46cc Plastic Poulan

[Chris-PA]

I often read here about how big a saw one needs for, say, a 20" bar. Usually the consensus is considerably bigger than what I would say. I didn't have any appropriate logs to buck, but here is a video of noodling a 34" diameter white oak round, full bar. It's a cheap Poulan 46cc clamshell saw running a 20" bar with Oregon 20BPX chain:





These saws have been sold under many model numbers, as Poulan, Poulan Pro and Craftsman saws. There are also 36 and 40cc versions, some sold as Jonsereds (2036, 2040), and a few 49cc versions. They are very common, and are light (10.1lb powerhead) and decently powerful saws that respond well to a muffler mod. Unfortunately they have a couple of design defects that make them unreliable.

Mine is a 2001 Poulan 2775, a Type 1 with the early muffler and a chain brake. It's been pretty heavily modified by now, but not all of the mods are really required. First the defects and what I've done to fix them:

1. I got the saw from my Dad because it basically didn't work. The limiter caps made it so it would not run and could not be made to within the limits. I removed them. The fuel line didn't last much longer after that so it got replaced too.

2. The rear A/V spring mount is weak. The spring is mounted at a right angle, and the screws go into the plastic. I replaced one of them with a cap screw, and drilled a hole in the top of the handle so I could access it. I also added star washers to keep the screws from turning:



3. Next the rubber seal for the air box partition is a stupid design and they just come off. I tried gluing it on with Seal All and Yamabond4, but eventually used JB Weld:

 

[Chris-PA]

The rest of the defects are from vibration and the failure to use appropriate locking hardware - things break off and screws fall out. The A/V system is good and you don't feel vibration, but I think these things were enlarged to 46cc without changing the crankshaft, which allowed too much vibration. On the Type 1 saws there is a shield behind the muffler that forms a deflector around the outlet. It will fail and break off, allowing the exhaust to melt the chain brake handle (if equipped). I bought another one, but it quickly broke too. Then I made my own by attaching a sheet of steel made from stove pipe. The screws are stainless steel 4-40 with LocTite red. There is a screen inside if the nuts should come off, but they have not:

Next, the screws that hold the engine in WILL fall out. They have a floating shoulder bushing and a flanged head screw, but since the bushing can spin there is nothing to prevent the screw from turning. I replaced them with cap screws and LocTited them in:


OK, the steak is done - more after dinner!

 

[Chris-PA]

Then there are the fun mods! The muffler is modded of course. The early Type 1 mufflers are really easy to modify, as the housing is two pieces. The internal baffle got drilled out, and the already large outlet was pried open. Here is a shot with the original baffle:

It was also ported, but it was before I had made a degree wheel so I was mostly winging it. The width of the ports is about 55% of the bore. This old shot of the exhaust is out of focus - I discarded the steel insert:

A better shot of the intake:

The ignition is advanced about 3deg. I tried to measure the port timing later through the spark plug hole and looking down the intake and got (duration):
E=158
I=168
T=115
But I'm not really sure I believe those numbers as it was not the most accurate view. I did not touch the transfers.

EDIT: I measured the numbers more accurately:
E=158
I=168
T=109

 

[Chris-PA]

Then I decided to fit the earlier blue turbo air filter scoop instead of the lame "Super Clean" system put on the later saws. Here is the Super Clean air box inlet:

This got replaced by the Turbo Clean setup, which entailed replacing the carb mount - I used one from an older Poulan 315:


I also ended up using the carb from the 315 - it is the same size Walbro WT (34/64" venturi, the largest of that series), but seemed to run better than the WT529 is came with.

 

[Chris-PA]

So that's what a cheap 46cc saw can do, and what it takes to make one of these reliable. It's actually a very useful tool now, and given the weight it ends up coming out to work quite a bit. It's hard to justify putting a 20" bar on a larger, heavier saw when this runs as it does.

 

[cedarshark]

Good job Chris. I have a pp 4218 in the mail that should be here Monday. This is all interesting stuff. I have a bunch of Stihls but this poulan from a liquidator was too cheap tp pass up. Good to know there are some things to do to prevent future problems.

