'80 850 head on a '78 750 engine

[Anonymous]

Will this swap work?? Isn't this considered kind of an upgrade for the 750??I'm going to turbocharge engine possibly? Would this swap be benificial?? Thanks guys. OH- Jake I'm racing my brothers heavily modified Bandit 1200 this week. I might post times if I think about it. Also, will a 86-92 gsxr 750 head fit this '78 750 engine??

 

[Mark Harrop]

Why just the head? Why not cylinders/pistons as well. I'm pretty sure it's a straight swap. Might as well get some extra cc's.

As for the Gixxer head, the closest thing I've seen is a gixxer 1100 head on a 16v GS 1100 motor over at Bertaut racing. Anything can be swapped if you massage it enough.

Post the results of the Bandit race will ya? I'm curious..... :-k

 

[humhead]

The head swap will work. The cylinders are just a little too big ( I tried an 850 cylinder block on the top half of a 750 case & it sticks about 1/2" before the bottom of the block contacts the case.) There's enough meat in the 750 cylinder walls to bore the engine out to 850cc. A GSXR 750 head will not fit the 2 valve engine. You might want to try swapping the entire motor out for a bigger/ newer one. Others have used 2 Valve 1000s & 4 valve 1100s

Terry

 

[Anonymous]

Hey thanks guys.I thought the head swap would work, and I was not sure about the gixer head at all. I am in the process of getting an 1166cc motor but would like to turbo the small one in the mean time. But i'm not 100%. Would the 850 head be considered an upgrade in breathing for the 750???Need to know quick.Yes I will post the times and results after Wed. night at the track. The Bandit does not yet have a aftermarket ext. swingarm, so I will attempt to keep it on the ground. It's way front end light!! :lol:

 

[Pete's GS]

I don't believe the 850 would be considered an upgrade to the 750 head since I believe they're exactly the same in terms of valve size, port length, compression ratio, etc. The strokes are the same (56.4mm). Perhaps the 850 combustion chamber is slightly larger to accommodate the slightly wider bore (4mm, 69). The 850 was just a bored out 750 that also got about 50 pounds heavier

 

[humhead]

I don't believe the 850 would be considered an upgrade to the 750 head since I believe they're exactly the same in terms of valve size, port length, compression ratio, etc. The strokes are the same (56.4mm). Perhaps the 850 combustion chamber is slightly larger to accommodate the slightly wider bore (4mm, 69). The 850 was just a bored out 750 that also got about 50 pounds heavier

There is one key difference. The 1980 850 head has revised intake ports. The length may be the same, but changes were made to allow the use of BS32 carbs. If you add an 850 piston kit, you have the power of an 850 & the weight of a 750

Terry

 

[Anonymous]

Thank you guys.I really am greatfull for your input. I too had heard that there was something different or better about the '80 850 hea d vs my '78 750 head along with a piston kit. That might actually work pretty good with a turbo, and some juice!!!! :lol: :lol:

 

[Anonymous]

Bandit times from wed. night

Bandit times from wed. night

well mark, as I predicted this bike was real hard to 60'. I was in the 1.80-1.84 range almost all night. Wheel up in 2nd,wheel up in 3rd,and a 6" popper in 4th. 11.60 most all night. This bike needs an air shifter and an arm REAL BAD!!! But I managed to take it all the way to the final round.Where I finally got it all together ; 1.6 60' and then broke out by .08 sec. After letting off throttle 3-4 bike lengths before traps.Lets see; 11.48 @ 116.55. Does that MPH tell you how soon I got out of it!!! I went 11.56 earlier and had a 121.36 trap speed.Well, gotta go,L8R dudes.I guess runner up aint so bad on a borrowed bike!!