BSA A65 Devimead 750cc conversion.

[Kevev]

Hi all,

During the second renovation of my 1966 A65 Lightning I will be fitting the Devimead 750 kit that I bought from SRM in the early 90's. It has been packed away in its original box since I bought it and I have now finally got round to making use of it.

I have already had a second cylinder head ported and fitted with big valves ready for 32mm carbs. I have done this so that I can keep the original 650 barrels, cylinder head & pushrods in good order to keep with the bike should I, or anyone else want to put it back to original in the future.

My bottom end is currently with SRM having the crank re-balanced with the 750 pistons, along with other work to replace worn out bushes and also to modify the cylinder studs to stainless 3/8".

The Devimead cylinder barrels are approximately 8mm shorter than the original 650 barrels and use a shorter set of pushrods because of this difference.

I am wondering what the difference in height will do regarding the exhaust pipes. It's only 8mm but how will it affect the installation of the exhaust system?

My main stand used to rattle against the nearside silencer as it was and has left a mark in the chrome because of this. I really wouldn't want to end up with the silencers even lower down on the bike but I fear that this will be inevitable using standard pipes and having the cylinder head exhaust port 8mm lower than they were?

Am I missing something simple? Am I being stupid?

Do any of you have any experience with the 750 conversion and what were your results regarding the exhaust system?

Thanks again.

[ChrisG]

First of all, well done for having the crank balanced before putting it back together as with the different top end, the vibration could be much worse.
Re the pipes, none of them fit perfectly anyway. I would see how they fit when all back together and take it from there.
Chris

[johnjag]

I have a John Hill 750 conversion on my Spitfire Mk11. The bike was used to develop his alloy 750 barrels. The exhausts look to be original and fit fine but if John reads this perhaps he can confirm.

Regards
John.