Viperhead on YS91- shims???

[cmsilvoy]

No replies on RR.
The freaks seem to be more "Oneal's" friendly and saavy.

Running a VH on the YS91 using Magnum 30%, what shims should I use?
I've tried calling James but I think he's on vacation for the week of the 4th ;)

Thanks for the replies.

Chris

[Gary O]

I just run the shims he sends with the head on all my YS engines. The shims don't seem to be quite as important on the YS as they are on the OS, at least from my experience. The most important thing I've found is gearing. I started running 8.45 on them and they are a totally different motor. Still not quite the punch of the OS but good enough for 3D.

[DavidH]

Chris,
The Viperhead for the YS comes with a .004 shim. Using Cool Power 30% or Powermaster 30%. The .004 shim is all you will need.

With the Magnum 30% will will most likely need to use .008. This the stock shim that is under the stock YS head. If the motor detonates with the .008 shim. Then also add the .004 shim for a total of .012 in shims.

We tested the Viperhead with thickness of shims on the YS when James developed it. The .004 was what ran the best with CP 30 and PM 30. With the Magnum your going to need more shimming.

David

[cmsilvoy]

Thanks all.
I finally did talk to James this morning and confirmed:

.004 is fine
If hot climate, .008 may be better

I will get the shims (I do not have any at all) and try it both ways. The engine is in a Sylphide 90 and the head is easy to retreive after removing the fan shroud (I did the Vigor cooling mod).

We'll have to see how it goes.

Hopefully this machine will begin Class 1 competition next year :)

Chris