Kamran Nili                     Boynton Beach, FL                 kn592@yahoo.com                          6/2/2007

Upshur Twin 4 cycle Engine .750 inch Bore x .720  Inch Stroke, Open crank with air cooled cylinder.

I started building this engine on February of 2006 on a part time bases with lots of break in between and just finished it on May of 2007.

I did the first test run on Sunday May 27 and the engine fired up on the 4th flip and lasted for almost 30 seconds.

Play around with it for a while and the best I got about 45 seconds of run time. I think it has a lot to do with the adjustment of the carburetor throttle and the mixture needle. 

For the carburetor, I'm using an old OS 25 FSR carburetor which I think is the source of problem for not delivering the fuel correctly.

I'm not very happy with the original design of the distributor, so I'm thinking to re-design that again.

 The Ignition system uses a 6 volts battery with a Hall sensor and it is my own design. I'm very satisfy with its performance

The ignition coil is a 6 volts Arctic Cat Snowmobile Ignition coil (very useful in Florida). I like this ignition coil a lot and used it on my other engines and always delivers a good hot spark.

 I'm using 2 sets of pistons. 2 with cast iron rings and 2 with O-rings. The engine doesn't run with the cast iron rings and is because I'm not getting a good compression (need to learn how to make a ring correctly).

 The 2 pistons with the O-rings have great compression.

On one of the piston, I have a double seal Viton O-ring and the other one has an o-ring from Home depot (pluming department). The reason I used one from Home depot is because I ran out of Double seal Viton O-ring. Interesting observation was that after total of 5 mins of run time, the generic O-ring from home depot got busted and caused too much friction to the point that It was very hard to turn the flywheel. In past I have used the Viton O-rings and they last forever. My single cylinder Upshur is using a double seal viton o-ring and it has been there for almost 3 years without a replacement and gone through over a gallon of fuel.

 For the fuel, I'm using Coleman fuel and 10% WD40. For the test run I did not put any oil in the crankcase and just lubricate everything very well.

Copyright 2007,  Florida Association of Model Engineers and engine builder as noted above, All rights reserved.