1980 185 race bike build

[Homeless Dave]

So a good friend of mine decided that he wants to rebuild theengine in his 1980 185. The engine is not original, but is rather an 84 200s engine. He wants to rebuild after the engine blew up due to having a wrist pin retainer clip scar the cylinder and seize the engine and ruining the piston and bore. the engine was already mildly built up with an xr200 cam, xr200 intake and carburetor, and full kerker exhaust . He decided that he wanted to leave a stock bore size of 65 mm, but go with higher compression piston. The Piston that had been used previously was a stock bore but 10.5 to 1 compression. My friend decided that this time the engine would be full race ready. He decided to go with a weisco 12.5 to 1 compression piston. As for a camshaft he decided to go with a web camshafts grind 232/172. this cam has valve lift of .438/.395. I believe that the compression ratio will require roughly 110 octane fuel. I will be doing a port and polish on the head as well as installing the new valve springs with titanium retainers. I am also in charge of the full final assembly of the engine. The clutch has already been upgraded with stiffer springs. The chassis is going to have some minor cosmetic things done as well as all new bearings, sprockets, and chain. We really want to find an old suspension kit for this trike, it would be awesome! we are just a couple of teens keeping the trike culture alive and are going for a machine that might have been raced at a local level back in the day. Any input as to other modifications would be greatly appreciated!

[atctim]

May I suggest the 30mm carb for this build. Also - larger valves really help these motors.

[ATC King]

Ever had a recoil handle forcibly ripped from your hand while simultaneously pulling your shoulder out of socket?


I don't know how much cylinder pressure that cam will bleed off while cranking, but a functioning decompression system would be a good idea. One good squirt of starting fluid and the successive backfire while y'all are trying to start that for the first time, and someone is going to need to learn to wipe with their other hand for a while.

[350for350]

Someday, I'm going to build a suspended 185 off of one of the 1980 models myself. The engine won't be built as much as his is going to be.

[Homeless Dave]

Thank for some input! We intend to try and use the decomp if possible, it made a huge difference even with the old 10.5:1 piston. I will also look into a 30mm carb, i believe the one he has is somewhere around 26mm? As for larger valves, we decided that it will be looked into but no decision has yet been made.

[Homeless Dave]

I want to correct a mistake from the original post, it is only 12 to1, not 12.5. We found out that the wrist pin was siezed into the rod so we are building a 200e engine that I had in my shed. he wants the low range and electric start. I swapped over the clutches already. have the piston installed. the dome on it is insane! hopefully I can finish it up tomorrow and maybe get the first fire up!