Topic: CB 500 four clutch / shifting problem

[trebot]

Have researched and read about everything about "hard to shift when gets warmed up".  Oil seems to be a factor (as well as poor design). 
  Would synthetic maintain better viscosity when hot?
  Do clutches like synthetic?

[DaveBarbier]

Synthetics are slipperier, but as long as its motorcycle wet clutch oil I'd say you'd be good.

I've used some full synthetics and had hard shifting problems, but I've also used other synthetics that are good. The full petroleum Maxima break in oil I'm currently using (new motor) performs well as well as the Spectro golden semi synthetic I've used in the past. 


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[TwoTired]

Clutches don't care if the oil is synthetic or not.  Synthetics generally have a high temperature withstand before breakdown.  That's why I use a synthetic blend oil, in case the engine gets hot and there is no airflow over the engine cooling fins.  Just a bit of extra protection.

What clutches do care about is the additive package blended into it.  Some additives will make the clutch slip, such as what is found in today's Auto oil offerings.
That's why you want a motorcycle specific (for wet clutches) oil.  Or experiment with the oil intended for diesel motors.

I suggest you use a motorcycle specific oil until you get the clutch sorted.  Then experiment with other oils if you think that is a good use of your time.

In fact, for the period of diagnosing clutch issues, why not go for what Honda recommends for the bike, even Honda Branded.  However, I would certainly avoid oil with added Moly, while you get the clutch sorted.

Anyway you can chalk up the added cost of Honda oil to a diagnostic aid/tool.  And if it fixes your clutch issue, it's actually cheaper than replacing a clutch.

Back in 1975, I acquired a 1974 Honda CB550, that was wrecked.  Had 1500 miles on it.  I replaced all the bent bits and got it running pretty well.  But, the clutch would slip and it could not be adjusted out.  Speaking with the limping crash survivor, he had added STP to the engine, thinking it was a good thing.  OK for the engine, NOT ok for the clutch.   It took ten oil changes for the clutch to regain close to full operation and not slip when hammering the throttle in top gears.  I don't think it ever fully recovered.  But, I wasn't too disappointed about never being able to pop wheelies or do burn outs.

Cheers,

[jonda500]

A failing clutch cable can cause this. I've also heard that the early model steel pushrods can cause this symptom.

Try running a little less free play in your clutch cable?

John

[HondaMan]

The 500 has a unique clutch adjustment technique, not documented in Honda's manuals very well. This is due to the clutch rod not extending with heat quite as far as the engine cases do: the engine gets wider than the clutch rod when hot.

To cope with this, adjust the clutch this way:
when [stone] cold, adjust the cable at the handlebars to be 1 turn out. Then set the lifter on the engine case to just barely take up all the slack in the cable, so the lever immediately pulls up snug: no loose slack there, please.

Now, when the engine is cold, the clutch slip point is slightly further out on the lever until you have pulled about 4 shifts. After that, it will move in to about 3/4" of lever slack, as indicated in their manual.

There have been various attempts over the years to make clutch rods that match the growth of the engine width, but most of those were of soft enough alloys that they wore or broke easily. Honda fixed it in the 550 by moving the clutch lifter over to the other side of the engine where it operates directly on the clutch, instead.