Forum

[Anders F. R.]

I still have this idea in my head, to bore out a Model G 350 engine to closer to 400 cc. If I can find a suitable piston, of course, and a cylinder that will need reboring anyway. If I go from 70 mm bore to 74 mm, volume will ingrease from 346 cc to 385 cc. That might provide some more low rev torque. 


However, with a 74 mm bore, the minimum cylinder wall thickness will be only 3 mm. Is that safe?


And then there are those questions about the bottom end, will it take the (hopefully) increased torque etc. etc.?


Regards, Anders F. R.

[Geoffers]

Hi Anders. Our host, Mr Hitchcock, sells a replacement long-stroke crank which raises the capacity to 400cc with the standard bore. It's meant to give much-improved bottom end power which is just  what you're looking for.


T'aint cheap though...


Cheers,


Geoffers. 

[Anders F. R.]

I think I have seen that long stroke crankshaft before, but I can't find it now. Have seen a 350 to 400 kit, at least. 


Anyway: This is for the350 Bullet, isn't it? I have an older Model G, not a Bullet. Don't think it will fit.


Correct me if I'm wrong! I have a spare engine, and if I could have a long stroke crank in that one, without doing too much irreversible end potential damaging things to it, that could be interesting.


400 cc from a 70 mm bore. That will need about 104 mm stroke..... Really a long stroke engine!


Regards, Anders F. R.

[Geoffers]

My apologies Anders - it is indeed for the Indian 350 only     (page 43 of the current catalogue). Sorry mate.


Cheers,


Geoffers. 

[Dennis C]

Hi Anders


I have a BSA B31 350cc which I fitted a Triumph T140 piston to this brings the B31 to about 410cc and higher compression, the difference was barely noticeable which was quite a surprise, luckily I had a set of Gold Star Clubmans cams in the garage so I fitted these as well, now that really made the difference so much so that I changed the engine sprocket from 17t to 21t.


What was a 75mph bike is now a 95mph bike which will cruise effortlessly at 70mph.


But to be honest I think a 3mm cylinder wall may be pushing it a bit close, but I dont think the bottom end will be any problem