85 gs700 jug on 83gs 750 crankcase

[helmutholderbenz]

Hi my name is Helmut I am new to the forum but not new to the GS. I am currently rebuilding my old 83 gs 750e. I have the weisco 816 kit can I use a 85 gs700 jug since I will be boring it anyway? I sure would appriciate any ones feedback! Thanks Helmut

 

[ShadowFocus603]

Do you have the jug to compare to what is on there now? If not, try to find pics to compare. The fiddly bit I'd imagine will be bore spacing, stud positioning, and whether or not the head will even bolt on. If it were me, I'd just grab a set of jugs possibly on ebay (don't know your location you may have better alternative) and just bore them. Removes the question of fitment completely.

 

[helmutholderbenz]

Do you have the jug to compare to what is on there now? If not, try to find pics to compare. The fiddly bit I'd imagine will be bore spacing, stud positioning, and whether or not the head will even bolt on. If it were me, I'd just grab a set of jugs possibly on ebay (don't know your location you may have better alternative) and just bore them. Removes the question of fitment completely.

Both motors have 67mm bores

 

[Nessism]

Cylinder part number is different.

 

[jetta90]

There is an 1983 GS 750 parts motor in my garage that I could dismantle if you need the cylinders.

 

[Guest]

Both motors have 67mm bores

Only the crankshaft and connecting rods were different on the 700. Same pistons on both. I'd use it.

 

[helmutholderbenz]

I like your answer Kingofvenus, I'm thinking the same thing, only problem is when I look at the diagrams the cylinder and base gasket# do not match. Also, there seems to be three kinds of cylinder studs on the 700 and only two on the 750. Has anyone ever done this before and knows for sure if it will work or not? I have my 750 motor in my bike and I picked up this 700 jug cheep($10) The bike runs, I am just trying to get a jump on things so maybe I can tackle this project in a weekend instead of a week. Hey, Thanks for your offer jetta90

 

[blowerbike]

may end up with to much positive deck height..

to measure is to know...

 

[helmutholderbenz]

If I have to break my motor down to compare the two I will just use my 750 jug, sure was hoping someone had done this or at least tried it before

 

[Grimly]

If it's the same pistons and the 750 is a longer stroke; if you use the 700 barrels on the long-stroke crank, you'll have to be very careful about measuring piston/valve clearance - you might even smack the pistons off the head. Much crunchiness and burning of money.

 

[helmutholderbenz]

but wouldn't it be made up in the crankshaft?

 

[helmutholderbenz]

I guess Blowerbike said it best, To measure is to know!

 

[Grimly]

I guess Blowerbike said it best, To measure is to know!

That's about the size of it. I'd wondered about rod length and parts-bin engineering, but got bogged down in speculative drivel.