GS1000 to 1100G motor conversion.

[limeex2]

With Chuck78 starting threads on the 1000/1100 conversion, I figured its a good time to ask for information instead of stealing the thread like I usually do. irate: I will be doing this mod on my next build. No crazy mods, just stock parts for stock parts. I have a 78 bone stock GS1000. It needed the usual, points, carb rebuild, fork seals, chain and sprockets, head and valve covers both leaked oil. A member was offering a 1100G top end that included carbs and an ignition. So I figured for only a few more $$ in parts I would get modern carbs and ignition and another 100cc.

Question is, since I'm terrible at searching for links, and find it fun to share opinions and ideas, can someone post a link on what modifications and parts are needed to make this upgrade work? I believe there is some machining that needs to be performed. Is there more to it? I want a stock motor with no internal mods other than the 1100G top end. I have many plans for this one...

 

[sharpy]

get a whole 1100 wreck . u have everything u need then and sell the left overs

 

[Nessism]

Found a thread for you that should help...http://www.thegsresources.com/_foru...0G-Cylinder-amp-Mikuni-RS34&highlight=gs1000g

 

[limeex2]

Found a thread for you that should help...http://www.thegsresources.com/_foru...0G-Cylinder-amp-Mikuni-RS34&highlight=gs1000g

Thank you, lots of info and a good read!

 

[Chuck78]

Basically from what I have gathered on here, the 1100G has a 1.2mm longer stroke which equates to 0.6mm more piston travel upwards (&equal additional travel downward). Same length rods. Same piston compression height pin to crown.

What this means is that the 1100G runs a deck height that is approximately 0.60mm taller to make up for the additional stroke. So you just want to run the GS1000 base gasket which is .020" (0.5mm) vs the .039" (1.0mm) 1100G base gasket. I think this requires slight trimming of the sleeve holes in the gasket.
This leaves you with only 0.1mm difference in deck height vs the factory deck height with the 1000 crank and 1000 block.
I think I read that Suzuki factory setups generally left the piston down in the hole about .020" (if I recall correctly - ?, always need to torque cylinder properly without head to measure piston down in hole deck height yourself). If that's the case, decking the block .1mm would get you factory deck height, but you really want close to a zero deck height to optimize the quench height and anti-detonation tendencies. So milling 0.40mm - 0.60mm or so off the deck surface based on your exact setup should yield you a zero deck height (piston crown edge even with top of block) to optimize your compression ratio and efficiency/resistance to detonation (pre-ignition).

Also the chambers on the 1100G head are slightly larger, so milling the head a slight bit will help bring that compression ratio back up to stock. A zero deck and a lightly milled head should put you back to good stock-is compression ratio. Getting them milled in general is always going to give you the best sealing surface for the most critical sealing gaskets on the whole engine, so this is a great idea regardless.

Your cam timing will be slightly advanced with milling the head & going from factory deck height to zero deck height, but not a drastic amount. If it does anything it will give you more midrange torque.

 

[Chuck78]

I ended up taking Nicks offer on that 1100E crank and 1100G rods modified to fit the 1000 crankcase. 1105cc and slightly higher compression.

 

[850 Combat]

I know that the crank shaft diameter on the left side is larger on an 1100G than on a 1000G. I had a starter clutch go out on my 1000G. When I went to replace it, I discovered that the starter clutch would not fit. That's when I found out a PO had installed a 1983 1100G engine. I did not know hat there was a stroke difference. I've got a couple 1000Gs stashed in various locations. That is the peppiest one, for sure, but not by much.

 

[John Kat]

I did the modification on my GS 1000.
The block was shaved by .9 mm but 1 mm would have been OK I believe.
See the pictures.
http://www.thegsresources.com/_foru...e-to-GS-1100-G-cylinder-block-head&highlight=