Chainsaw modder's question and tool list.

I'm thinking if we put our modding questions in one post, it won't clutter the heck out of the chainsaw board, and the info won't be spread out over a bunch of different threads.

First question I have, and I know Jay has mentioned it before, is scales. I would like to get a gram scale, but I don't know what max. weight I need, or what resolution. How much does a jug weigh, and is .1 gram res. enough, or should I go for .01?


Anyone else have any questions, feel free to put them in here.

Don't recall ever mentioning scales, Dave. Perhaps you have it confused with a compression tester, or tach? Why would you want to weigh a jug?
Weighing a piston is sometimes interesting, to see how much you have lightened it up.

It was in reference to lightening up pistons, but I'm curious to know how much a jug weighs. I'm guessing .1 gram resolution is enough for pistons? Thanks.

I think Dave is getting his cocaine sales/ distribution business confused with his saw modification business.

I think a few might weigh a piston just for a reference .I can't think of any other reason .

If you cut a pop up or do some flow work on the windows you will cut some weight but by how much I'm clueless .

There were definitely enough hidden scales at that site, for anyone wanting to do that sort of thing.

Have never weighed a lightened piston, myself, other than feeling it in my hand, and looking at the aluminum dust on the floor. Prefer to let the rpms do the talking.

Usually I'm wearing the aluminum .Might start a new fashion trend .Stranger things have happened .

Next question. I've seen it mentioned that you want a compression gauge that has the bleed valve as near the saw as possible. I've got one from Sears, but it has the bleeder up by the gauge. Any leads on one that has the valve at the other end? Thanks.

Jay, how do you measure the amount of difference a lightened piston makes? When tuning my 394, I noticed that it would four-stroke well past 13k. I have it set at the factory 12,500 now, but it really four-strokes, until you put it in the log, then it almost seems to straighten out and pull really hard, almost like it has a turbo on it. Strange sensation. I've only removed a little weight from the piston, and some from the ports, but I didn't change the actual size of the port on the piston end. Don't know if these changes may be affecting the four-stroke rpm or not. Any insight appreciated.

There are several things which will determine what speed the engine runs at .Porting ,carboration ,ignition timing ,exhaust .

Where ever it runs ,barking [4 cycling ] is where it runs . The speed in the air is just noise,doesn't really mean a lot ,it's what it does in the wood that counts .

Some people use a tachometer all the time yet I know some of the fastest saw racers on the east coast that don't even use one . They tune by ear ,which is what I do .

A compression gauge and a tach are good reference tools but they don't tell the whole story .

Truth in what Al says. Still, I use a tach to see where the rpms are at, as I'm curious about the gains, and knowing where the stock numbers are, gives me a good reference point, and seems to further my understanding a bit for when approaching future mods.

Lightening the piston isn't just lightening the piston, as usually you would be wanting to also enlarge the windows and round the corners along with beveling the edges, to give better gas flow from the crankcase out. So, I interpret it to be the lighter piston in combination with more combustible mix getting into the combustion chamber, to afford the rpm and torque gains, along with how the cylinder was modified.

It would be interesting to just work on the piston with no other alterations, then put it together to see the amount of gain. You can generally remove a lot of material off a piston, I'm thinking that alone is going to give 500 plus increase in the revs. Better gas flow efficiency is really a big plus in a mod, but as Al mentions, what is happening in the wood is the bottom line. Some saws get all hyper, but then fall flat on their faces in the cut. Sounds like you've done a good job there, Dave, if the saw holds steady or gains rpm as the cut progresses.

I bought a cheap compression tested from Baileys, with the valve at the hose end. It's Taiwan job, and works OK. I calibrated it with an expensive tester, and the readings were close. Still, it's pretty cheaply made. I'd like to get a Snap On, or some other good one.

Thanks. I am not sure the small amount of grinding I did, made much of a difference. I just polished the windows and got rid of the casting sprues on the piston. The saw seems to run much better in the cut, that's for certain.

I don't actually think I gained any rpm's on the 38 mag because the exhaust was acually longer than stock . Stock was 99 degrees and as it is now 102

It however has tons of torgue for 72 ccs and actually cut faster in 10 by 10's than the 066 and 2100 Huskey I ran the same wood at the Ohio GTG .

Square cants are not a true test of what a saw will do but does give a reference of what it should do . Other things must be considered for it to be a good work saw.Like does it start without wearing your arm out .Does it run cool .Do you have to baby it etc . A wimpy no torque saw is a pizz poor choice for a work saw .,

I'll take torque over revs for sure, for a work saw, especially in larger wood. Higher revs do add to the picture, though. Interesting to read that the three degrees in exhaust duration increase didn't alter the rpms, but that's a pretty minimal increase, I believe. Modding an 036 gave awesome torque, but much lesser so on the rpms. Entering the wood can be problematical

I wish I could figure out how they get the high revs out of some of the stock saws, like the 242xp at 15,500. Nothing appears to be unusual when breaking it down and examining. The crank and connecting rod could be lighter than usual....carb jetting too....? I modded it, and now it sings even higher, my favorite saw for limbing and small bucking. Raising the compression sure gave some kickazz to the thing.

To make a long story short I screwed up when I cut the base. Took too much off and had to change gaskets which is why the exhaust came up long .

Had I raised the ex back up to stock or even taken another two off it would have jacked the rpms a tad .How much I don't know .

You have to remember though on that mod the intake was taken real wide and lowered and the exhaust was taken to around 65 percent and belled .So it's breathing real good .Just maybe hanging a tad too long on the power stroke to gain any r's .