Engine Oil

[Gacataki]

Hi all.

Looking for advice please.

I'm a new owner of a 1980 CB750. I noticed that since servicing the bike, my clutch dosen't seem to work as it did before. Could always shift to neutral, but now have to first switch off the engine.

I used 15w40 oil that I had. Was this a mistake?

I have checked various sites, incuding this, but get so many dfferent recommendations.

Please guys, what should I use?

 

[Bo82CB]

I don’t think oil will cause that condition but not an expert. If it’s going to make you feel better, I use 15w40 diesel engine oil as well because I have it at work in abundance and it does excellent job, my bike shifts smoothly.

 

[Gacataki]

I don’t think oil will cause that condition but not an expert. If it’s going to make you feel better, I use 15w40 diesel engine oil as well because I have it at work in oil.abundance and it does excellent job, my bike shifts smoothly.

Thanks. That is exactly what I used. 15w40 diesel engine oil. (Leftovers from servicing my Fortuner).
Actually just spoke to our local 'old bike' mechanic, and he said very strongly, that I should change it immediately!!. Back to square one. LOL...

 

[Gacataki]

I don’t think oil will cause that condition but not an expert. If it’s going to make you feel better, I use 15w40 diesel engine oil as well because I have it at work in abundance and it does excellent job, my bike shifts smoothly.

 

[Bo82CB]

Thanks. That is exactly what I used. 15w40 diesel engine oil. (Leftovers from servicing my Fortuner).
Actually just spoke to our local 'old bike' mechanic, and he said very strongly, that I should change it immediately!!. Back to square one. LOL...

Just curious, what did he say to change it with!? Because in 1982 when that bike came from factory probably had 10w40 conventional oil in it… which is how much different than what you put in!?

 

[Gacataki]

The mechanic said must use 10w40 or 20w50... for petrol engine.

 

[Gacataki]

Think I'm rather going to check clutch adjustment. Anyone know the correct procedure for using the adjuster on the clutch cover? Please.

 

[Bo82CB]

The mechanic said must use 10w40 or 20w50... for petrol engine.

Lol, that engine definitely knows what engine oil is for gas and what for diesel engines!

 

[Gacataki]

Yip... Cos the mechanic told her.

 

[Biebs]

Shell Rotela 15/40 diesel oil is Jaso approved for motorcycle use. Check the API approve on any oil you use - friction modifies are not good for the wet clutch in motorcycles.

Detail matter!!

 

[Commander_Chaos]

If you can't shift to neutral the clutch is dragging. Consult the manual and adjust the clutch before doing anything else. While thicker oil could conceivably cause dragging, it's more likely that the cable has stretched or that one of the other parts in the system has gone out of adjustment.
You may know this already but the adjuster on the cable is not the clutch adjustment. The clutch gets adjusted first and then the cable gets adjusted to take up any slack.

 

[SenseAmidMadness]

15w-40 Shell Rotella T4, T5, and T6 are all perfectly safe to use in wet-clutch motorcycles and explicitly meet the JASO-MA and JASO-MA2 standards formulated by the Japanese motorcycle manufacturers. Says so right on the bottle.
Now, if you used a different kind of diesel oil that isn't of known quality or certification, that may be a problem. I believe Mobil's Delvac is also safe for wet clutches but I'd have to double-check. Diesel oil is generally safe for wet clutches because many tractors have them.

Personally I have used Rotella as my "motorcycle oil" in every bike I've owned without a BMW badge on it. (My Beemers are dry-clutch so they get 20W-50 car oil, despite the silly outdated opinions of the Old Farts in the MOA...)

The difference between 10W-40 and 15W-40 is negligible unless you're riding below freezing -- 0 degrees C. The owner's and service manuals have a chart for oil viscosity versus temperature and in higher outside temps our bikes can even use 20W-50 or straight 30W! 15W-40 is no problem at all.

Also, related to your neutral-finding problem, that does sound like a clutch or cable adjustment. I have heard of this being a somewhat common problem on old motorcycles which a lot of owners "solve" by ignoring it. Perhaps you or your mechanic made a tweak to the clutch cable that is preventing it from fully engaging?

 

[Gacataki]

Thanks very much. Please, how do I adjust the clutch at the clutch cover. I can also feel when changing gears, that the clutch is not engaging fully. Thank you.

 

[dirtdigger]

Get a Honda manual

 

[Commander_Chaos]

+1 on the manual. Difficult to overstate the importance of having one. The factory manual is the gold standard and you can probably find a PDF online. If you prefer a physical book like I do Haynes manuals are pretty good. The Clymer ones suck.

 

[Gacataki]

I totally agree re the manual, and do actually have. My query is regarding lubricants.... that have progressed massively since 1980, when the manual was written.

 

[Gacataki]

Hi All.

You know... I joined this group some time ago when I acquired a CB750, believing we could share stories and experiences along the way. I never for one second, thought that I'd be told to 'to get a manual'. Quite disappointing.

 

[SenseAmidMadness]

That's not the way I would treat novices looking for forum advice, personally; it could at least be said in a nicer way.
However, your service manual will list the clutch adjustment procedure out perfectly for you, likely with pictures. And you don't have to wait for people to reply. For routine maintenance items that manual is frankly a better reference than we are. What we're best at is questions the manual won't answer.

What else did you want to know about your oil? I figured we had answered any questions about it further up in the thread.

 

[Gacataki]

Thank you. I'll consult the manual.

 

[Commander_Chaos]

Hi All.

You know... I joined this group some time ago when I acquired a CB750, believing we could share stories and experiences along the way. I never for one second, thought that I'd be told to 'to get a manual'. Quite disappointing.

Sorry, I didn't mean to talk down to you. A lot of novices (like I was) end up going in circles and getting frustrated because they get bad or incomplete advice. Many things, clutch adjustment being one of them, are a sequence of operations that have to be done in a specific order. The manual nearly always gets it right, where a post on a forum could easily leave something out.
"Get a manual" could be read two ways. One would be "stop bothering me with these basic questions". Another would be "there are better sources for this information than me". The latter is the better interpretation, even if it wasn't meant that way.