GS1000G engine into GS850 frame question

[Guest]

Hi Guys, A mate of mine in Scotland wants to fit a 1000G engine into his hard tail chop frame that has an 850G engine at the minute. what I was wondering was will he also need a 1000G wheel to keep the gearing the same and will the splines on the smaller engines driveshaft match the 1000? he is a bit of a mechanical numpty and just don't want him to call me saying"why is my bike slower" or "it wont accelerate right"!, am I right in thinking it's easier to just fit the top end of a 1000G to the 850G bottom end.Thanks for any info.Johnny

[Nessism]

Top end won't fit, the entire engine would though. I think you need the swingarm w/driveshaft. Or maybe just the driveshaft. Carbs are different. The rear end is the same as is the wheels. Some 850's have a points ignition but the 1000G will be electronic so that may be different too depending on the 850.

[wdavie]

If he needs to dispose of his 850 engine for a good price I know a man that would be interested.

[TheCafeKid]

I don't know for a fact, but I'm not entirely certain a 1000G motor will drop right into an 79-81 850 frame. Different cases likely meaning differences in mounting points. The earlier 850s either had a kicker (79) or had the space in the cases left by the kicker. That made the cases a touch longer. Or at least it looks that way to me. Again, I could be entirely wrong.

[Steve]

Actually, the '80/'81 850G and 1000G share the same part number for the frame, so it should fit just fine. You might need the mounting tabs from the 1000 to go along with the engine, but you should be able to swap the whole thing just fine.

For what it's worth: the '82/'83 850G and 1100G also share a frame number. It's different than the previous years, though.

.

[Flyboy]

It's a drop straight in job, he won't need anything extra.
Pull the 850 motor, shove in the 1000 motor, bolt it all up.
The gearing will be fine, they share the same final drive.
Been there, done that, more than once.

[SqDancerLynn1]

Actually the gearing is different, in the secondary gear assemble of the engine. For the good I will say ! 300-400 rpm decrease in cruising RPM. I have my 1000g motor in reserve to put in my 850 when the time comes. That is if it ever blows up. Currently almost 50k MILES, never been apart.. Depending on year you will need the later driveshaft, it has a larger bolt spacing, and the 1000 motor mounts

[nejeff]

It's a drop straight in job, he won't need anything extra.
Pull the 850 motor, shove in the 1000 motor, bolt it all up.
The gearing will be fine, they share the same final drive.
Been there, done that, more than once.

Will the exhaust bolt up?

[exdirtbiker]

Will the exhaust bolt up?

Stock or headers?
Here's a V+H 850G pipe on my 1000G. The rear attachment is the only thing you have to play with.
I don't know about stock pipes.

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