[COOLCAT71450]

Hey y’all!
I recently purchased a 1971 CB450 and could use a little help trouble shooting an issue. I changed the oil on the bike with Honda specific 10w-40, but I made the mistake of checking the oil level while the bike was angled on its kickstand. Thus running the bike with way too much oil... Hindsight 20/20. I have since drained the oil to the correct level, but now the bike wants to stall at idle. I’m not sure if excess oil is to blame, but the bike seemed to be running fine before the oil change. The exhaust has also been smoking a bluish/ white color even when the engine stalls. I assume this is just oil burning off, but why would it continue to smoke for a couple minutes after the engine is cut? And since I haven’t touched the carbs why would it stall at low rpms only? Could the extra oil have damaged a seal/gasket?

 

[circling the drain]

Overfilling the engine a little isn't the cause of any of those problems, you're just discovering things that weren't discussed before you bought the bike. Not likely you did any damage with it being overfull, the 450 can be safely run at the top of the pressed section of the dipstick when checked on the centerstand and by just setting the dipstick in the engine (not screwing it in). Since you have one of the more complex Honda twins from that era, you should take a look at this

Important information for all DOHC 450/500T owners

Many here, including myself, have often talked about the safe approach to warm-up on a 450 or 500T with respect to oil flow to the top end. The design of the cylinder head does not allow for any residual oil to remain under the cams and followers to keep them properly lubricated until oil flow...

www.hondatwins.net

 

[COOLCAT71450]

Overfilling the engine a little isn't the cause of any of those problems, you're just discovering things that weren't discussed before you bought the bike. Not likely you did any damage with it being overfull, the 450 can be safely run at the top of the pressed section of the dipstick when checked on the centerstand and by just setting the dipstick in the engine (not screwing it in). Since you have one of the more complex Honda twins from that era, you should take a look at this

Important information for all DOHC 450/500T owners

Many here, including myself, have often talked about the safe approach to warm-up on a 450 or 500T with respect to oil flow to the top end. The design of the cylinder head does not allow for any residual oil to remain under the cams and followers to keep them properly lubricated until oil flow...

www.hondatwins.net

Thanks for the quick reply and linked thread. It’s definitely information I’ll keep in mind once the bike is running smoothly again. Hypothetically though, could too much oil damage a head gasket? I think I had read in the service manual that low compression can be a symptom of stalling at lower rpms. i don’t want to jump to any conclusions yet, but after checking compression on both sides, the left cylinder tested a bit low.