750 to 850 conversion who has completed the job?

[rwcfrank]

I am in the process of running through pages and pages of information regarding swapping the 850 jug and pistons on my 2V GS750. I PM'ed a few people who have done it but I want to be sure I get it right the first time. I plan to take some pictures and post a tutorial in the hopes of helping other members. So far I have purchased an 82 jug with pistons and wrist pins in great shape. I am having my stock 750 head rebuilt and milled a bit (maybe 10 thousanths). I am still trying to figure out which base gasket (750 or 850) and head gasket (750 or 850) to use and is there anything else I need to know about other than grinding the bottom end for clearance? Any help or comments are greatly apreciated!

[7981GS]

Just use the 850 parts including the O-rings.
Why would you have to grind anything?
It bolts right up.

Eric

[TheCafeKid]

Just use the 850 parts including the O-rings.
Why would you have to grind anything?
It bolts right up.

Eric

No it doesn't.

Only the '79 jugs bolt right up. '80 and on require some relief grinding of the cases to get the jugs to seat. I'm not sure exactly where, as I've simply hunted '79 parts to avoid this. But someone had a thread on it. It's relatively minor, from what I understand however.

Oh, one thing that may cause a problem yet still, the 82 on 850 cases were a completely different case than the 79-81 cases. I don't know if this will cause you problems or not...

[7981GS]

How does it feel to be wrong and give advice of things that you have NO PERSONAL EXPERIENCE WITH?
It bolts right up and requires NOTHING to be ground.
Is that clear?
BTDT myself!

2-valve engines ONLY.

Apology accepted.


Eric




BTW, she's back...

[rwcfrank]

Today I got the cylinder (81) onto the 750 lower end. I suppose it would have gone with no clearancing if I forced it but the clearancing was definetley the way to go. I had to take off about 3/16ths from the lower cases but once that was done it slid right on.

[OLDENUFF]

I installed an 80 850 top end on my 79 750 lower and had to grind slightky to get it down that last 1/8". Job was a piece of cake.

[7981GS]

I put mine together in 1980 and required ZERO grinding of ANY kind.
What gives?

Eric

[salty_monk]

Eric maybe your hammer is bigger than theirs

[OLDENUFF]

I understand the only drop in 850 is the 79 model year. All others require a bit of grinding.

[TheCafeKid]

I put mine together in 1980 and required ZERO grinding of ANY kind.
What gives?

Eric

Apology accepted.