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S&S Knuckle KN74 in aftermarket frame

Post Tue Oct 27, 2020 7:31 am

Posts: 3
Hi Guys

I am new in this forum, but i need some help.
I live in Denmark and have recently bought a new Knucklehead frame from VG Motorcycles in Holland.

This is the late 1947 frame without the bullneck, very nice and correct.
I have an S&S Knucklehead engine KN74", which i ran in my panhead frame, with a spacer mounted in the front motor mount.

Now i have mounted the KN74" in my new frame with stock specs, but the upper motormount is way off, and can not be mounted (see pictures)

I had the S&S spacer (which comes with the engine) for the front motormount in my panhead frame, i believe the overall height of this spacer is 5/16", but not 100% sure of the height.

I wrote to VG frames in Holland, and they tell me i maybe need a spacer with height 3/8"

Does the S&S spacer also needs to be mounted in my knucklehead frame ?
After what S&S writes in their description, the spacer should not be necessary in a Knucklehead frame.

It looks like the spacer makes sence to mount, because the engine would be placed higher, and thats what i need.
But i am affraid of, if i place the spacer in the front of the motor, the rear mounting on the frame/engine will be "angled" upwards, which is not correct


Hope some of you guys have had some experience with an issue like this.

I write this because i want to mount everything the correct way, so i dont break my engine or frame.

Best Regards

Rob Vloet
Aarhus, Denmark
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Posts: 2773
Location: Los Angeles, CA
A spacer is not needed to put a Knucklehead engine in a Knucklehead frame. If your "Non Bullneck" frame is for a Panhead then you do need the spacer.
I bought a replacement Knucklehead frame from V Twin. The top motor-mount on it was off like your picture shows. It was easy to grind off the welds and reposition it to correctly fit the gas tanks and top motor-mount.


Posts: 399
You mention an S&S engine. Were the cases cast to Knucklehead lower front motor mount dimensions or Panhead? They are different locations and may require spacing,/shimming in the new frame.
As Chris suggested also, check the tank fitment and the motor mount to seat post distance to make sure it isn't just the mount location.


Posts: 3
Thanks guys

The lower mounts on the motor/frame fit very good, and i almost didnt need to shims it, in to the frame.


The S&S engine comes with a front mount spacer (if it needs to go in a panhead frame) since the panhead front mount is lower than knucklehead.

I will have to customfit the top motor mount.

I have some original 1954 tanks to put on the bike, and they are fitting well on the frame, but placed a little higher.

I have seen some pictures of 1947FL bikes, where the gastank is placed higher, is this right ? see picture

I just want to have the gastanks to place lower, but it is hard to tell, when it is on the "lift" maybe you guys have a trick for this also ?

I have measured the frame, if it fits a panhead engine, and it does not, so i think the dimensions on the frame are very correct.
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Posts: 3
RUBONE wrote:
You mention an S&S engine. Were the cases cast to Knucklehead lower front motor mount dimensions or Panhead? They are different locations and may require spacing,/shimming in the new frame.
As Chris suggested also, check the tank fitment and the motor mount to seat post distance to make sure it isn't just the mount location.



Hi RUBONE

Do you have a drawing of the original frame, to check the measurements from motormount to seat post ?

Post Thu Nov 05, 2020 12:00 pm

Posts: 22
Location: Sand Hills of Nebraska
It looks like you have more clearance both around seat post and under the top bar then my stock frame. Manufacturing back then was a little more hit and miss back in the day
It's a hard life if you don"t weaken.


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