Maney 750 cylinder

Hi there, I had bought a nice alloy second hand cylinder made by maney , it's a 750 but with the 850 head bolts pattern( the bolts holes near the plugs are 1/8" outwards , mainly the rear ones.....????) is that common , or ...........?

I had one on my Commando but when the engine blew up it took the barrels with it. On mine the holes aligned ok with the head which had not been modified. It now runs 850 style 750 bored iron barrels. This a pic of the barrels before engine explosion. Sorry, no dimensions but might help you visually. Check with Steve Maney, he may be able to advise what you have.

It is pretty common to use the 850 bolt pattern with a 750 bore. It has the advantage of moving the bolts holes away from the bore for better strength and less bore distortion. I always used the 850 head bolt pattern on my 750 race bikes. Jim

Hi Jim and Keith, and many thanks for your quick replies..........so , I feel better now!
what do you do about the holes , just drill /mill or plug the previous one and drill /mill?
that was my first attempt ,but I had noticed that the new holes will be pretty close of the outside limits of the head gasket joint face (not sure of my english vocabulary on this one !!).
I had just collected my new crank last Sunday ( a friend of mine had done a steel flywheel, and then balanced the whole to the new Jim schmidt piston/rods, I had on the shelf for a year now...my budget is limited , now that I am retired!!!but the Seeley MK2 frame is in the shed , grace to my fellow Dan Parker in UK.............

You can plug and redrill the head. I usually locate the new hole and then using a mill I make the hole large enough to remove all of the old hole. Then I make a stepped bushing to bush the new large hole back down to the right size. The bushing needs to have a lip at the top to fit into a countersink. I make the bushing slightly too long and then when it is pushed through the hole it protrudes slightly from the deck surface. Thne when I resurface the deck it cuts it flush and leaves metal all the way around the bolt at the gasket surface. Jim

This is Ms Peel's Wovenhaven over ported Combat 750 head Ken Canaga made over size plugs then bored bolt holes and for 920 pistons to rise up to its wider squish bands. Ken put Timeserts in the stud holes. IIRC plugs just interference fit and fasteners hold in place. 'Puter crash lost his machining photo's but Ken has them and details if needed.

I posted a detailed set of photos on photobucket some time ago that shows how I did the conversion on Steve's (hobot) head. Actually, that's his bike's head, not Steve's. You can view them at

http://tinyurl.com/ysuvwb

Ken

I guess I should add that there are several ways to do the 750 to 850 head conversion. I like this one because there is no welding involved. I copied this technique from Steve Maney. It's how he converts heads for the wider bolt pattern for the 1007 cc engines. It sounds like Jim Comstock (comnoz) was using a similar techinique back in his racing days.

Ken

I'd forgotten how ugly the standard heads were. Thanks for that.

lcrken said:

I guess I should add that there are several ways to do the 750 to 850 head conversion. I like this one because there is no welding involved. I copied this technique from Steve Maney. It's how he converts heads for the wider bolt pattern for the 1007 cc engines. It sounds like Jim Comstock (comnoz) was using a similar techinique back in his racing days.

Ken

Click to expand...

And I still do one now and then, when I can't sell one of Fullauto' s new ones. Jim

I'd forgotten how ugly the standard heads were. Thanks for that.

Click to expand...

Ah shoot Fullauto, Peel head has fin welded back and over sprayed with Black Body Radiation coat and combustion surfaces with a ceramic dullness sheen.
Please show me yours to see what I'm missing out on. If yours allows surface for significant Singh Grooves, I may have to do $ome more upgrading. Not concerned much with extra flow, just anti-detonation fast burn small chamber provisions.

hobot