Internal differences between gx160 and gx200?

[Smerft85]

So I've got a gx200 "clone" with what I hope to be at least a good crank, as well as a gx160 "clone" that runs very well, but has the wrong shaft. I'm sure things such as valves, piston and bore are larger in the gx200, but is there any difference in the crank or rod? I'd like to use the crank from the gx200 in the gx160 if it's possible, anyone done it?

 

[itsid]

it's exactly the other way around..
same bore more stroke...

(gx160 is 68x45mm bore stroke (163cc) and gx200 is 68x54mm bore stroke (196cc) )

So no, the crank is the main difference.

IDK if the GX160 case has enough of a cylinderwall to allow the full GX200 stroke
(essentially rendering it a gx200)
worth to test, afaik everything else about the crank's critical dimensions is identical...

the GX160 head is the "better" of the two actually..
they have same size valves (24.5 and 27.5 mm) and more compression
(especially older e14 heads) for identical fill rates and a bigger oomph
according to the manual I'm looking at the gx160 also has a 5° advanced spark
(25° vs 20° BTDC)
So it also likes to rev up a bit easier

'sid

[EDIT]
shoot the gx200 exhaust sits 4mm higher suggesting a longer cylinder...
chances are it won't fit then

 

[Flyinhillbilly]

One other difference is that the lifters are a little shorter and lighter than the 200, which means more rpm before valve float. I’m pretty fond of a ported 160 head, compression makes woopow, and that’s the dragon that most of us are chasing.
My vote is to mock up the 200 crank in the 160 because I made it work a few years ago, but I can’t remember the piston/rod combo I used with it. Try mixing and matching and see what you get. Mine ended up slightly above deck height, so it was a snap to get the quench area right.
If you can get zero deck, or close to it with 160 lifters, and a ported 160 head, it makes a pretty stout little motor. Mine would go 54mph on my doodlebug with no performance parts at all, just mixed and matched home modified stuff.

 

[Smerft85]

Sounds like some tinkering is in my near future, only thing I saw online suggesting they would be compatible was a stroker crank listed for both models, maybe that's what you did in some way?

 

[Flyinhillbilly]

It was s stock stroke gx200 crank, I just wish I could remember what combination of rod and piston I used. I know it was the 160 piston because it was a flat top, and I want to say that I used the 160 rod, but I would t swear to it.

 

[65ShelbyClone]

The GX140, 160, and 200 all use the same connecting rod.