Chainsaw Repair

Free spinning high rpm engines don't work well with too much compression......

Smaller engines like a 50cc work saw gain lots of torque with over 200psi.

Here's a graph of one of my MS261s compared to a stocker.....



In my world race saws, and work saws are two completely different animals. In the past too many people tried porting a work saw like it was a race saw.....

I've tested bone stock Dolmars with over 200psi.......just saying.

backtracked some numbers to get some torque figures from that graph posted above.  (more intrested in torque curves).

rpm/stock/ported:  (lb-ft)
6K/2.107/2.472
6.5K/1.825/2.415
7K/2.238/2.507
7.5K/2.228/2.468
8K/2.340/2.500
8.5K/2.240/2.504
9K/2.241/2.534
9.5K/2.156/2.559
10K/1.769/2.557
10.5K/1.630/2.368
11K/1.451/2.304
11.5K/1.264/2.200

(did my best to decifer the 11K and 11.5K numbers on the graph)

stock sum avg TQ = 1.957 lb-ft
ported sum avg TQ = 2.449 lb-ft

20% avg increase.
still amazes me to see what an avg gain of about 1/4 lb-ft will do when its moved up the rpm band a few thou

worked out some bmep's to see a different view

stock = 3.97 bar (at peak)
ported = 4.34 bar (at peak)

+8.5%

compliment you on a nice increase that should give long reliable service.

regards
-joe