Where are the 8 valve 750 folks?

[Coady]

Some good info Postman Pat. Thanks for going to the effort of typing all that out.

Glad to hear the 850 mod is worth the effort. Got some 850 cylinders (not sure what year, fingers crossed...) and pistons ready to go when I get a spare weekend - just need one more set of rings.

It seems I too am hopelessly attached to my GS 750.

[slow_heavy_750]

Pat-

Awesome post, definitely gave me a few ideas. I think at this point im going to focus on shaving some weight. The front fender is already off (doesnt fit with the current tire on there.) Im just going to keep my eyes open for the 850 top end and see if I can find the parts locally (because im sure shipping would be rediculous.) I already plan on converting the chain/sprockets to 530, and ive also been keeping my eyes open for the 1100 swingarm, but so far no luck...

[Detroit Diesel Man]

Nice post Pat...thanks..alot of what you mentioned Ive done and am planning on a few more things...I get the "why not buy a new bike" line from people at work alot...but yeah I like the old GS's and I dont want a cookie cutter bike like everyone else has...thanks for the post and tips!


John

[cyclefvr2]

would a 850 jug punched to 1000, with a 750 ,ported /polished head,and smooth bores fit,and work?
hehehe

[dlanes]

I just picked up katana forks wheels and brakes for my gs. I also got 850 jugs and pistons for swapping on in the spring

[npntransistor]

1977 gs 750b

Can all of the 750 2v heads be bored to 850? If im understanding this all i would need are pistons and rings? How far over is that?

[67fire]

Don't have time to read ALL of this thread right now but,
when I made my 750 into an 850 in 1981, it was painless except for the fact that the Dealer told me that it couldn't be done! LMAO!!!
Also, if you use the 750 head, the combustion chamber is smaller and will help in boosting the compression ratio.
Just like when I used the '81 850 head on my Wiseco piston kit in my 1000. More compression.

Eric

[TeamDar]

Don't have time to read ALL of this thread right now but,
when I made my 750 into an 850 in 1981, it was painless except for the fact that the Dealer told me that it couldn't be done! LMAO!!!
Also, if you use the 750 head, the combustion chamber is smaller and will help in boosting the compression ratio.
Just like when I used the '81 850 head on my Wiseco piston kit in my 1000. More compression.

Eric

The combustion chamber size of GS750 & GS850 motors are the same size. 1979 cylinder heads have the same part #11100-45820 for both 750/850 engines. After 1979 there were no more 8-valve GS750's. All years GS850's use the same pistons #12111-45110. If you are going to use your 8-valve GS750 carbs then just use your 750 head. If you are switching to CV carbs then you need to use a 80-83 GS850 head with the large intake ports.

[67fire]

I stand corrected on the 750 and 850 heads.

The first one is a '79 750...



This one, is an '81 850 head that had a misunderstanding when the timing chain no longer wished to participate...



As can be seen by the carbon build-up, it was on a 1000 cylinder and block.
Thus, more compression.

Eric