850 top end on 750

[jabberjoe87]

If one were to put a 850 head and top on a 77' 750, would different carbs be needed or just rejet and tune as necessary, also, what about the exhaust system, could that be reused. Also, what year would fit on the 77

[Nessism]

My understanding is that you can use a 850 cylinder barrel and pistons, along with everything else from your 750.

[jabberjoe87]

This is getting interesting

[Big T]

Any year 850 will fit on your 77 750. But the CV carb models (80 and later) use a different head with larger port sizes for the larger carbs.

So, if you can find a 79 850 head that uses the VM carbs, you probably would rejet to the 850 specs.

If you use the later head, you'll need some sort of larger carb. The Cv carbs that match the head don't really have a big performance upgrade from the smaller carbs. OF course, you can drop $300-$1,000 for a set of smoothbores or similar for maximum performance.


The exhaust system for the 77 should fit

A couple members have done this. Do a Search and see what they did.

[jabberjoe87]

Yea, I have the vm26 carbs and they are in such good condition and i don't really need to or want to get rid of them. So a 79 850 top end is what i'm a search for.

[Nessism]

There is no reason to change the head; a '77 750 head is the same as a '79 850 head. As stated before, get an 850 cylinder and pistons and use all your other 750 parts.

[jabberjoe87]

ooooooooohhhhhhhhhhhh... ok i need to read more carefully, thanks for clearing everything up

[Big T]

ooooooooohhhhhhhhhhhh... ok i need to read more carefully, thanks for clearing everything up

Me too, I didn't know the heads are the same. But it makes sense

[nisom512]

There is no reason to change the head; a '77 750 head is the same as a '79 850 head. As stated before, get an 850 cylinder and pistons and use all your other 750 parts.

for the price you pay for just the pistons and such you could buy an 850 and be faster like I did for $500.

[Billy Ricks]

for the price you pay for just the pistons and such you could buy an 850 and be faster like I did for $500.

He'd have to allow himself to get shafted though.

[nisom512]

He'd have to allow himself to get shafted though.

oh hardy har har har. he would have less work to do in the long run on the shafty tho.

[Billy Ricks]

oh hardy har har har. he would have less work to do in the long run on the shafty tho.

Not so. I've never understood the idea that chains are high maintenance. A good quality sprocket and chain set needs minimal adjustment and lubing a chain takes very little effort.

[tkent02]

If you are looking for these parts, I have a cylinder, pistons, and most gaskets for a 1979 850, PM me.

[jabberjoe87]

I am blessed to live by Balitmore Cycle Salvage and can get just the cylinders and pistons for cheaper than old dirt. If I was gonna spend money I would just put a 1000 motor on it. I already got a nice exhaust and carbs on this guy so i'm just doin whatever to this motor. Just need enough umph to keep pullin away from my buds 81 kz750 ltd

[Lee O]

begging your pardon...

Any year 850 will fit on your 77 750.

I have to question that. I don't think "any year 850" will work. You have to clearance the upper case if you use 80 or later 850 cylinders. If you don't, you'll go through all the work and slide the 850 cylinders down until they stop about 1/4" from seating on the case. Trust me on this one.