Poulan 2450 - Muffler Mod & Trouble tuning

[JB Weld]

Yall go easy on me....I am new to CAD and she has been a cruel mistress so far.

So my neighbor's old 2450 needed new fuel lines and I volunteered to work on it. Nothing like experimenting with someone else chainsaw. I wanted to try porting a muffler and I figured this would be a perfect candidate because it was not mine. Besides, he said he was "through with it, and I could do whatever I wanted to it. He did not care."

So I started reading up on modding a muffler. Then off came the muffler and out came the drill bits. I drilled a couple of 5/8" holes through the interior baffle and reinstalled it with the spark screen intact. I then drilled a series of 1/8" holes in the front of the muffler right where the edge turns down into the recess on the front of the muffler. I think there are 6. I installed new fuel lines, cleaned it all up in general, and got it all put back together.

I set the idle screw until it just kissed the throttle, then started with the L/H screws 1 1/2 turns out. It fired right up and I let it warm up. I got it to idle really nice, and when I hit the throttle she comes up to WOT smooth and fast. It sounds nice (she is not screaming and sounds ready to eat).....and I think !!!! The problem is that after I let off of WOT, she dies. She will not start up after that. I mean she wont pop or anything, so I assume she is flooded like crazy. I let her sit for a while and then start again. I have done this three times with the same results.

Did I open the muffler up too much? Am I too rich on my H screw?

 

[Rockjock]

The last Poulan I worked on needed 1 turn for both the L and the H from Lightly seated. Give that a try.

 

[JB Weld]

Well, I figured it out. I had to let the L screw out about 1/4 turn. Throttle response is great and she idles down just fine now.

I just cannot believe how much of a difference porting the muffler made. It is still a Poulan, but that sucker roars and was eating through an old chunk or red oak like a champ!

 

[leecopland]

Does it 4 stoke out of the cut? Then clean up once into wood. This is a good indicator that you are not running too lean. Easy to burn up a saw running too lean.

Welcome to the site.

 

[scottr]

Yall go easy on me....I am new to CAD and she has been a cruel mistress so far.

So my neighbor's old 2450 needed new fuel lines and I volunteered to work on it. Nothing like experimenting with someone else chainsaw. I wanted to try porting a muffler and I figured this would be a perfect candidate because it was not mine. Besides, he said he was "through with it, and I could do whatever I wanted to it. He did not care."

So I started reading up on modding a muffler. Then off came the muffler and out came the drill bits. I drilled a couple of 5/8" holes through the interior baffle and reinstalled it with the spark screen intact. I then drilled a series of 1/8" holes in the front of the muffler right where the edge turns down into the recess on the front of the muffler. I think there are 6. I installed new fuel lines, cleaned it all up in general, and got it all put back together.

I set the idle screw until it just kissed the throttle, then started with the L/H screws 1 1/2 turns out. It fired right up and I let it warm up. I got it to idle really nice, and when I hit the throttle she comes up to WOT smooth and fast. It sounds nice (she is not screaming and sounds ready to eat).....and I think !!!! The problem is that after I let off of WOT, she dies. She will not start up after that. I mean she wont pop or anything, so I assume she is flooded like crazy. I let her sit for a while and then start again. I have done this three times with the same results.

Did I open the muffler up too much? Am I too rich on my H screw?

JB, it was not necessary to drill the baffle. The baffle with the two slots and twelve holes has a open area of 0.474 square inch . The rear outlet open area is 0.093 square inch . Your six 1/8" holes only added 0.073 square inch to the outlet . Next mod try a .25" by .50" hole downstream from both louvers which will be about a 10% of displacement opening . This works well for my 044 and my PP220 .