85 GS700 Teardown

[Anonymous]

Here is my issue. I have an 85 GS 700 with a top end that is shot
My cylinder readings are 40,80,0 120 with leakdown on 2 of the cylinders before they stopped and said no point in going further.
Here is my issue. I have never torn this apart and done something like this. I have the complete seal kit for it, and I can buy new rings if that is what I will need.
I also have a complete GS750 engine( 83 model) with a good top end, without the complete transmission parts.
What do I need to do, to make one good motor out of this.
I have heard varying things.
What pistons should I use, what jug, and what parts from each engine should I combine to make one good daily rider, nothing fancy
If anyone could help me I would appreciate it. I am in the Detroit MI area if anyone wants to help, lol
Thanks again
JB

[Big T]

If memory serves me correctly, the 700 and 750 engine are identical except for the bore (pistions, rings, cylinders)

So you should be able to put the 750 top end on the 700.

If it were my project, I'd tear the 700 down, split the cases, replace the cam chain and guides,put in the 750 crank and top end.

Or, put the trans into the 750 after splitting the cases.

I'd take both apart and see how they look inside before making the decision

[luc8421]

Don't mean to bust your bubble Big T, but there's some more differences than just the bore.

Classicrentals, you've got the perfect set up. to compensate for the decrease in engine size for the '83 750 (and '84 if you live in canada) Suzuki made the '85 700 with a more aggressive cam profile, making them almost idenical in power.

The best thing to do would be to put the 750 lower end in, using the 700 top end, so you'll have the size of the 750, with the cams of the 700.

If you did this, you'd be using the 750's pistons, which hopefully will solve your compression problem. hope this helps.

[moto_dan]

You can mix and match most parts between the two. The difference in displacement is with the stroke... the bore/pistons are the same. If you know the 750 engine is good except for the transmission then I would use the transmission from the 700 along with the 700 cams as previously susggested. BTW I'm running a 700 transmission in my 750 engine after I thrashed the 700's top end(loose rocker arm nut) so I know it works.

Note: For others who may be reading this post please keep in mind we're talking about interchangability between the '83(84 Can) 750 and the US only '85 700. :?

[Anonymous]

to get it right

I need to use
The 700 Cams
The 750 pistons and rings?
which rods?
Can I just use the 700 case and everything else, just add what from the 750 to fix my compression issue
If you list it out, I will do it. I got confused with the three different posts, but I definetly appreciate the help, and guidance
Thanks again for any help you can offer

[Billy Ricks]

Use the 750 rods and crank to pick up 50cc. The 750 rods are shorter than the 700 and the 750 crank has a longer throw.

[oldschoolGS]

The 700cc pistons are domed (to make up the compression loss from being destroked 50cc) and will give you 10.25-1 compression when used with the 750 crank and rods. Nice simple mod to boost compression and power- it will still run fine on pump gas also.

Good Luck, Ed.

1983 GS750ED

[Anonymous]

Any further needs

Should I have the cylinders honed out, and new rings put in, should that fix my compression problems.
Will I have carb issues after doing this change? or no
I sooo want to get this thing back on the road. What all should I do since I will have it torn open?