Thin head gaskets and hi-po cams......

dewjantim · Post by **dewjantim** » Fri Feb 20, 2009 6:01 am

Hi guys. I am finally getting started on my 900 GTS. I need to know a couple of things. Does anyone sell thin head gaskets or hi-po cams for the spring motor (Steve ?). If I install the thinner gaskets do I need to also buy shims for the bevel drive unit. Thanks for any help you can give me......Dewey.

nottonight68 · Post by **nottonight68** » Fri Feb 20, 2009 6:13 am

i doubt you'll find a head gasket for a bevel anywhere -did you mean base gasket

steve

bobnorton · Post by **bobnorton** » Fri Feb 20, 2009 8:46 am

Hi Dewey, I dont think the cyl base gasket thickness has any effect on bevel gear and of course theres no head gasket only an o ring, however the gasket at the head of the bevel shaft tube is a problem if different from the orriginal, you really need a micrometer (£20 ok) to work out whats needed, The design of the valve gears is a bit exotic really and needs good understanding to set up well, a good manual will more than pay for itself or get someone experienced on bevels to help, mistakes willcost you dearly.

Post by **BevHevSteve** » Fri Feb 20, 2009 9:51 am

Dewey, only Orings between head and cylinder, no gaskets.

dewjantim · Post by **dewjantim** » Fri Feb 20, 2009 12:29 pm

OK guys, I figured that the Ducs had head gaskets like the other bikes I have worked on. I was wrong. Bevel drive engines are new to me and I am still learning. I have a couple of manuals, they came with the bike, but my mechanic has them. We are getting ready to start as soon as the weather breaks. I noticed that V two offers two different cylinder base gaskets one in .3mm and one in .5mm. Which is stock? It seems as though a thinner base gasket would also boost compression the same as a thin head gasket would. The result would be the same in both cases, the piston would travel farther into the combustion chamber, raising the compression. My mechanic has studied the manual and says that the design is pretty straight forward and should not be that hard. I keep hearing that the bevel engine is exotic and hard to set up. Is this for the desmo engines only or for the valve spring motors as well. If there is some secret trick to setting them up, please let me in on it. I ran across a whole bevel drive gasket set for $40. It is made by Athena, are these gaskets same as stock or better. And, Bobnorton, should I check the thickness of the gasket on the bevel shaft tube with these gaskets? If so, what should it be. Steve, are there any performance camshafts available for my valve spring engine or will I need to have one ground? Will the camshaft from the 750 Sport fit, or is it the same as the stock 860/900 cam. Thanks to everyone who has answered my post......Dewey.

wdietz186 · Post by **wdietz186** » Fri Feb 20, 2009 3:36 pm

Dewey,You should look around for some higher compression pistons. I think Wiseco still lists the 87mm piston for the beveldrives. Or call Syd's Cycles in Fla. Malcome may have some pistons available. As for cams Megacycle might be able to help you. But I think the gain from the cams will be slight. The ports are restrictive and bigger valves would be needed to realize any major performance gain. Even after all that a SV650 would still leave it for dead. The pistons will give you a nice torquey feel and make it a good responsive street bike.

dewjantim · Post by **dewjantim** » Fri Feb 20, 2009 4:58 pm

Thanks for the tip on the megacycle cams. I plan on getting stainless or titanium valves for the bike. Am going a few mm bigger on the intake, polishing the combustion chambers, polishing the exhaust ports, and cleaning up the intake ports while mating them to the intake manifolds. If I need to bore my cylinders, I will get the hi-compression pistons from either Wisco or Borgo, unless Syd's has them. Otherwise I will go with the thin base gaskets or shave the head a little. I don't know about that Suzuki leaving me for dead....... my 900CR with 75 horsepower would eat one alive.......hehehehe

......with about 70 or so HP I might be able to at least keep up

.......Thanks......Dewey

.

wdietz186 · Post by **wdietz186** » Fri Feb 20, 2009 7:23 pm

Dewey, Read Kevin Bracken's article on modifying his Darmah.. You can build a nice running bevel with pistons and careful assembly. But making it run even with your belt 900 is quite an undertaking. Keep in mind the cranks on these bikes can be fragile if stressed too heavily. And the rod sets are expensive. And sort of rare. The article is on this site under Articles Index.

bobnorton · Post by **bobnorton** » Sat Feb 21, 2009 12:34 am

If you change the cams its likely you will alter the bevel adjustment and need to remove the bevel shaft tube, if the new gasket is a different thickness to the old(most likely) this affects the bevel mesh and nip on the bearing collar , see what i mean!!!. Dont mess with things that work ok is the answer really,my little bevel was built by proffesional bike mechs and fettled by a Ducati racer before i bought it, It has taken me a long time to put right the stupid mistakes they made, you will need to engage brain more than is usual and go slowly. If the settup is good already you wont have half the battle i had.

abmartin · Post by **abmartin** » Sat Feb 21, 2009 8:50 am

A friend of mine decided to put more radical cams in his 860GT just before we were to leave for a long trip, then wondered why the bike wouldn't start. It transpired that aligning the dots on the bevels put the cams two teeth out. It worked well after that was corrected but I wouldn't expect miracles.

Bruce