Back in 1984 i bought a Jet 200 with a 125 coversion on it from DyroSpeed in leeds.
This consisted of a std 125 cylinder with a sleeve around the spigot and the stud holes opend
to sit on the 200 stud spaces. I still have the kit !
Question is has anyone on here done it the other way round?
Reason is i have an Autisa kit and would rather fit it to 125 cases than waist a set of 200 cases !
200 cylinder to 125 cases
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As I am sure you are aware, there are 200 castings that have been bored to 150 spigot size and fitted with 150 stud holes.
I have taken a number of these casings, welded-up the stud hole and had the spigot hole re-machined to suit 200 or even 250 spigots.
Your request is a little different, but if you can locate one of these 150/200 castings you can utilise a technique that I have seen used to good effect.
Make some M8 studs out of aluminium and screw them into the stud holes using lots of top-notch loctite. Carefully file them flush with the gasket face. Then machine down the OD of the spigot of the Autisa barrel so that it slips into the mouth of the 150/200 casing. Now drill and tap some new stud holes using the Autisa barrel as a guide.
The new stud holes will cut into the ali inserts, but despite my reservations about this, the engineer who did it on his own engine found it worked.
I have taken a number of these casings, welded-up the stud hole and had the spigot hole re-machined to suit 200 or even 250 spigots.
Your request is a little different, but if you can locate one of these 150/200 castings you can utilise a technique that I have seen used to good effect.
Make some M8 studs out of aluminium and screw them into the stud holes using lots of top-notch loctite. Carefully file them flush with the gasket face. Then machine down the OD of the spigot of the Autisa barrel so that it slips into the mouth of the 150/200 casing. Now drill and tap some new stud holes using the Autisa barrel as a guide.
The new stud holes will cut into the ali inserts, but despite my reservations about this, the engineer who did it on his own engine found it worked.