Oil leak from front of 1980 cb750 bobber

[rmilheim90]

Hey everyone!

I'm new to these forums so allow me to introduce myself. I'm a fairly new owner of a 1980 Honda cb750 bobber and i love it thus far. It's my first carbuerated engine so there is a learning curve for me maintenance wise. Anyway, i have the following issue (i think) and am reaching out to you guys. (pictures below)

i noticed the other day while riding a lil bit of smoke coming from my exhaust on the front of the engine. After looking closer i noticed oil was dripping off this "port" or "valve" ... to be honest, idk what the hell it is and Google hasn't been any help. Can someone give me some advice on what it is? if it needs fixing I'd like to do so before Thunder Beach this coming weekend.


Thanks guys! View attachment 6527

 

[Jdlong27]

That "valve" you speak of should have a bolt and nut in it. That is your front cam Chaim tensioner adjustment. Do a search for "adjust can chain dohc" for a video description. Is there anything in the hole? (The top most threaded one at 11 o'clock , not the blanking one straight forward) when that (non-existent) bolt and nut are loosened, the cam chain tightens, and then it's locked back down to keep it in place.

 

[rmilheim90]

Thanks JD .. is it dangerous to have it missing from the engine? I plan on fixing it, especially to stop the leak, but I have to ride it home from work today haha.

 

[Jdlong27]

That I couldn't tell you. Sorry. Make sure you check the oil level before you leave though.

Best I can tell is that with it removed would be the same as leaving it loose. Which, in turn, would try and tighten the cam chain constantly possibly wearing something in that internal mechanism out. The guides are a weak point on these motors already. I definitely would get it fixed without riding more than you have too, just to be on the safe side. Someone else may be able to chime in on the potential damage beyond leaking oil.

 

[amc49]

Left loose allows the tensioner to bang around based on chain slapping it. If tensioner old and rubber cracked it will begin to come apart. Bolt hole may well be stripped and common, you can't apply much torque there even when new and many people tear the hole up. Helicoil the usual fix there.