Large Oil Leak from gear shift mechanism cover

[LastSerio87]

I have a '78 CB750 and I can't seem to figure out why once the bike gets hot it pours oil out the left rear case cover which houses the shifting mechanism and oil pump. Originally I thought the gasket was to blame, so I used black rtv oil gasket create-a-seal. That worked for just couple rides, as i was trying to adjust carb issues, then it started to pour out again... I thought maybe the housing was warped. I have a second parts engine (one with a blown cylinder due to a previous owner) so I switch housing and used a new gasket i bought off of cb750.com. It ran for about 10 min and i rode it around a parking lot, then it started leaking again. It leaks at the bottom and through the left side screws. Any suggestion and help would be greatly appreciated.

 

[dirtdigger]

Is this a sohc motor or dohc motor...the oil pump isn't under a side cover on the sohc motor but it is on the dohc but in 78 they didn't have the dohc motor yet. I need to figure out what you have for a bike before I can help much. Can you send a photo of the area? Have you cleaned the case well and check for any cracks?

 

[LastSerio87]

I clean and checked last time I had the cover off and didn't come across any cracks or visual distortions. I'll take some photo's and post them as soon as i can.. thanks

 

[motogtp]

If it is a SOHC is there any chance that one of the wiring bundles from the alternator is getting pinched when you put the cover on? On mine they run in a non-oil channel above the gasket.

 

[Retro_Weirdoz]

Curious what oil your runing in that i had someone run 5/40 syn and dripped out of every place possible it went away when he ran 10/40.

Sal