Fork oil weight??

 .I have an '83 Honda VT750C and  I'm currently using 20wt.  The forks seem a
little stiff in sub freezing temperatues, and a little soft in the hot
weather.

I was thinking of using a 10/30 wt oil, but the only multi-grade oil I can
find is engine oil.

Does anyone make a multi-grade fork oil?
Would this caue a problem using multi-grade engine oil in the forks?

Thanks!

 
It's my understanding that fork oil wieghts don't
really translate well to engine oil weights. I think
I'd stick with a fork oil. 20wt seems a little heavy
also.

 

I'd have thought it was too heavy an oil at any time, actually.

Not to my knowledge. Multigrades only 'change' from one grade to another
(as it were) at temperatures far, far higher than you'll ever get in a
fork.


No, but it would be a complete waste of time because, in practice, it
would only ever operate at the lower end of the multigrade scale.

--
BMW K1100LT Ducati 750SS Honda CB400F SH50 Triumph Street Cripple
If you don't know what you're doing, don't do it. Workshop manual?
Buy one instead of asking where the free PDFs are
chateau dot murray at idnet dot com

 
Ummm, do you have to ride so fast on cold mornings?

Can't you avoid riding over frost heaves and sharp-edged bumps, or
maybe just sit back go slow and relax and don't put a lot of weight on
your wrists? That *is* a cruiser model, yannow...

It would be nice if there was a simple solution, like multi-grade fork
oil that worked as well in the winter as it does in the summer.
Suspension tuners have tried everything from fish oil to automatic
transmission fluid, trying to solve the problem of harsh damping due
to crude damper rod oil flow control.

Sorry, but your forks do have crude damper rods inside them with a few
small holes drilled in them to control rebound damping.

Since the damping due oil flow through those holes is *very* sensitive
to stroking velocity, you can get into a situation where the fork oil
cannot flow rapidly through the holes and you get a very harsh action
as the fork compresses. (1)

Riders of sport bikes lean forward over the short handlebars and
really notice the jackhammer effect of restricted oil flow at high
stroking velocities because they put more weight on the handlebars.

20 weight fork oil is a little heavy, but it's what I use during the
summer riding season in California.

I tried 30 weight oil, but it was too thick for vigorous riding during
the winter months. The heavy oil caused too much compression damping
and the front tire chattered over small bumps and the whole motorcycle
wobbled.

(1) Race Tech, a California company that makes parts for forks has a
part called a Gold Valve Emulator. It's an adjustable oil pressure
blow off valve that sits on top of the damper rod and blows off excess
compression pressure.

I dunno if Race Tech has any GVE kits especially intended for the
VT750 Shadow, but if you knew what the internal diameter of the fork
tubes was, maybe Race Tech could advise you as to which GVE would fit
in your fork tubes.

 

<snip>

In other words, you have failed to answer the OP's questions
*completely*.


--
BMW K1100LT Ducati 750SS Honda CB400F SH50 Triumph Street Cripple
If you don't know what you're doing, don't do it. Workshop manual?
Buy one instead of asking where the free PDFs are
chateau dot murray at idnet dot com