Oil recommendation 1971 Honda CB450

[Chris_H]

I rebuilt this old Honda CB450 a couple years ago and haven't found a oil that works well yet, Im hoping you guys can point me in the right direction.

The only important mod on the bike is I have ditched the centrifugal oil filter on the end of the crank with a modern aftermarket paper cartridge filter setup. The one other thing worth mentioning is these bikes like to wipe out camshafts and followers which are getting increasingly difficult to find.

I have tried both Rotella T 15w-40 and T6 5w-40 they work good when the bike is cooler no noises and the clutch and shifting is smooth. Once things get hot the clutch gets grabby and the shifting gets notchy and neutral gets hard if not impossible to find. I also start to hear a little top end noise.

So im looking on both grade recommendations and specific oil recommendations. Any and all help is greatly appreciated

 

[Bandito440]

Try a motorcycle-specific 20w-50. Mobil 1 and Valvoline are usually easy to find. I'd probably try the M1 first.

 

[bpracer]

Go to your local Honda dealer and get Honda GN4 20-50 and your problems will go away. Not kidding.

 

[GreeCguy]

Why did you get rid of the centrifugal oil filter?

 

[beanoil]

I'd try Havoline 20w50 first. If you feel the need for a MC specific oil, Brad-Penn V2 20w50 is a fine syn blend, and reasonably priced.

 

[danthaman1980]

Use a 20W-50 motorcycle oil. My personal favorite is Mobil 1 V-Twin 20W-50, but I also had good luck with Valvoline's 20W-50 motorcycle oil.

 

[BigCahuna]

I would try Valvoline mc oil either 10/40 as thats what's called for or their 20/50 wt. But first I would try adjusting the clutch. The oils your using should work fine in your application. If you happen to have a warped clutch plate that can cause the problem your having, but I would try adjusting first.,,

 

[Cujet]

Air cooled bikes generally do well with the heavier viscosities. Any of the above suggestions will work.

But, it sure sounds like you have mechanical issues too. A dragging clutch will cause the problems you describe and no oil will fix that. Remember that many period Honda's had insufficient clutch pull when parts were worn. The clutch actuation system is critical on such bikes. So, not only can warped clutch components cause this issue, but also a stretchy cable, a worn or improper lever, and more likely, worn actuation linkage in the engine.

Same goes for noise in the top end. Honda's are typically mechanically quiet. So, there is additional clearance somewhere.

 

[SOHCman]

I would love to see pics and a write up on your filter mod! Rebuilding a cb350 with centrifugal filter and would prefer a spin on solution.

I agree, the rotellas are 10x better oils than they had in the 70s, must be something mechanical? Maybe add a oil cooler to your external filter setup since half the work is done?!?