Splitting the cases - case gasket? Gearbox troubleshooting, etc

[Chuck78]

We swapped out a lower compression original 77 GS550 engine last year for an engine with like new compression. Now the newer engine is having shifting issues, gets stuck in first sometimes. The older one would get stuck in neutral sometimes.

I'm going to rebuild the old one with an 81 GS650GZ top end to make 9.4:1 compression and 673cc's, but the gearbox issues need addressed. Any clue where to begin? Bent shift fork? I have read about some slots in the sides of the gears that are involved in shifting that get worn as well. Could it just be worn linkages?

The bigger question I have is for gaskets. I may buy a complete 650 gasket set just to get the head gasket, as they are $120-150 seperately. As far as splitting the cases, I seemed to notice the crankcase fisches don't seem to show any sort of case gasket that goes between the two halves. Am I missing something here??? Just use RTV? Or is there a gasket? I'm comparing Boulevard Suzuki and the dreaded BikeBandit, no case gasket apparently. What's the deal?

 

[Agemax]

there is no gasket between the 2 crankcase halves. you need to use mating surface sealant. not silicone sealer

 

[Baatfam]

No gasket. Use a sealant like ThreeBond 1104 or 1211, Yamabond or Hondabond

Trans: Depends what the problem is.

 

[Suzuki_Don]

Same as above, use the correct ThreeBond sealant.

Also measure the distance between the forks and their respective grooves in each gear to check they are within spec. Also check the forks are not bent.

Look for a low mileage transmission. I found one on ebay with only 9k on it and swapped the shafts and gears as a job lot.

Read the factory manual and do all the checks it suggests. Don't miss anything.

 

[Nessism]

The transmissions are very robust. More likely the problem is a bent shift shaft or the selector mechanism is at fault somehow.

ThreeBond 1194 is the stuff for the case halfs http://www.z1enterprises.com/ItemDe...n=ThreeBond+Liquid+Gasket+1194&item=TU53-0395
It replaced 1104 in Threebond's lineup. Threebond makes all the various Suzukibond/Hondabond/Yamabond/Kawabond products.

 

[Chuck78]

Good to know on the gearbox. I had read that there were some notches or something i the sides of some of the gears that get worn and cause shifting troubles, but I am not well versed as of yet with GS transmissions, so I figured I'd have to do a step by step inspection as covered in the Clymer's and Factory Service Manuals.