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1100GZ Shafty rebuild

  • Thread starter Thread starter 82gs1100
  • Start date Start date
8

82gs1100

Guest
:-kI hope more people will see this post.
I'm rebuilding a GS1100GZ shaft drive motor and need some advice on how much power the shaft drive can handle. This motor can be built with to much power so i don't want to blow up my drive train.
originally i was going to
have a $995 head job. now ill go with a $500 head job
110 grind cams. now i think i should stay stock
I need to find pistons. I can find part #s put not the size of the piston or rings
i will be using a Dyna 2000 ignition w/ coils because i want a rev limiter and the price of a rev limiter and Dyna s is more.
i will be using Mikuni 34mm RS carbs
The transmission will be under cut.
K&N pods
V&H 4 into 1 if they still make them
all this from what iv herd on here will grenade my drive train.

Has any1 on here rebuilt a shafty?
How much power and what did u do to get that power?
thanks
 
82gs1100 said:
:-kI hope more people will see this post.
I'm rebuilding a GS1100GZ shaft drive motor and need some advice on how much power the shaft drive can handle. This motor can be built with to much power so i don't want to blow up my drive train.
originally i was going to
have a $995 head job. now ill go with a $500 head job
110 grind cams. now i think i should stay stock
I need to find pistons. I can find part #s put not the size of the piston or rings
i will be using a Dyna 2000 ignition w/ coils because i want a rev limiter and the price of a rev limiter and Dyna s is more.
i will be using Mikuni 34mm RS carbs
The transmission will be under cut.
K&N pods
V&H 4 into 1 if they still make them
all this from what iv herd on here will grenade my drive train.

Has any1 on here rebuilt a shafty?
How much power and what did u do to get that power?
thanks
Click to expand...

I haven't heard of anyone radically tuning this model. The weakest part in the later model G's drive train appears to be the secondary drive assy.
Some members have reported failures and one has detailed a sucessful repair to the bevel gear spigot.

The cheapest significant horsepower increases are gained by raising the capacity and the CR. Next is fitting a decent 4-1 pipe. Don't fit pods unless you plan on racing this bike. All you'll achieve is less bottom end torque and heaps of agro trying to get the carbs jetted correctly.

I have an 1100G project for future modification. My plan is to fit 3 mm O/S custon pistons at 11-1 CR. A set of Keihin CR31's are put aside for this project. I plan to still run an airbox with these carbs.

Planning on running '79 GS1000 cams (same grind as the '79 850's). These profiles with slide carbs produce an exellent range of torque.

The only head mods will be cleaning and blue printing ports and valve pockets.

A programable electronic ignition is a must for achieving the best possible torque.
 
120 to 130 HP should be ok as long as you aren't drag racing it or doing burnouts or revving it & dropping the clutch. Ray.
 
130hp sounds good
ill keep the box.
i wont be dragracing it or any thing i just want it to be a little more fun coming out of the corners and pulling up next to my brother and his friends then smoking them.
well the bike could do that stock but
Now i just need to find pistions. I see the oem ones on flatout but i dont know what size they are.
i dont think i want to spend $700 on custom pistions
 
82gs1100 said:
130hp sounds good
ill keep the box.
i dont think i want to spend $700 on custom pistions
Click to expand...

How badly do you want to blow your brother and his friends into the weeds?
If you want 130 hp, you will need to run higher CR pistons and bigger capacity than the stock 1 mm O/S ones at 8.8-1 CR.

You could raise the CR with the stock overbores by milling some Ali off the head, but you will reduce the cooling efficiency, change the squish area in the chanber and alter the cam timing significantly. Slotted camshaft sprockets can fix this though.

The ideal shape and size of the squish area is extemely important.

By the time you do the milling, you may as well have the real thing. You will have something special if you go custom. The piston crowns will also be designed to safely take the extra cylinder pressures and heat that will be generated.
 
the motor machine work is being done by Fast By Gast. i talked to
Paul Gast and i think he said .020 off the head. i have to find pistons. i wanted to go 3mm over 1166cc
how much would custom pistons be :-k
i want to run on 93 octane so 10.5:1 or something like that:-k
 
I used to work at CP Pistons & am still sponsored by them. I can get you CUSTOM made pistons to your specs for $650.00. It would include pistons, pins, rings, & circlips. Let me know if you want to do something. Ray.
 
ya
i would need 4 3mm over for a gs1100gz
let me call Paul Gast or do u know if the 8v block can be bored 3mm over.
thanks i could send the money august 14th. i need to send some money to him 1st
i want to run pump gas and ill just have him take enough to straiten the head
 
You can probably get 110 BHP with only minor mods on that bike though, and from a guy with maybe 96 or 97 on a 1000G I can tell you, that's plenty to keep you on your toes.
 
I have heard that if racing, a built up GS 1000 can twist the crank since its a built up crank with roller bearings rather than a single piece crank with babbit shell bearings. I'm pretty sure the 1100 is a very similar if not the same bottom end. If you have it all apart and know someone who welds, I would have the crank balanced and welded and checked/adjusted for balance again. The last thing you want to do is throw a couple thousand dollars into an engine build and then twist the crank pins and rack your bearing seats/crack the block when you really get on it.
 
bucketsofgs1000 said:
I have heard that if racing, a built up GS 1000 can twist the crank since its a built up crank with roller bearings rather than a single piece crank with babbit shell bearings. I'm pretty sure the 1100 is a very similar if not the same bottom end. If you have it all apart and know someone who welds, I would have the crank balanced and welded and checked/adjusted for balance again. The last thing you want to do is throw a couple thousand dollars into an engine build and then twist the crank pins and rack your bearing seats/crack the block when you really get on it.
Click to expand...

Yeah, there is a point (that's below probably 130 bhp) Where you'd want to have the crank welded I think. You can build this bikes up quite a bit without worrying about it, but the roller bearings make it pretty bulletproof... to a point. I think 130 is probably past there. Just from my discussions and readings on these bikes.
 
You DEFINITELY need to have the crank checked for straightness, indexed & welded at the MINIMUM! Ray.
 
they allready checked the crank its perfact they said. Paul also said it wouldn't be nessasary to weld the crank.
im going to talk to him tues day if hes at the shop and ill ask him.
im going to do what ever i need to to a 130hp motor
i just hope we can keep it at 130hp.
i think what im having done to it mite go over
custom 1166 kit
$500 head job Paul said it would give me a 15% hp increase maby 14hp dose that sound right
118 grind web cams
compression 10.0:1 maby(i want to run on pump gas)
34mm mikuni rs carbs
dyna 2000 ignition
v&h 4into 1
what do you think
 
$50 to weld the crank arp charges $89.
Paul said he sends them out to be welded. probly cost more
ill get it welded
 
Hey, that 100 dollars is good money well spent!


An engine is only as good as its weakest link.

I always wondered if you could fit a 16V head onto an 8v engine. TSCC baby. Maybe the cylinders would have to go with the head like converting an F to a K upper configuration on a CB750.

I would think a shaft drive would hold up to a 130 as long as you roll onto the power. Of course you could just buy an FJR1300.
 
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