Swapping 1980 850 engine into 1979 gs 850

[Guest]

Hey y?all

I?ve got a 1979 gs850 that I?m doing a full rebuild on. I?m having to swap out the engine with one from a later mode due to the fact that when I drained the oil it was holding about 2+ liters of water in the crankcase. My question is, what options would I have for carburetors since I?m sure mine won?t fit on the newer engine. It appears the newer style CV carbs are harder to come by on eBay. Are there other models that had the same carbs just with different jetting. Any aftermarket options that may be worth a look? Thanks in advance

 

[Big T]

Just tear down the top ends of both motors and swap the 79 head onto the newer engine
Problem solved. carbs, boots and air box stay the same

 

[Steve]

Yep, that would be the easiest, even though you would need to get a head gasket and a base gasket.

Carbs are not that hard to get. Although there are subtle differences besides jetting, everything from a 550 though 850 had BS32SS carbs.

.

 

[Guest]

Just tear down the top ends of both motors and swap the 79 head onto the newer engine
Problem solved. carbs, boots and air box stay the same

Honestly a little upset I didn?t think of that as a possibility, thanks for the advice. Think that?ll definitely be the easiest option

 

[Guest]

Yep, that would be the easiest, even though you would need to get a head gasket and a base gasket.

Carbs are not that hard to get. Although there are subtle differences besides jetting, everything from a 550 though 850 had BS32SS carbs.

.

good to know I?ve got options. I?ll keep an eye out for any options. If all else fails I?ll go to the head swap like Big T suggested and use my own carbs. Thanks again for the help. Definitely glad I joined this forum, I can tell I?m gonna get a lot of useful info here

 

[Grimly]

You'll have to obtain the drive shaft from the 80 bike too. The flanges on the back of the engines are different, unless you want to simply swap the flange from the 79 to the 80 engine, but that's best left undisturbed if you can.

 

[Guest]

You'll have to obtain the drive shaft from the 80 bike too. The flanges on the back of the engines are different, unless you want to simply swap the flange from the 79 to the 80 engine, but that's best left undisturbed if you can.

noted, didn?t even realize they were different. We?re they all the same after a certain year or specific years I should look for

 

[Big T]

As Steve noted, pull the cylinder block when you change the head. It's often that you disturb the base gasket when pulling the head and oil leaks occur. So, spend the $$ on the base gasket and the oval O rings.

Also, a good time to replace the valve stem seals and end half moons.

 

[Grimly]

They changed in 1980. It caught me out the first time I swapped an engine into my 79. The shaft is otherwise identical, so fits the pumpkin end fine, I think Zuk may have beefed up the flexy joint slightly and to accomodate that, the flange was different.
Even though I suggested that simply swapping the flange might be sufficient, I can't be sure the splines on the inside of the flanges are the same, so best to just swap the driveshafts over.