August 2000 News 
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   Warpath Engine Case Update
   By Lyle Landstrom
As I'm writing this, the pattern for the right side case is 98% finished. I had to make some adjustments to the thru-bolt spot face heights, otherwise it would have been finished. This week I plan to do the detail sanding on the fillets in these areas and make the flasks to hold the sand for the casting. These items might be finished as you read this.

For the left hand case, I'm going to appeal to the readers for some help. If you've been following this project, you'll know that I had a factory blueprint for the right case. I do not have one for the left side and therefore have to create a drawing. Many of the features on the right side are symmetric with the left such as general outline and thru-bolt locations. What I do not have are Z-Axis dimensions, inner primary mating surface dimensions and cylinder the deck configuration.

The attached drawings are my best guess for the left side case. Let me apologize for the lack of quality and consistency as this article and drawing was done as an afterthought a couple of days before the VI deadline. Until I get a casting to the machinist, I'm a one man show and do my own proof reading and plan checking.

It had been my original intention to cast the right side, send if off to Abbott Machine, and take a breather while I wait for the machinists comments. Upon which I would start the left side. However, if I can got the dimensions of the left case squared away, it will give me a head start and can actually start the main portion of the pattern before I hear back from Rick Abbott. I still plan on not finishing the details until I hear the results of machining the right side. There could be some minor inaccuracies in the right pattern which will need adjustment and could also affect the left side case pattern.

The Drawings

I need measurements for all the dimensions in green. You'll notice that some have dimensions filled in and others have just a question mark. The dimensions which are filled in were pulled from a Sport Scout set of cases and need verification as my cases are not very good. There is a purple circle with a letter in it to simplify the information as it gets back to me. Each letter corresponds to a dimension. When measuring, instead of describing the measurement and increasing confusion on my end, I'll know that all the measurements are described the same way, with a letter. There are also some comments in red  which perhaps someone might be able to get back to me on. All dimensions needed are for Big Base cases with the exceptions noted. 

As I have pointed out before, I am going to offer two different versions. One with the large 648 style output boss and the other with the normal Sport Scout output boss. This will allow the rider to be able to run a generator or not. The Sport Scout version (generator) will still be stronger than a regular set of cases because of the increased size of the inner bearing boss. And additional webbing on the outside surface.

Lets get to measuring. Please refer to the drawings.

Measurement  Description
A Crank Bearing Boss inside diameter of finished surface.
B Gasket surface To inside Case surface.
C Gasket surface To Crank Bearing Boss finished surface.
D Gasket surface to inside Sump surface.
E Gasket Surface to Bottom Bolt Boss.
F Top thru Bolt distance - Gasket to Spot Face.
G Height of Inner Primary Mating surface.
H Diameter Of Crankshaft Boss (Sport Scout).
H-2 Diameter of Crankshaft Boss (Big Base 648).
I Length of Crankshaft Boss (Sport Scout).
I-2  Length of Crankshaft Boss (Big Base 648).
J Angle from Inner primary Mating surface centerline to Front Thru Bolt. It is not in line with the x-axis of case but rotated clockwise about 5 degrees.
K Angle From Front Cylinder centerline to center of Timing Plug. (Same as ignition advance of front cylinder???)
K-2 Radial distance from center of crank to center of Timing Plug.
L Front Thru Bolt distance (spot face to gasket), also verify this is the same for all 3 front Thru Bolts.
M Rear Thru Bolt distance (spot face to gasket), verify the same for all 3 rear thru bolts and bottom.
N Cylinder Base longitudinal length.
O Cylinder Base transverse length.

In addition to these measurements, you'll note that the drawings ask for verification of a chamfered area near the serial number location. As well as the oil directional vanes on the inside of the case. You'll also note that the drawings show a normal 648 set of cases. None of the new features are drawn in. Some of these features such as additional flange size around the bolt bosses is dependant on how they work and fit on the right side case which is being cast next week and then sent off for machining.

I would like to thank everyone who has helped me along the way and appreciate any help you may provide me. With everyone pitching in on this, it truly is "The People's Motorcycle!."

I have worked pretty consistently on this the last several months. The proto casting for the right side is about a week away. It should be ready before the end of the month.  Although I have worked hard and have probably entertained more than a few people, I can sit back and envision hundreds of VI Listers tearing down their 648 Daytona Big Base Scouts just to get me these measurements. I thank them all. I'll send results of measurements to Moen on a spreadsheet when all this is done. It'll make an interesting comparison and perhaps an ambitious person can write a paper on statistical quality control when all this is over.

Send all results to

Again, Thank You,

Lyle Landstrom


More Warpath Info:

Main Warpath Project page

Original Big Base article

DIY Pattern Making and Casting

Click on pictures for full size




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