HOTSAW! Not and audi, but still cool
Posted: Mon Jun 15, 2015 9:56 am
My good friend is a professional lumberjack competitor. He qualified for the Stihl series finals next weekend and I was helping him get his hotsaw tuned up. Doing some experiments with exhaust pipe setup and timing.
Strangely it makes the most top end power with the ignition timing retarded to the max adjustment of the range. Two stroke pipe design and scavenging effect definitely comes into play here, but i barely understand it, and surely not enough to really explain it.
With timing more advanced it was more responsive to throttle input, but that doesn't really matter since top end power is really all that matters.
Hes been competing with this saw for several years, and is actually to the point where he needs more power. He is stalling it out on the upcuts when going for time. It actually cuts faster with less pressure on it.
The current setup is a 2001 rm250 motocross bike engine with a 265 big bore kit, running c12 gas. The powervalves are operated via cable from the throttle trigger. The saw has been very competitive against many other much larger cc saws.
Here is Matt pulling so hard it stalls out.
https://www.youtube.com/watch?v=e3e-Mvh ... e=youtu.be
not sure if non-facebook users can see this. This is me running it like a pansy. Just starting this thing is a scary and difficult task. The gyroscopic forces and insane vibration makes it a serious handful. Not sure what it makes for HP, but its probably in the 60+ range. I've run it before and it was just as scary as I remembered.
https://www.facebook.com/matt.marks.397 ... nref=story
hes trying to find a ktm300 to build a new saw. Hes also considering higher compression professional porting with a custom pipe to match.
Strangely it makes the most top end power with the ignition timing retarded to the max adjustment of the range. Two stroke pipe design and scavenging effect definitely comes into play here, but i barely understand it, and surely not enough to really explain it.
With timing more advanced it was more responsive to throttle input, but that doesn't really matter since top end power is really all that matters.
Hes been competing with this saw for several years, and is actually to the point where he needs more power. He is stalling it out on the upcuts when going for time. It actually cuts faster with less pressure on it.
The current setup is a 2001 rm250 motocross bike engine with a 265 big bore kit, running c12 gas. The powervalves are operated via cable from the throttle trigger. The saw has been very competitive against many other much larger cc saws.
Here is Matt pulling so hard it stalls out.
https://www.youtube.com/watch?v=e3e-Mvh ... e=youtu.be
not sure if non-facebook users can see this. This is me running it like a pansy. Just starting this thing is a scary and difficult task. The gyroscopic forces and insane vibration makes it a serious handful. Not sure what it makes for HP, but its probably in the 60+ range. I've run it before and it was just as scary as I remembered.
https://www.facebook.com/matt.marks.397 ... nref=story
hes trying to find a ktm300 to build a new saw. Hes also considering higher compression professional porting with a custom pipe to match.
