Chainsaw Repair

Yes it confirms it, but for me it clairifies some things too.

If factory RPM max is to be respected 85%

Stock Saw up to 125% if RPM is increased above factory spec

Modified gains can be found over 150% if speed is your objective

I want to do some testing on heat and fuel consumption next, bought an IR temp gun yeasterday.

Like the spagetti method, KISS

As far as any ruels of thumb off the size of the exhaust port flange, I would dump that idea esp if the saw has been modified.

For the fuel test, I rigged up a 2 oz (60ml) bottle with 3 lines, one for fill, one breather, and one to the carb. For each test I filled it to the top of the lines, so I should have been within 1 or 2 tenths of a ml each time. After each test I refilled the bottle with a graduated syringe. Using the modified saw and square chain.

For the test I put on a muffler opening and tuned the saw by ear, double checked the RPM on the tach, shut it down and refilled. Then cold started and made 5 cuts in 10.5 inch poplar, shutting the saw down as the last cookie fell.

Here is the fuel consumption numbers ml for 5 cuts

17.0 Opening 0.09
16.4 Opening 0.18
15.8 Opening 0.27
15.0 Opening 0.36
14.8 Opening 0.45
14.6 Opening 0.54
14.9 Opening 0.63
16.2 Opening 0.73
17.2 Opening 0.79
17.4 Opening 1.50

Fuel Efficiency acctually improved as the muffler was opened up, but dropped off about the same opening as improvements started to decline on cut times, only with very large openings was fuel consumption worse than stock. Don't know if this would be the same with a stock saw?

By time the saw uses more fuel as the muffler is opened, so the tank gets dry sooner, but the woodpile gets bigger faster. Too a point.

But I think this is just part of the story, It seams there is a lot of LS ajustment made, and a saw spends a lot of time at idle, so need to check that too.