can't add anything constructive, but that is cool as fuck.

have you tried talking to Talon? They've always been very helpful IME.
____________________
My Flickr

[recman]

I popped in here kind of expecting some dodgy yoot wanting advice on how to re-secure a sprocket on an aging CG/YBR115.

Having one made sounds like way to go in terms of reliability.
However, I've welded and reshaped stuff at work which has lasted way past my expectations.

[Wafer_Thin_Ham]