78-79 GS1000 head vs big port GS1100G head - chamber vs dome cc's?

[Chuck78]

Can anyone confirm whether the GS1100G cylinder head's combustion chamber is larger than the 78-79 GS1000 head's combustion chamber? I am contemplating building a 1000 bottom/1100G cylinders/Wiseco 1085cc 73mm pistons and using an 1100G big port head.


With the 1100G's bigger bore and 1.2mm longer stroke, Suzuki would have had to design either a larger combustion chamber and/or smaller piston domes into the 1074cc GS1100G.


Can anyone confirm if it was one or the other, or both? Or even better yet, has anyone calculated how much of a drop in compression ratio is to be had when putting the 1100G head onto a 1000 64.8mm stroke vs the 66mm stroke1100G crank? Assuming that the 1100G chambers are slightly larger? If 1085 Pistons are designed for the 1000 combustion chamber, and the 1100 G chamber is bigger, there would be a slight drop in compression. Is it typical to mill the head .020"-.040" or so (& then degree the cams with slotted speockets) in order to bump it back up?

 

[Chuck78]

Also, I believe I read that the rods on the GS1100G were slightly longer than the GS1000 rods. Can anyone confirm by how much, & give any info on how one would go about running the longer rods on a GS1000. If it's just a short difference, maybe just the slightly taller deck height on the 1100 block makes up for the rod length difference. If longer, custom pistons may be required, which could be a realy trick setup, but definitely will add several hundred dollars to the build...

 

[thebrandonbeezy]

I know the 11g head has a slightly bigger chamber. I dont remember off the top of my head but a mild skimming will bring it to yhe same as the 10g

 

[Chuck78]

http://www.thegsresources.com/_forum/showthread.php?207088-66mm-stoke-for-a-2v-gs1000

To answer your question, yes it is possible to modify an 1100 crank to fit into the GS1000 2V motor. It is expensive and requires case modifications. Back when I was drag racing, I had two of these break and the damage was bad.
.....The hot set up is to use the 1000 crank with 1100 rods as they are longer and stronger, especially around the wrist pin area.....How big is your current motor ?????.......Billy

Apparently the 1100G rods (? Not 1100E 16v rods??) are an upgrade to the 1000 crank as they are longer/stronger & use bigger big end bearings than the 1000 rods. I'm just not sure of the tricks to make this happen...

 

[Chuck78]

ALSO, same thread linked/quoted above:

Is it possible to up the stroke on a gs1000 to 66mm using parts from either the gs1100 16v or the gs1100g??

my XR69 replica uses the 16v gs1100 crank, primary gear has to be moved on the crank to line up with clutch in the gs1000
this requires no case modifications
roger upperton in the uk modded the crank, from memory the web is machined to move the gear closer to the web
ozman

ALSO, other very pertinent info that I had been using to justify a GS750 based custom big bore, as Yoshi modified GS1000 heads to use GS750 cylinder head cam chain idler gears/jockey pulleys and custom longer cam chains:

Starion007[/B];1847235]
Ozman, that a great looking bike, I am curious if you had to modify the cam chain guides and slider? I read that cam chain control was a real problem for the super bikes of the day that Yoshimura built.

Thanks, Mark

running ape manual tensioner and standard guides decided not to fit the extra roller under cam cover yoshi style as most of the reason yoshi did it was because of cam chains stretching in the longer endurance races this bikes only for sprint races 4 to 6 laps mostly

ozman

 

[GregT]

No need these days to do the 750 idler sprocket mod. We're using cams probably bigger than Yosh did in roadracers and chain life is very good.
DID if you want to know...

 

[Chuck78]

Here we go, different Google search terms and a few hours pulled up these old posts above & below:

http://www.thegsresources.com/_forum/showthread.php?95210-Limits-of-GS1000-rods

My bike was also running 5.20's at about the 220 MPH for just about 5 or 6 years before the 1000 rod let go. It probably had around 500 passes on it.

After seeing how much beefier the 1100 rods were, I opted to go with them. They are slightly longer, which is desireable for a N/A motor, and required a custom copper base gasket to get the deck height right.

I had 2 1100 cranks (longer stroke) break in my motor almost back to back and decided the best set up for a N/A GS1000 motor, would be a 1000 crank with the 1100 rods and the 1100 big left end.........

I took the small end from the broken 1000 rod, drilled a hole through it and made a key fob out of it. Daily reminder to focus on not breaking parts......BadBillyB

 

[Chuck78]

Can anyone (Billy????) elaborate on this mod?
Greg, are you saying to just upgrade to a new high end DID cam chain? I recall reading the CycleWorld 11+ page Yoshimura GS1000 build article in depth and hearing how vibrations and waves in the cam chains caused them to flutter back and forth wildly and grind on the cases or something, & this was only made reliable by the 750 idler mod and a custom length cam chain that Yoshi hand polished the sides of to make them run smoother through the guides...




