SOHC Case Mating Question

[Swaggin_Waggon]

I bought this 71 cb750 and have been doing a complete build. While mating the two engine cases it seems to be sitting not flush. I went back and double checked everything internally and it seems to be correct. Did I do it incorrectly or is this gap normal?

I don’t have pictures but the front closest to the oil filter is flush and the back has roughly a 1/4 inch gap in between the cases

 

[Swaggin_Waggon]

23/25 images align and 14/13 images are art the same time

 

[dirtdigger]

No gap is normal, they should fit perfect. If you have a gap you dont have something correct

 

[Swaggin_Waggon]

Part of the engine case was cracked so I replaced it with a 72 engine case. Everything I read showed they were compatible. Was I mistaken?

 

[dirtdigger]

yes they should fit but you dont have something lined up inside. They usually fall right together. Check dowl pins, shift forks in correctly, transmission bearing alignment clips in correct.

 

[UK K6]

I understood that due to casting tolerances, the case halves were matched in the factory. Some may interchange fine, but that's luck. If you've done everything correctly, this may be your problem. You may need the other half of the good one.

 

[dirtdigger]

Yes case haves are machined in sets and cant be mixed. I guess I just assumed the original poster replaced the as a set.....guess we will wait for more information from them....

 

[Old Paul]

The engine gasket kits changed between the 1972 and older and the 1973 and beyond. On my 1973, previous owner ran the chain through the cases and changed both. It might be the only way to go is to change out both.

 

[Swaggin_Waggon]

Thanks everyone! Turns out it was the one thing I swore it couldn’t be. The bearing retainer ring was sitting just a little too high and not flush causing the case not to go all the way down. Got it sitting correctly now.