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gssuzukixxx
Guest
I want to put a GS850 cylinder block on my '77 GS750. If anyone has such a cylinder block with matching useable pistons that they want to get rid of please send me a PM.
Thanks
Brian
Thanks
Brian
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gssuzukixxx
Guest
Very funny Steve...but good point.
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gssuzukixxx
Guest
BTW, can anyone describe, in detail, what grinding has to be done on the spigot openings in the GS750 case to accomodate non-'79 GS850 cylinders? How do you keep metal from falling into the engine?
Thanks
Brian
Thanks
Brian
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7981GS
Guest
What grinding?
Mine, fell right in place.
Daniel
Mine, fell right in place.
Daniel
G
gssuzukixxx
Guest
What grinding?
Mine, fell right in place.
Daniel
HMM, seems I read in here somewhere that cylinders from '80 and new GS850s didn't fit without some mod to the GS750 case. What year of cylinders did you use?
Brian
7
7981GS
Guest
'81 850 into '79 750.
Currently thinking about seeing if the 1000 bits will fit in that same engine. (920 cc's?)
(It was pulled several years ago for a 1000 replacement.)
It sure would be nice to have a kick start bike again. Just for the shocked looks on faces alone! LOL!
Daniel
Currently thinking about seeing if the 1000 bits will fit in that same engine. (920 cc's?)
(It was pulled several years ago for a 1000 replacement.)
It sure would be nice to have a kick start bike again. Just for the shocked looks on faces alone! LOL!
Daniel
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gssuzukixxx
Guest
That's good news Daniel. I'm going to do it as soon as I can find the 850 parts.
Don't really know about the 1000 parts in a 750. I know the GS1000 has a longer stroke as well as bigger bore. Are you thinking of putting the 1000 crank in?
I have read on here that it is not that hard to put a whole GS1000 engine in a GS750 and in fact the GS1000 engine is lighter than the 750.
Brian
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Guest
Guest
Check out this thread: http://www.thegsresources.com/_forum/showthread.php?t=163827&page=2
My cylinders hit the inside of the cases with about 10mm to go. It was pretty close; I only had to remove a few mls to make them fit. I stuffed rags in the cases and smeared a bit of grease around to try and catch the aluminium chips. Some smaller pieces got through and showed up in the filter which I changed early (50kms) for this reason.
If I did it again I probably would pulll the sump cover and flush it through with kero.
The photo below shows what I removed. I had to do this on both sides of the outside holes of the cases.
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gssuzukixxx
Guest
Thanks Coady, that is just what I was after. Still looks pretty doable.
Also, which cams did you guys use. I understand the 850 cams are different than the 750...more low and midrange. I must say, I own a GS850 and a 750 and don't notice a huge diffence. They both have a furious rush of power above about 6000 RPM.
Brian
Also, which cams did you guys use. I understand the 850 cams are different than the 750...more low and midrange. I must say, I own a GS850 and a 750 and don't notice a huge diffence. They both have a furious rush of power above about 6000 RPM.
Brian
7
7981GS
Guest
Not at all what I was thinking.
I was thinking of building a short stoke large bore version of the GS engine.
High revving big bore.
Something that suzuki never did kind of thing, just to see if it could be done.
Not sure which cylinder head to use yet or stock/ after market pistons.
Lot's of possibilities.
Perhaps RapidRay knows if it can be done?
On the 1100 into a 750 frame... BTDT.
Daniel
The cylinder stud pattern is the same from GS750, 850, 1000,& 1100 8 valve models. The wrist pins are 16mm for 750/850 and 18mm for 1000/1100. The 750/850 use a cam chain idler between the cams, the 1000/1100 doesn't. The 750/850 use 36mm & 30mm valves. The 1000/1100 use 38mm & 32mm valves.
