Nik's Poulan Thread

[3000 FPS]

Bob there are only 3 things you need to have it run. Compression, Fuel, Spark. One of those is missing.

I would go back and double check what is going on. Pull the plug and hold it on top of the cylinder with your hand and then give it a good pull to see what kind of spark you have.

IF You have a good spark I would put the plug back in and pull it over about 6 or 7 times and then pull the plug to see if it is dry, wet, or moist.

If dry then no fuel, If wet then flooded, If moist just right.

Last would be compression. Double check it. Put the gauge on another saw to verify it is ok and then check the one not starting. 120psi is fine.

 

[Acornhill]

Bob there are only 3 things you need to have it run. Compression, Fuel, Spark. One of those is missing.

I would go back and double check what is going on. Pull the plug and hold it on top of the cylinder with your hand and then give it a good pull to see what kind of spark you have.

IF You have a good spark I would put the plug back in and pull it over about 6 or 7 times and then pull the plug to see if it is dry, wet, or moist.

If dry then no fuel, If wet then flooded, If moist just right.

Last would be compression. Double check it. Put the gauge on another saw to verify it is ok and then check the one not starting. 120psi is fine.

My first guess would be spark issues, my second would be fuel related


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[3000 FPS]

Well hopefully we will find out.

 

[PogoInTheWoods]

I'd also double check the flywheel timing (keyway) position and coil air gap while going back over things.

 

[fossil]

Looking forward to the results.

 

[fossil]

Pulled cylinder and did better measurements. Ring gap is .076 and I measured pin diameter at .058 leaving .018 clearance. Couldn’t get the .062 pin measurement. Piston skirt measures 1.808 and crown 1.80. Not quite the 1.810 oem measurement. Cylinder base measured 1.87, wider than the 1.810 spec. Still the base shouldn’t wear that much. Not sure what the measurement above the ports is as I didn’t have a way to measure it. Still wouldn’t start after a new plug.

Unless you are grossly flooding the cylinder I would check the flywheel position first like Steve said and then if that doesn't work try a known good coil to elin=minate that. Because the air density changes under compression, each atmosphere added requires that (at 120 psi it takes about 8 times more voltage to fire the plug than it does outside the saw).

I would still check the flywheel position first to make sure the timing is correct.

You can easily check that by checking the flywheel magnet(s) position at TDC on your 3700 against your 3400 ay TDC.

 

[Hoggwood]

Randy, the Cabers you got were junk why? Junk material or wrong dimensions ?

I know I ended up getting a refund on a set listed for the S25 series as well. Metric rings and the side clearance was excessive IIRC. I still have them and could dig out a measurement. I went with Otto's set of Maytag washer rings as per Randy's advice. Perfect fit. I know the Greek ended up changing his listing after I provided him with an early part number for the rings.

Should probably get out the S25DA and break them in a bit more this spring.

 

[hotshot]

Randy, the Cabers you got were junk why? Junk material or wrong dimensions ?

Yep, like Cory said they were metric. .059” thick. My worn S25 piston ring lands needed all the help they can get to close the side gaps, & those should have been standard .063” thick.

It wouldn’t have bothered me so much if he would have stated that, but the prick didn’t & I had to pay the return postage to Athens.

That’s funny on the part number story, as he still has the hooked rings part number 29391 listed (for the later pinned pistons) & is actually peddling butt ended metric 23485 rings...

 

[hotshot]

Ring gap is .076 and I measured pin diameter at .058 leaving .018 clearance.
Piston skirt measures 1.808 and crown 1.80.
Not quite the 1.810 oem measurement.
Cylinder base measured 1.87, wider than the 1.810 spec. Still the base shouldn’t wear that much.

If piston has the standard 1/16” ring keeper pins, your end gap is OK at 0.013” and it should still make enough compression to run well. Where was the ring located when you measured? Above the transfers? Squared up in the cylinder using the piston top?

1.810” is a 3400 BORE size, so your 1.87” cylinder base measurement is a red flag. The 3800 series uses a 1.880” bore...wtf?

An aluminum bore is prone to wear if ran all it’s life with the air filter flocking gone, but .060” wear at the base is not from running a worn filter. Never seen one worn out that bad, somebody may have tried to hone it or sand it before you got it. I’d get another used 3400 cylinder to use, also measuring its bore first. At least they are still easy to find.

Piston is chromed so expect little to no wear, but thinking that they used less taper than your .008” difference from skirt to top. The skirt should be about 1.807” & the ring area at 1.804” to be reusable.

Sorry that I do not have a new or used 3400 piston & cylinder to compare it to.

 

[heimannm]

I finally manage to spend a little time starting to put the 4900 back together. Just like I planned, I made sure to wait long enough to forget where most of the screws went so it was something like a 3D jigsaw puzzle figuring out where all the pieces fit.

Getting the PTO side seal installed was a real treat, does someone have a secret for that? After the case was together I pressure tested and found a small leak from the O.D. of both seals. I am trying Loctite 290, weeping formula that has worked for me on some 10 Series McCulloch seals in the past. Other options?