 

[zogger]

Nice writeup!

 

[stubnail67]

hell yea!!!!!!!!!!!!!!

 

[Chris-PA]

Good job Chris. I have a pp 4218 in the mail that should be here Monday. This is all interesting stuff. I have a bunch of Stihls but this poulan from a liquidator was too cheap tp pass up. Good to know there are some things to do to prevent future problems.

Thanks - your Poulan is a different saw though. It is an evolution of the other plastic clamshell Poulan design, which derived from the A/V version of the Wild Thing. I have an older Craftsman version of that (basically it is a PP260), and they do not have any of the vibration related issues. The A/V system on yours will be different, but even my old Craftsman has a better rear A/V mount design than this 2775 - it's quite strong. It does not run like the 2775 though, but still quite good. Yours will be strato and may run well - I want to port one of those someday.

 

[zogger]

Good sound and that badboy is cuttin!

 

[Chris-PA]

Good sound and that badboy is cuttin!

I forgot to mention that - the saw is loud. And because it likes to rev, the sound has a quite penetrating edge to it. The thing just makes me chuckle when I run it, as it just doesn't seem like it should run as well as it does. There is nothing obviously special about the engine design - dual open transfers and a flat top slug for a piston. But it works.

The 40cc engine in my Husky 142 is the same design, and it really goes too - it has not been ported and has just a muffler mod.

 

[sunfish]

Good stuff!

 

[redfin]

I like the way you think through every detail Chris. Nice job.

 

[woodeneye]

Sweet little tricked out saw. I'll take one.

 

[Chris-PA]

Sweet little tricked out saw. I'll take one.

There's lots of them out there - the 46cc Poulan models with chain brakes are the 2775 and 2900, and the Poulan Pro models are the 295 and 4620. And lots of Craftsman models. It was really pretty impressive with just a muffler mod too.

 

[zogger]

I was thinking of some sort of jig or..something...for taking down the clamshells to get a scosh compression increase. Have to be simple though.

Or maybe I am a tard..didn't Arrowhead do something like this?

 

[CTYank]

Chris, you forget to mention the saw's chip-clearance ability. Clutch cover design, of course.

A bit back I had a Poulan 2150, 35 cc. Could not get it to clog with noodling chips. For a pre-strato non-cat saw it was very clean running. Nothing like the usual noxious 2-stroke exhaust. Must have had very well designed transfer exits.

I'm very pleased with the performance of a $94 PP4218. Excellent A/V and good power. Carb venturi is little larger than 1/4" ID. For reference, a bud who has a 250 Stihl tried it for a few cuts. Said the Stihl came in second for A/V and power. Wanna buy a 250? Cheap?

Some folks here are obsessed with displacement. Misguided IMHO. Focus should be on chain edges. For kicks at GTG last week, I tried a 61 cc Dolly with 24" semi-chisel noodling a solid piece of sugar maple. No challenge. More than adequate displacement w/decent chain.

 

[dougand3]

Chris, good write up and excellent result.
Chris and CTYank: Are the yellow 4218 Poulans as good, build-wise, as your 2775? Here are 2 on CL that I was considering getting to learn on.
http://huntsville.craigslist.org/tls/4576791847.html

 

[LegDeLimber]

I lose track of who has what. Any chance that you've got some of the pistons and can weigh them for difference??
I always thought my 2900 superclean seemed to run decent, but mostly attributed the difference to the other peoples badly maintained chains.
Do you recall what carb is on your 4620? I believe this 2900 had a wt-285 on it.
Hate to say it but I've let things here get into a scrambled state over the last few years.

 

[Echoboy86]

Awesome write up Chris!!! I've been thinking about doing one on my Jonsered 2040 turbo. Its had the works; ported, welded pop-up, 6 degree timing advance and WT- 657 carb (thinned throttle & choke shafts and the casting flash as been removed,) the muffler is now just a hollow can with a 5/8 diameter pipe outlet.

It normally wears a 13" bar and 8 pin rim, its a limbing machine!!!!
last time I tached it in the cut it was pulling 11'700 !!!!

I absolutely love it!!!