will a 82 gs850 top end fit a 78 gs750

[Big E]

I have a 78 750 I'm wondering if a 1982 850 top end pistons and all will fit and what work has to be done to make it happen?

[Nessism]

The archieves has lots of information on this swap so you may want to use the Advanced Search function to find the info you need. Oh and yes it will fit but the carbs are a different size. The 79 850 has the same head as your bike so you might want to keep your old one and just install the cylinder and pistons.

[Big E]

i searched some previous post, I'm just a bit confused one post stated that the cases had to be bored for the 850 jug to fit the 79 750

[tkent02]

Just a little dremeling, not a big deal.

[gssuzukixxx]

Just a little dremeling, not a big deal.

I am interested in doing this too to my '77 GS750. I understand that the '79 GS850 cylinders drop right on but the later ones have some kind of ridge on the spigots that go into the crankcase preventing them from going down all the way.

Can you describe this and what kind of dremeling is required? How can you keep grindings out of the crankcase?

Thanks
Brian

[gssuzukixxx]

Can a 750 cylinder block be bored out to accept 850 pistons?

[Coady]

I did this mod about a month ago, using 850 pistons and cylinders and keeping my 79 750 head. Worked a treat. My 750 cylinders were shot so it was cheap fix with a little more grunt being a bonus.

I don't know what year the 850 cylinders were from, but the outside cylinders hit the inside of the crankcase with about 10mm to go. I then stuffed the crank with a rag and carefully scrapped/chipped away with a wood chisel till they fit. I know this sounds dodgy but I was paranoid about any grinding stone grit getting in the crank. I managed to get most of the aluminium chunks out, but I changed my oil & filter after about 50kms and there were a few aluminium specks in the filter.

Check this thread:

http://www.thegsresources.com/_forum/showthread.php?t=163827&page=2

And yes the 750 cylinders can be bored for the 850 pistons. It would leave the sleeves only 1mm thick though. The 750 wiseco kit is close to 850cc and requires you to do just that.