Mark

 

[s sidewall]

If piston has the standard 1/16” ring keeper pins, your end gap is OK at 0.013” and it should still make enough compression to run well. Where was the ring located when you measured? Above the transfers? Squared up in the cylinder using the piston top?

1.810” is a 3400 BORE size, so your 1.87” cylinder base measurement is a red flag. The 3800 series uses a 1.880” bore...wtf?

An aluminum bore is prone to wear if ran all it’s life with the air filter flocking gone, but .060” wear at the base is not from running a worn filter. Never seen one worn out that bad, somebody may have tried to hone it or sand it before you got it. I’d get another used 3400 cylinder to use, also measuring its bore first. At least they are still easy to find.

Piston is chromed so expect little to no wear, but thinking that they used less taper than your .008” difference from skirt to top. The skirt should be about 1.807” & the ring area at 1.804” to be reusable.

Sorry that I do not have a new or used 3400 piston & cylinder to compare it to.

Don't the 3400 have a slight taper so the piston/rings can go in without compressing. If measured there, would explain why such a high bore reading.

Steve

 

[Acornhill]

Got a bunch of the wood cut & split using the 415

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[Todd Loosli]

Ok, I checked a 3400 cylinder ,base was 1.8132 ,top was 1.8138, .0006 taper due to wear . New oem ring .079 gap . New piston pin .0622. Hope this helps

 

[hotshot]

There’s an oil pump for the big Poulans, one left out of three for sale on FleaBay, if anybody needs one.. #530010173

And no they’re not mine!

 

[PogoInTheWoods]

After the case was together I pressure tested and found a small leak from the O.D. of both seals. I am trying Loctite 290, weeping formula that has worked for me on some 10 Series McCulloch seals in the past. Other options?

I've made it a habit of using a thin layer of Dirko these days on the OD of all seals before installing..., even the rubberized ones. No leaks. That said, I have on rare occasions experienced minor leaks around bearings. Permatex Green has worked for me there. Ultra low viscosity penetrating formula for 'locking' pre-assembled fasteners and sealing very small spaces. After reading the Loctite 290 info online, it seems like the Permatex may even be a slightly lower viscosity version of the same basic stuff. Needs some time to set up, though..., a good 24hrs. I also used a bit of vacuum to draw it in. That works nicely on the OD of a bearing where there isn't much risk of contaminating adjacent parts. Not sure I'd do the same thing on the OD of a seal where it could possibly get drawn into the bearing, tho.

 

[redunshee]

Don't the 3400 have a slight taper so the piston/rings can go in without compressing. If measured there, would explain why such a high bore reading.

Steve

Had a typo error. Cylinder measure at base was 1.807, not 1.87.

 

[heimannm]

I am not sure how I could put Dirko on the PTO side seal and then install it. I had quite a time working it over the square edge of the shaft when it was almost in the bore already. I suppose if I did it again I would make some kind of tapered sleeve to slip over the shaft first. Why didn't I think of that yesterday?

Mrs. Heimann went to see her cousin today so I was free after church to spend a little time in the shop and finish putting it back together. The Loctite 290 did the trick on the seal leaks, I did notice the base gasket was also weeping some tiny bubbles so I put some Dirko on that and screwed it back together. Not sure how long Dirko is supposed to set up but I was impatient so once I got it all together I went a head and started it. If I work on many more Poulans I might be tempted to start dumping the McCulloch saws.

For Poge, the 4900 flywheel has an insert.



I had one casualty during this project, I broke the choke knob off. I may have to come up with some creative solution.



Searching around I found a decent bar to put on it for testing, actually a large frame McCulloch bar but the tensioner and the oiler line up and I had a spare "S" type adapter to account for the larger slot in the bar. Not a bad set up I suppose.





This saw does not appear to have had a lot of use.



Mark

 

[Acornhill]

I am not sure how I could put Dirko on the PTO side seal and then install it. I had quite a time working it over the square edge of the shaft when it was almost in the bore already. I suppose if I did it again I would make some kind of tapered sleeve to slip over the shaft first. Why didn't I think of that yesterday?

Mrs. Heimann went to see her cousin today so I was free after church to spend a little time in the shop and finish putting it back together. The Loctite 290 did the trick on the seal leaks, I did notice the base gasket was also weeping some tiny bubbles so I put some Dirko on that and screwed it back together. Not sure how long Dirko is supposed to set up but I was impatient so once I got it all together I went a head and started it. If I work on many more Poulans I might be tempted to start dumping the McCulloch saws.

For Poge, the 4900 flywheel has an insert.

View attachment 640334

I had one casualty during this project, I broke the choke knob off. I may have to come up with some creative solution.

View attachment 640335

Searching around I found a decent bar to put on it for testing, actually a large frame McCulloch bar but the tensioner and the oiler line up and I had a spare "S" type adapter to account for the larger slot in the bar. Not a bad set up I suppose.

View attachment 640337

View attachment 640338

This saw does not appear to have had a lot of use.

View attachment 640339

Mark

Bad ass


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[s sidewall]

Fuel lines ok

Steve

 

[s sidewall]

And how in the world did you break the choke knob???

Steve