78 GS750 to 850 conversion questions

[Crazy_Russian]

so I'm trying to get a list of parts that i will need for this.
80-81 GS850 head
80-81 CV carbs (any other years?)
80-81 GS850 Cylinder block (any other years?)
80-81 GS850 pistons (years?)
what chain and tensioner do i need to use?
80-81 GS850 head gasket kit?

what other parts can you think of that i may need? Cams? Valve cover? Can ARP head studs be used?
p.s. PM me if you got any of this stuff and would like to get rid of it ;-)

[Tim Tom]

I'm just curious why a swap to an 850? I would think that if you were going for more power go all the way up to at least a 1000. The 8 valve engines had almost identical exterior dimensions and as I understand drop right in.

Also the 850 engine is a shaft drive only the 750s are chain. While I saw that you planned on keeping the 750 bottom end I still think it would be alot easier to swap a complete 1000 or even an 1100 motor in.

Just curious is all. Although I did see a few 850's for sale on the forum not that long ago, and I'm sure you can find parts around here somewhere if you REALLY wanted to go that route.

[7981GS]

CR, I did the same thing w-a-y back in '81?
Except that I used the 34CV's from a 1000.
Everything that you posted and the stock 750 chain/guides.
Also the CV manifolds for your new head.

Daniel

[Coady]

[QUOTE=Tim Tom;1391687]I'm just curious why a swap to an 850? I would think that if you were going for more power go all the way up to at least a 1000. The 8 valve engines had almost identical exterior dimensions and as I understand drop right in.

Also the 850 engine is a shaft drive only the 750s are chain. While I saw that you planned on keeping the 750 bottom end I still think it would be alot easier to swap a complete 1000 or even an 1100 motor in.
QUOTE]

The 1000 won't fit on the 750 bottom end. Off the top of my head the wrist pins are a different size & maybe the stroke length different too? Often the 850 option is taken if your 750 is worn and you need OS pistons anyway so it's an easy route to get the 850 parts and a bit of more power. Also the head is the same on the 79 850 to the 750 if you just want to swap cylinders/pistons only.

To put a 1000 or 1100 needs frame modifications which can become a much larger exercise entirely.

And by the way CR you can use the pistons and cylinders from 1979 onwards.

[Tim Tom]

Coady, I didn't know that. Thank you for correcting me. I feel like a bit of an ass now.

Apologies Crazy Russian for my miss-informedness.

[Coady]

Coady, I didn't know that. Thank you for correcting me. I feel like a bit of an ass now.

Apologies Crazy Russian for my miss-informedness.

Hey don't apologise, You were just asking a question . And as I said I'm just going off the top of my head anyway so good chance I'll be corrected too!

[Crazy_Russian]

850 swap is a direct bolt on, the reason for doing this is first of all, my engine has 31k on it and its consuming some oil now... second of all i can hear my #2 piston slaping at certain RPMs and load, not often, just once in a blue moon, but its time for a rebuild. also, im at 5500 feet, so i want to install CV carbs on it to get batter performance and fuel economy. so thats the reason for 80-81 gs850 head, while im doing this, might as well go bigger i also hate the carbs i have with a passion, they might be grate for someone who doesn't change 2000 feet withing an hour or two, but not in my case.
Daniel, thank you!
Tim Tom, its all good man :-)
Coady, Thanks you, that broadns my search by a bit:-)
but for the head i have to use 80-81 gs850 only, correct?