850 top end differences

[Anonymous]

Ok, Im going to throw this out to the 850 guys cos theres people here who *really* know their 850's it seems.
Ive got a spare 850 cylinders/head of the hemi chambered variety, from a later gs850 (electronic ignition model), and my friend has a earlier 850 with the kidney shaped combustion chambers on it with somewhat dead cam bearings in it. Can he use my later cylinder head on his earlier motor just as a straight swap? or did the block spacing change with the motor revamp to that of the gs1000?
I think he'd like to know for sure, because he keeps asking me, and I keep saying "I dunno, try it and see"
Anyone?

[Anonymous]

Allow me to throw another wrench into the works. Bolt patterns are different. I believe it was 1982 and earlier would match and then 1983 and later would match. But the expert in this matter is Nick Diaz. So Nick, where its ya?

[saaz]

Interesting. I always thought the 850 was based on the 750 motor. Damn new fangled 80s bikes!!!

[Anonymous]

The 850 is pretty much a bored out 750. Ust be aware of the slight (and sometimes significant) changes in the different model years.

[Anonymous]

As far as I know, the GS850 engine is a mixture of both the GS750 (crankshaft and overbored cylinders) and the GS1000 (gearbox, clutch, etc).
Cylinder heads of 79 (breaker points), 80 and 81 (electronic ignition) GS850 models are exactly the same. Don't know for later types.

[Jay B]

If I remember correctly from a way earlier post the 79 850 was a bored out 750. 80 and later 850s were actually made to be 850s so they will be different.

[Anonymous]

the immortal 850

While on this topic, what can be done to the 850 to get a little more performance to it? Are there other cams made for these motors? How about pistons with higher compression? Any other mods to pep her up a bit?

[Anonymous]

Perhaps there are some differences between US and European types. For European types, the 79, 80 and 81 types have the same bore and stroke: 69 x 56.4 mm. Just an overbored GS750: 65 x 56.4 mm.
However, from 1980 up, Suzuki did use Mikuni BS 32 CV carbs on the GS850. Could imagine that this would affect the cylinder heads on the intake side.

Five String:
Wouldn't know of any modifications to get more power; I suppose you can get some ''hot cams", but that would turn the GS850 into a totally different machine. Don't think the frame will cope with, let's say, 20 hp more....

[Jay B]

The frame will cope because its the same as the 1100 but not sure that the shaft will. Nick where are you buddy? Your the expert here.

[Anonymous]

Didn't know that. Never too old to learn...

[saaz]

I have a vague memory that the GS850 had relatively mild cams, and putting 750 ones in was one mod, but I would check on that (unfortunately I had to get rid of all my old magazines with all that stuff in them). I would think the 850 is enjoyable as is. Put in oversize pistons when it needs it to improve the torque...simple and effective

[Anonymous]

Guys, be patient with me! I just got back from the Blue Ridge Parkway and the Smokies, swinging up to Cumberland Gap Nat'l Monument and West Virginia. The GK behaved superbly, as expected. Great trip, close friends, great roads, good food, wonderful weather for August, terrific pictures, everything (mostly) perfect. Did "The Dragon" and the Foothills Parkway.

First, IM not at all HO, Mark, don't try to turn the 850 into what it isn't. It's a sedate machine. Don't mess with it. You want more power, ride your GK. It isn't that the frame won't take it; after all, Jay is right -- the same 850 frame is shared by the 1000 and 1100. It's just that it's such a sweet bike the way it is. Plus there's hardly anything available for it in the way of performance parts. It has just 8 valves, mild cams, lots of overkill going into its design and manufacture -- all geared toward long service, not hot performance. Just enjoy it for what it is.

The 79 head is different because it's designed to accept the slide carbs. Only the intake is different. The rest is the same as that of the 80 and 81 models. In other words, take a 79 GS850, put CV carbs on it, a head off a 1980 GS850, then the cams and idle gear and valve cover off the 79, and everything should bolt up just fine.

The 1980 and 81 head is different from that on the 82 and 83. The bolt pattern for the valve cover is different; there are more bolts on the 82 and 83 than on the earlier models. You can take a head off a 1980 and put it on a 1982 just fine, for example, if you keep the same 1980 valve cover on.

The cylinder banks, pistons, rings, are all interchangeable and can retrofit or "forward-fit" each other. One can mix and match almost at will. For example, I bought a neglected 1980 GS850GT back in 1998. I took the carbs off a 1982 GS850 and fit them just fine, with slight modification to the choke mechanism.

If I'm wrong on any of thi
s, let us know.