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I need new sprockets for my 250 and MI only show a rear sprocket with 41 teeth and no front sprockets available. The correct size , I believe , is 45 rear and 16 front. Can anyone recommend a company that can supply some new sprockets,
thank you,
Dave.

Hello Buzby,

Yes the rear is 45 teeth, part 43.10.12 6 bolt holes

You can obtain one from B&C Express 01522 791369 , they have the drawing and the blanks in aluminium.
They made one for me earlier this year.

They cannot make the front, sorry but I don't know anyone who can.
Unfortunately it is not the same as any other easily available sprocket.

Mark

Try supersprox in Knighton Powys. As well as standard sprockets for regular jap bikes etc they have a custom make service. Probably not the cheapest way to get some sprockets, but if you have no off the peg supplier then these guys are a good place to try.

G&A

It looks like Supersprox are not in Wales now and have moved to the Czech Republic and Poland.

I will contact B & C Express first, I think.

thanks,

Dave.

Supersprox I think was Rodger Maughfling who was based on a redundent railway station on the Mid Wales Railway line next to a castlelated viaduct just down from Knighton and found it it cheaper to buy crap from the Communist Czech Rdepublic, a true blue patriot and sacked his gear cutter in the process, who then set up on his own, from whom I used to call in and buy blanks from him. When I last called into see him, he had a workshop in a timber yard premises near to Bucknell Station just up from Knighton. Very nice and helpfull chap, who has all the machinery for hobbing sprockets etc. The blanks used to cost less than a around £10 and made, not more than £20. The countryside round there would give you lot from flat East Anglia and the SW pulpitations the roads and scenario and lack of traffic is well worth a vist.

John Hemming Engineering Bucknell 01547 530759 (the Supersprox person?), re-toothed a Gilera 98cc gearbox sprocket for me. Not cheap and took a while, but it worked perfectly.

On the 2C/350 I run 520 chain now. Works OK with the 250 rear sprocket carrier. I wonder if a '350' gearbox sprocket would align OK on a 2C - or is the mounting 'slot' a different size anyway? In theory, I might have a usable 2C one knocking about in a shed.

You would have to work out appropriate gearing and get a rear made up based on a 14T front (though I did manage to acquire a 13T 520 version for the Forgotten Error). A quick sum suggests 40/14 wouldn't be far out.

I was thinking also that if you are getting a rear sprocket made then convert to 520. The shaft is the same fitting as 350. 14/40 is close to 16/45. I am sure the sprocket centres lines will be the same as both flat faces of the sprockets and hence their reference fitting are unchanged.
Mark

I thought it should probably work. I used to have 4 or 5 different alloy 520 rear sprockets that were made to fit the 2C or early 350 carrier, but I sold them.
The Forgotten Error was running 13/44

mbmm350s wrote:I was thinking also that if you are getting a rear sprocket made then convert to 520. The shaft is the same fitting as 350. 14/40 is close to 16/45. I am sure the sprocket centres lines will be the same as both flat faces of the sprockets and hence their reference fitting are unchanged.
Mark

Both give a 0.35:1 ratio, but which is better? 16 45 would probably mean less wear, but how about mass, inertia etc? Does it matter?

Thanks everybody for your help. I have made contact with B & C Express about a 40 tooth 520 chain sprocket.
I will report back when I have all the parts,

Dave.

have made contact with B & C Express about a 40 tooth 520 chain sprocket.

Makes sense.

To answer Mickey

250 2C 428H chain seems a little light weight and doesn't last that long. for sure less than 10K miles
I would hope a 520 would last longer and its quite close to a standard 350 setup
Since the engine cases are the same as a 350, @72 degrees
already confirms that a 520 setup fits a 250 frame/rear wheel

A deviation that doesn't help the original poster!
Years ago it ran with a belt, a synchroflex belt.
Without tensioner on aluminium pulleys and a modified clutch lever.
Unfortunately the belt was about 2 to 3 times the price of a 428 chain
and didn't last longer. The fundamental problem on a Morini is that
the available space for the front belt pulley is too small both in both width and diameter.
The design was entirely reversible if it didnt work out.
Mark

All finished now , a new rear sprocket from B & C Express, front sprocket from Mdina Italia (M190138) and a 520 chain. Thanks everybody for your help.

Hi, Good to see you gut sorted. I will be needing the chain and sprockets also as my 250 progresses. What was the cost of the sprocket and chain please and also do you have the part number or reference for the parts from B and C. Thanks

This is the description on my invoice "Renthal Rear Sprocket Blank 38mm Tooling Hole (100--520-40FS)" and the cost was £51.16 including P& P, so not cheap but it fits perfectly and looks good quality.
I phoned B & C and they were very helpful and they said they had the pattern for this Morini hub so no problem and I can recommend them.
I had a new DID chain on the shelf already, left over from some other project, so I can't say how much that would cost.
Dave.

Hi Dave,.
Thanks for the information, really helpful. I will get one ordered up. Thanks again,
Keith