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750 to 850

  • Thread starter Thread starter Stormstyles
  • Start date Start date
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Stormstyles

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Will a 850 jug fit a 750 lower end? I have an 850 thats in good condition but shaft drive and my bike is a later 70s 750 that has a good lower end but the top end fins a few broke places. It was just a thought. Any help would be great.
 
You need the pistions from the 850 too. And you'll need to likely get new rings for them. A 79 850 jugs will drop right onto the 8v (pre 1980) 750 motor, but a 80 and up set of jugs will require a bit of grinding of the 750 cases to get them to fit right. Otherwise, from what ive read, its a bolt up swap.
 
Ok do you know where i Might be able to find the literature that you read. Plus Which cams would be best for this swap. The 750? Ok Also where is a good place to buy parts for these things like the rings and gaskets?
 
So, this only works with the 8v motors?

Might be fun to do to the T...
 
Oh is this a significant increase in HP and torque or not. Just wanting to know for the long term. Seeing this thing will take forever to build
 
It will bump up your BHP and torque and is worth doing - better value in my book than going the Wiseco route. 750 cams will give you more top end, 850 cams will be a bit better at the bottom.
 
You have to use the 750 cam sprockets, do away with the 850 idler sprocket
 
hampshirehog said:
It will bump up your BHP and torque and is worth doing - better value in my book than going the Wiseco route. 750 cams will give you more top end, 850 cams will be a bit better at the bottom.
Click to expand...
Id have to double check this info. I know that at SOME POINT they re-timed the 850 cams for more bottom end, but I dont know WHEN (what model/year) they did this for sure. It is my understanding that the cam timing of the 79 850 was the same as the 750. All top end. I could be wrong however. The part numbers are the same for the heads, and sprockets.
 
Cafe is right about the different cam timing, not sure how much difference it makes in the real world though.
 
Would anybody be interesed in doing this swap for me? When it comes to suzuki's I am kinda out to lunch. I can do this but with what time is my problem LOL
 
First, where are you located. Second, Do you have the necessary 850 parts to do it with? Thirdly, are you paying to have it done??
 
I am located in Knoxville tn. I have a complete 850 motor with no carbs and a complete 750 with carbs that I fired once. I will have to get the gaskets and any other necessary parts once its apart. I will Pay for it too LOL I dont expect anything for free.
 
TheCafeKid said:
Id have to double check this info. I know that at SOME POINT they re-timed the 850 cams for more bottom end, but I dont know WHEN (what model/year) they did this for sure. It is my understanding that the cam timing of the 79 850 was the same as the 750. All top end. I could be wrong however. The part numbers are the same for the heads, and sprockets.
Click to expand...

The 79' 850's cams were the same grind as the 79' GS1000. I believe that the timing was changed on later 850's by advancing the inlet opening.

I wouldn't consider the stock 850's as having all top end though. But, they certainly don't run out of puff until past the red line either, even with the airbox still attached!
 
hampshirehog said:
And you can pick what cams you like - 850 are a bit 'softer' than the 750 - they'll both fit.
Click to expand...

Stormstyles said:
Plus Which cams would be best for this swap.
Click to expand...

TheCafeKid said:
Id have to double check this info. I know that at SOME POINT they re-timed the 850 cams for more bottom end, but I dont know WHEN (what model/year) they did this for sure.
Click to expand...
They did this for the 1980 model year.


Nessism said:
Cafe is right about the different cam timing, not sure how much difference it makes in the real world though.
Click to expand...
I would have to ride two bikes back-to-back, but it should have better low-end response with the advanced intake timing.
Since most of our riding is in the lower half of the rpm range, it would probably make more sense.


49er said:
The 79' 850's cams were the same grind as the 79' GS1000. I believe that the timing was changed on later 850's by advancing the inlet opening.
Click to expand...
Yep. I don't have the exact numbers here, but the intake timing was advanced 10 degrees for opening and closing.

.
 
So is the bore and stroke the same Then? I would think they were different!
 
I do not have numbers in front of me, but based on the responses above, I would say that the bore is definitely bigger (hence the need to change the pistons to match the 850 cylinders), but the stroke would be the same (because you are still using the same crank).

.
 
So would the increased compression (10:25) help out? I have an 850, to swap to my 750, just wondering about the compression and the cooling.
tucker
 
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