Question about air filters and carburetor adjustments

[tntatro]

Hello, I have two chainsaws that I suspect are running rich due to poor air flow. One is an 038 magnum and the other is a Chinese ms381 clone. They both have aftermarket air filters that seem to function well but in order to get the saws to run properly the H screw has to be turned to about 3/4 out from closed. If I turn them one turn out then they both run way too rich and 4 cycle badly. I also have a Stens air filter that has better air flow but it has problems with the choke lever which makes the saw hard to start.

Another interesting thing is that the clone originally had a carburetor with a compensator. I replaced the carb with a used Bing carburetor without a compensator. I decided to put the compensator on the bing carburetor and see if that made a difference and it did but then I couldn't turn the saw sideways without it stalling so I had to take it off.

My question is, has anyone had similar problems with this model saw and is this just a situation where I need to use an OEM filter? The aftermarket was $6, the Stens about $25 and an OEM goes for around $40 +. I've been running the clone and it seems to be fine but I don't want to run the magnum this way because it has a NOS piston and cylinder.

Here are pictures of the filters. The yellow ones function perfectly other than poor air flow. In the pictures the Stens is the brown one. It has good air flow but the choke is crappy. At first it would start fine but the choke spring was too weak and the choke lever would flutter and the saw would run too rich no matter what the setting. I put in an OEM spring and now the choke doesn't engage well and it's hard to start.

 

[HarleyT]

How did you put the compensator on the Bing?

 

[tntatro]

How did you put the compensator on the Bing?

What I mean by compensator is the plate that screws onto the metering diaphragm side. The aftermarket carburetor had a plate with a pipe that sticks out. There is a grommet that covers the carb screws that also has a hose on it which connects to a fitting on the air filter and the pipe on the carb plate. I had the air filter fitting plugged with a screw when running without the piped plate. Maybe it's not called a compensator, I just thought that was what it was called. With that piece on and connected to the air filter the saw would start and run good and the settings were normal but it would stall when I turned it clutch side down. Without the piped plate the H has to be 3/4 out and the L 1 + 1/2 out and it seems to run perfectly without changing idle speed when turned. I've actually milled around 200 board feet of 1 inch thick lumber with it this way and it still seems fine. I just don't want to take chances with the 038 magnum.

 

[HarleyT]

I know what you mean, but the "carb plate", as you call it, did it fit? The Bing is a unique carb.

 

[tntatro]

Yes it fit, the aftermarket carb is also a clone. The entire chainsaw is a clone of the Stihl ms381. It's almost the same as the 038 magnum except it has a decompression valve, the bar tightening screw is on the side and the carburetor has the compensator. Some of the repairs I have made I used Stihl parts instead of aftermarket.

 

[Mad Professor]

I brought up OEM stihl filters for all my old saws as some are/will be soon NLA.

I've had problems with aftermarket filters on my 026, no problems with OEM.

 

[tntatro]

I brought up OEM stihl filters for all my old saws as some are/will be soon NLA.

I've had problems with aftermarket filters on my 026, no problems with OEM.

Thanks for the reply, it looks like that may be the best way to go. I'll probably get OEM for the magnum and run the clone with cheap parts.

I originally wanted to get an 038 magnum and add a velocity stack and foam air filter for better air flow and filtration for milling but I didn't know the choke was in the air filter. I may still try to rig something up on the clone but it will take a little figuring out. I may just sell them both and use my 044. I thought the magnum would be close in power but the 044 blows it away. Not sure if it's due to the air filter or if the rings aren't broke in yet or if the 044 is just simply more powerful.

 

[Mad Professor]

Save the 044/038 for felling/bucking and get a > = 066 for milling

 

[tntatro]

Save the 044/038 for felling/bucking and get a > = 066 for milling

I have two 056 magnums, an 045 super and a 50mm 045 also. I plan to keep one 056 magnum and the 044 for milling saws and sell the rest. The 044 seems to be more powerful than normal. I think it might have been modified or something. The timing seems to be advanced because the starter cord will snap back if I don't pull fast enough. It blows away my 038 magnum and definitely outperforms a stock 372xp I had when I first got it. It's not as powerful as the 045 super but it's close and also much lighter.

 

[Kenton85]

Can anyone tell me if it's better to run air baffle on a 460 or take it off and run the foam insert while using a original hd filter