Anything is possible if you want it bad enough. I have a 1025cc GS750 motor. Stock stroke with a 76mm bore. Uses wiseco KZ1000 pistons that are 6mm over for the KZ, and 11mm over for the GS750. Wrist pins are 17mm so the stock GS750 rods are bored and honed 1mm over. Custom base and head gaskets. The head has 37.5mm intake valves and 31mm exhaust valves. Dar
Anything is possible if you want it bad enough. I have a 1025cc GS750 motor. Stock stroke with a 76mm bore. Uses wiseco KZ1000 pistons that are 6mm over for the KZ, and 11mm over for the GS750. Wrist pins are 17mm so the stock GS750 rods are bored and honed 1mm over. Custom base and head gaskets. The head has 37.5mm intake valves and 31mm exhaust valves. Dar
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7981GS
Guest
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Guest
Guest
I just used my GS750 head and cams. Top end rush you mentioned seems similiar to before, but low end/mid range grunt has definitely picked up. Having said that, my clutch started slipping shortly after the rebuild at around 6k in 3rd gear so I guess there is more HP there; I put new springs in and fixed that. I'm pretty happy with the result but the stock 750 was pretty good already.
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Guest
Guest
It is still a work in progress. I have started it and it sounds great. It is in a drag bike. I used 29mm smoothbores. .429" lift cams with shim under buckets. With 13:1 compression I use a remote starter. It has a welded crank, pro cut transmission, and a reinforced clutch basket.
The previous 1000cc motor had 75mm pistons that were made for a GS750 with the correct wrist pin size. A home ported head with stock valves, and .395" lift cams. It ran well but it had poor ring seal. The previous owner of the pistons ran stock cams with high compression and detonated them enough that the ring land was partially collapsed and would not let the rings seal.
The previous 1000cc motor had 75mm pistons that were made for a GS750 with the correct wrist pin size. A home ported head with stock valves, and .395" lift cams. It ran well but it had poor ring seal. The previous owner of the pistons ran stock cams with high compression and detonated them enough that the ring land was partially collapsed and would not let the rings seal.
7
7981GS
Guest
So, you are using the early 750/850 cylinder head with the smaller combustion chambers?
I did that on one of my 1000's with over-sized valves to help bump the C/R.
Daniel
I did that on one of my 1000's with over-sized valves to help bump the C/R.
Daniel
Yes the early 750 head because that closely resembles the combustion chamber of the KZ1000 engine. Same size valves too and that is why I used KZ aftermarket Wiseco pistons. The latest head that I have yet to install has 1.5mm oversize intake valves and 1mm oversize exhaust valves (37.5 & 31) along with a port job from Babor Performance Motors.
If I wanted more compression on a GS1000 motor I would just mill the head. The stock valves on the GS1000 are 2mm bigger on both sides than the 750/850.
If I wanted more compression on a GS1000 motor I would just mill the head. The stock valves on the GS1000 are 2mm bigger on both sides than the 750/850.
7
7981GS
Guest
Custom made 38mm Intake valve and GS1000 30mm exhaust valve in a '81 850 head.
When the cam chain broke @ about 3,000 rpm, I immediately hit the kill switch and pulled in the clutch.
Apparently, the intake and exhaust valves had a dispute as to just who belonged in the chamber at the same time:
For comparison, '81 GS1100GL head:
The camera lens does not show clearly that the 850 combustion chamber is 65 mm in Dia. and the 1100 combustion chamber is 70mm in Dia.:
(fish-eye lens.)
I forgot just how many cc's difference there is between the two.
The valve reliefs in the 1000 Wiseco pistons were cut 4 mm over intake and exhaust and .040 deeper to give a little breathing room with the .392/.392 camshafts.
When the chain breaks, GAME OVER.
Daniel
When the cam chain broke @ about 3,000 rpm, I immediately hit the kill switch and pulled in the clutch.
Apparently, the intake and exhaust valves had a dispute as to just who belonged in the chamber at the same time:
For comparison, '81 GS1100GL head:
The camera lens does not show clearly that the 850 combustion chamber is 65 mm in Dia. and the 1100 combustion chamber is 70mm in Dia.:
(fish-eye lens.)
I forgot just how many cc's difference there is between the two.
The valve reliefs in the 1000 Wiseco pistons were cut 4 mm over intake and exhaust and .040 deeper to give a little breathing room with the .392/.392 camshafts.
When the chain breaks, GAME OVER.
Daniel
When you install larger valves on these 2 valve heads you must maintain a minimum of .185" distance between the valves when they are on the seats. If necesary you have to sink them deeper. This worked out for me because The KZ oversize valves are shorter than the GS750 valves, and I needed to sink them to get in the shim range.
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