So I'm really leaning towards now doing the 1000 bottom with the 1100 big end mod Billy mentioned, and whichever 1100 rods (G or E?) that Billy mentioned. May as well do straight cut gear while the crank is apart.
Back cut the trans gears + heavy duty clutch hub/basket mods. 750 oil pump gears. The toughest cam chain DID offers for the 1000. Build the bottom once to be as tough as a 1000 bottom can be. Afford the top end later if I can't swing it all at the same time. I'm sure I would be more than ecstatic if I were putting down 115hp-120hp at the crank, & with great riding skills after some racing schools, could be very competitive on it. Truthfully, I'll probably be doing most of my entry into WERA racing on a Formula 500 prepped 489cc GS425. Lighter and more forgiving for a racer in the early learning curves... Cheaper to rebuild/replace as well! Still, building the GS1000 for the Rickman will spare no detail, even if it takes me 2 years to get it sorted how I want...

I'll have to inquire with Billy about this custom copper base gasket. If it's substantially thicker, maybe I can just have JE custom make a version of the wiseco 1085 piston and move the wrist pin location up the distance required toward the crown to give a zero deck with a stock 1000 base gasket and lightly milled deck

 

[GregT]

We're pulling over 10grand on the roadrace motor with stock chain guides and a manual tensioner.
DID heavy duty camchain. Some time back, Ray asked if anyone had experience with this as his favoured Tsubaki was going off the market in the US.
We've not been able to get Tsubaki in NZ for years, no probs with the good DID.
We're also using cams with around .450in lift and 260degrees or so at .050in lift - so not exactly wimpish valve springs...
Modern cam profiles are much better at avoiding bad acceleration rates in the valvetrain. Ti retainers and small under bucket shims help too.

 

[Guest]

I have a spare, unused,since being built, 66mm crank with straightcut gear and gs1100G rods etc , new big end cages modded to fit into a gs1000e bottom end. PM me if interested. www.suzukiperformancespares.co.uk

 

[sharpy]

We're pulling over 10grand on the roadrace motor with stock chain guides and a manual tensioner.
DID heavy duty camchain. Some time back, Ray asked if anyone had experience with this as his favoured Tsubaki was going off the market in the US.
We've not been able to get Tsubaki in NZ for years, no probs with the good DID.
.

The same DID part # as standard or you have a better one? thanks

 

[GregT]

The same DID part # as standard or you have a better one? thanks

I don't know, sorry, and i haven't kept any boxes they came in.
I go into my local DID agent and they take one look at me and say "heavy duty one again Greg ?" I simply nod....

I do know that DID make at least 3 grades in that size.

 

[sharpy]

I don't know, sorry, and i haven't kept any boxes they came in.
I go into my local DID agent and they take one look at me and say "heavy duty one again Greg ?" I simply nod....

I do know that DID make at least 3 grades in that size.

ok cool. ill ask my people. lol

 

[BadBillyB]

You might want to call member "nickp" at "suzuki performance spares" and get some details about the crank he has offered. He is very knowledgeable about the GS1000 and runs his own online store. He is a crew member for one of the quickest motorcycles in the world and is a GSR member.......Billy

 

[GregT]

You might want to call member "nickp" at "suzuki performance spares" and get some details about the crank he has offered. He is very knowledgeable about the GS1000 and runs his own online store. He is a crew member for one of the quickest motorcycles in the world and is a GSR member.......Billy

If the owner of the GS1000 racebike I look after was still working in the mines in West Australia, I'd be all over that offer...But now he's got a family....
The low mileage, welded from new crank we picked up locally will have to suffice...

 

[Chuck78]

I did some parts fiche digging. The 1100G and 1100G cranks use a 31mm o.d. on the crank/big end rod pin. The GS1000 (except for the '82 GS1000S & maybe 1000G's?) use 29mm.
The big end rod bearings on the 78-79 GS1000E/C/N are 29x39x20. The 1100G and 1100E use 31x39x21 bearings. So the big end bore of the rods are the same, but the 1100's take a 1mm wider bearing.
Suzuki only lists the dimensions of the 1000 crank's rod bearing thrust washers, not the 1100's, so I cannot compare.

I'm assuming to run 1100G rods on a 1000 crank, that you would need to either find a 29X39X21 bearing and thrust washers that are 0.5mm thinner than GS1000 spec, or else run the stock 1000 bearings and thrust washers, and simply mill 0.5mm offof each side of each 1100G rod.

The big ends on the crank being larger is as much motivation for me to run an 1100E modded/hybrid crank(some 1100G parts) with 1100G rods as the motivation for me to run it simply due to the longer stroke. The price tag is quite lofty, but I don't want to have to tear down the bottom again!
This also got me wondering if it's possible to take a pair of 2 cylinder gs400/425 cranks and combine them to make a GS750 stroker crank using different main bearings than either bike originally... 60mm vs 56.4 stroke I believe...


I think I'm going to have to jump on Nick's crank offer. Brute reliability and extra torque from the longer stroke...