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racing a bevel head

Posted: Sun Jun 27, 2004 12:51 am
by Colin Linz
Has anyone had any experience racing a bevel head square case 860 – 900, post 1978 model engine? I am wondering how reliable they are, and what type of preparation would need to be done. Also what frames are available these days for one these engines?

Racing Bevel

Posted: Tue Aug 31, 2004 9:03 pm
by Mark Burling
I am just about to start building a 79' Bevel Drive race bike.

I have a modified crank, imola cams am looking at having upto 44mm inlet valves, I also have a mille oil pump, SS left side engine cover (to do away with starter). Chassis has had steering head steepened, swingarm shortened. I hav'nt picked a carb set up yet or for that matter sorted many details.
I'm told the crank and gearbox are the weakest points.

I have talked to several people who have built and raced these bikes and believe they can be reliable. This depends largely on how you ride them. I have only raced a Honda 125 Bucket Racer and a ZXR400 before. If I rev it like I revved these bikes it won't be reliable I think you have to ride a lot smoother.
I have an article from 1977 on the build of a 900 ducati that won the Superbike Production race at Daytona of that year.
If you had a fax number I could fax a copy to you.


Posted: Thu Sep 02, 2004 12:36 am
by Peter Mille
Be sure to use a non electric start chassis!!
To make room for the larger battery, Ducati weakend the chassis a lot!

Posted: Sun Oct 17, 2004 11:20 pm
by ducadini
A few of us raced bevels in nearly standard form mid 80's.
The Belgian scene of BOTT-racing wasn't really top, but I can say the beveleers were the only ones, who just had to adjust the gearing. No working. Couldn't be done either, with such mechanics inside.
We progressed step by step, modifying one thing after another.
Like Mark Burling, my Darmah ended with a headangle of 23°, and a wheelbase of 1420 mm, 16" front 18"rear.
I have to admit this is a bit too short and a wad to steep.
I raced the standard crankshaft, a stepped 38 mm, after 20K miles, and it only let go when slipstreaming F1's at 10000 at Francorchamps.
The engine was, apart from Imola cams, Malossi carbs and a home made exhaust, standard. Found that when I kept the revs below 9000, it was reliable enough, only lifted the heads after every race to check valves and cylinders. In the winter complete overhaul.
I know some bikes in the vintage are now faster than we were, but I think the tires and better prep (more$$$) do the trick.

Posted: Mon Oct 18, 2004 4:12 am
by Colin Linz
Thanks guys. I would have thought the swing arms would be too short even without shortening them. Did you keep the same offset with the steeper head angle? Was the change to a 16” wheel needed so the wheel would miss the engine?

Posted: Thu Aug 03, 2006 2:56 pm
by Mark Burling
Engine is now being built by Bruce Telford and head work being done by Collier engineers. Fitting 44mm inlet and std 36mm exaust. Running slipper bearing moded crank. Am changing swing arm by cutting a solid axle swing arm, slotting and fitting adjuster blocks (SS and MHR parts.).
Frams is down to bear essentails and I may do more strenthening b4 powder coating. As mentioned already has steeper steering head, also straight fornd down tubes and other minor mods. need to lift peg mount to where an SS chassis would be. Will keep posted.