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Hi everybody.

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I'm Franck.

I run a little workshop in Lyon France specialized in vintage european and British  bikes.

I bought a 52 G80 to replace my 57 G80 with a 16M engine, as my daily ride.

The 52 's on the road now and I'm willing to finish turning the G80/16M into a trials bike.

I got fed up with track racing so now I want to "test" off road motorcycling.

I've been fascinated for a little while now by the "old school" trials bikes and races.

So here I'm am to enjoy the off road world and get a few tips to turn my bike into a nice, easy to use bike as I'm a beginner in off roading.

The bike already has 21" front tire, alloy tank, small seat...

But what sprocket to use? What are those tiny front hubs you see on vintage AMC trials bike, where to get a in between engine frame oil tank....

Hope to find some good tips here.

Also got a barn find 1970 B25 I'd like to give the same treatment.

Thanks in advance.




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Hi Franck,

I assume you want to turn your '57 G80 into something like this?  To help you with ideas I recommend you look at our digital magazine, ORRe which you can find by pressing the ORRe button on the home page of 'tc', where you will find the complete fully illustrated history of the AJS/M competition machines, plus many photographs of them in current action in classic trials.

When you have collected all your ideas we can then advise you where to find most things you will need.



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Hi, welcome to the forum, most of us are using Rickman type hubs using BSA Bantam/Tiger Cub shoes. Other suppliers are Alan Whitton and Gerry Minshall,easy enough to find if you want thier products. As for your gearing,we have recently discussed this,the general thought is that first gear needs to be around 25 - 1 from crankshaft to rear wheel.What can be difficult is to have a good spread of ratio's for trials sections,often road clusters have a large gap to second gear when the gearing is set for the base 25 -1 first gear. It depends on what gearbox you have or can get,if you can get hold of a Burman GB then you are in luck as Tricky Micky on her can supply you with some gears to give you a set of ratio's which will be spot on for trials use.If you have an AMC box it could be more difficult.The engines can be made to run like never before with the new Amal Concentric Premier carbs - with a couple of small mods,and also last well - unlike the originals. Sparks can be made more accurate and reliable with a new BTH electronic Mag.It all depends how far you want to go.

With your B25,you need look no further than Charlie Prescott on here and his excellent BSA Otter website.

Meanwhile,here is a pic of my old banger... 

IMAG0431 (1).jpg

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