Clutch problem

[rick deford]

I recently entered my freshly rebuilt 74 Berkshire in a VMX race. The first time I ever raced a 100 of any kind.
One of the problems I'm having is at the starting gate when I engage the clutch at low rpm's everything is ok, but, when I rev the motor for the start the bike wanted to get going.

I know I have something wrong, but, I don't what. Knowing me it's probably something simple or, over looked.

It's a new clutch basket, plates, springs, 700cc Golden Spectro 80W. Pretty sure I have the clutch adjusted per the manual.

Any suggestions,

Thanks,

Rick

[chicagojerry]

what kind of clutch lever are you using? magura or japanese replacement?  chi jer

[rick deford]

It's a Magura.

[wfopete]

Rick,

GS 80WT is pretty thick, although a good oil, it may be creating parasitic drag within the transmission. Parasitic drag (also called parasite drag) is drag caused by moving a solid object through a fluid medium. Parasitic drag is made up of many components, the most prominent being form drag.

Oil is cheap, you may want to drain and refill with ATF, which typically is about a 20WT oil, and see what happens.

I like ATF because:

It's cheap
You can find it almost anywhere
It's has high detergent properties
Clutch plates like it

Also double check your clutch adjustment(s)to be sure you are mechanically in spec and that there is no binding of components creating the condition.

Pete Petrick
175 Jackpiner
Slow but Good

[Larry Perkins]

Pete,

Spectro 80wt is not a true 80wt like a gear lube.  It is like Belray Gearsaver and the true viscocity is far lighter.  It is like the Hipoint Gear Oil we used back in "The Day".  In fact the Hipoint oils were made by Spectro and re-labeled.

Rick,

You could try the ATF as it was used by a lot of the Penton riders way back and today but I bet you are in need of fiber clutch plates and or new springs assuming your adjustments are all correct.

Larry P

[gooddirt]

I think you need to check and maybe adjust the brass inset adjuster in the side case cover. LG

[t20sl]

Rick:
First, I think you mean when you disengage the clutch (lever pulled in to bars).  
Possible things also could be too much oil in clutch.  this also causes drag like Pete was talking about.  Warped clutch plates might but I would think you  would feel the drag at low rpms also.
Also make sure your free play is correct, though again it would happen at low rpm some too.  Recheck your adjustment inside.  My bet is oil weight or level.  Worn clutch plates would slip not drag usually.
Ted Atkinson

[Larry Perkins]

Thanks, Ted.  I misunderstood.  I thought Rick meant when lever was released.  I think you are on it level, warped plates, or one of the adjustments(at lever or in case).  If it was drained through drainplug often all of the oil does not get out.

Larry P

[rick deford]

Ted - You're right. The clutch lever was pulled to the bars. I meant to say with the clutch disengaged. I sure hope it's not warped clutch plates, because they had about 20 minutes use on them.

Is 700cc too much oil?

Thanks for all the imput guys.

I'll pull the clutch and check for warped discs. Any helpful tips on making adjustments inside the case?

Thanks again,

Rick

[gooddirt]

If you have a new NOS clutch combo unit out of the box I would not worry about warped plates. How far out is the top cable adjuster on the lever? I just went through this with my 100 this weekend. LG

[Ron]

Hi Guys,
If you clutch experts wouldn't mind a little assistance here.
The clutch in my 125/6b motor has new fibers plates and springs with 80wt Bel-Ray Gear Saver.
I loose the free play adjustment after a couple laps.
The adjustments always comes back after the motor cools down,
but its no fun in a Gran Prix or long race, when the clutch won't disengage.
Otherwise it works great (when its cool), easy to find neutral when running and doesn't slip.
Appreciate any ideas for a fix.
Thanks, RonW

[Larry Perkins]

Ron,

Were the fibers NOS Sachs or aftermarket?

Larry P

[454MRW]

Just something to check: Is your clutch cable new or original and what brand? Some new cables and most used cables tend to stretch which can cause the type of problem you are experiencing. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1980 KTM 175-400'S

[Ron]

Hi Larry,
Not sure, got them from Terry Everett about a year ago.
RonW

[Ron]

Forgot to add new Terry Cables.