Nik's Poulan Thread

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redunshee said:
I'm hearing more and more about ring gap and its something I don't even consider. I presume if you get the correct rings you're good to go. Not like a car or truck engine. As far as end play. a little in/out play is fine. A lot of Poulans have some. Its radial play(side to side) you don't want.
Click to expand...

Bob

Even if you get the correct rings your ring gap can be excessive if your cylinder is worn.

You can use a bore micrometer to first check if your cylinder is out of round.

Alternatively, you can check the new installed rings to see if there is an excessive gap. If so, then check your cylinder bore.
 
cjcocn said:
Bob

Even if you get the correct rings your ring gap can be excessive if your cylinder is worn.

You can use a bore micrometer to first check if your cylinder is out of round.

Alternatively, you can check the new installed rings to see if there is an excessive gap. If so, then check your cylinder bore.
Click to expand...

Chris, I don't think I've ever seen ring gap specs anywhere. What you say makes sense, thanks. Now the questions is where do you get the info?
Bob
 
parrisw said:
Sure its important, if your using old rings, its good to check to see if their in spec. If not in spec time to replace.
Click to expand...

See, you learn something every day. Thanks. The question becomes" where are the specs?" As I told Chris, don't recall seeing them anywhere. Is there a general rule of thumb for end gap?
Bob
 
I guess best way to find out is measure a new pair, then a worn pair..... I may still have an old and new set of rings for my C91 Homelite. I'll post if I come up with anything. Perhaps a few more can post and we can come up with some general rule of thumb.....The first time this was ever brought to my attention was after I bought my 026 and took it over to Brad Snellings house. As soon as he heard it run, he said something was wrong. Checked comp and it was poor for that saw. Took jug off, and everything looked fine. Checked ring end gap and said it wa waaaay too much. New piston and rings and the saw runs like a champ. I didn't have to replace the piston but did because I got such a good deal on it. Sorry for the lengthy post.
 
FATGUY said:
I guess best way to find out is measure a new pair, then a worn pair..... I may still have an old and new set of rings for my C91 Homelite. I'll post if I come up with anything. Perhaps a few more can post and we can come up with some general rule of thumb.....The first time this was ever brought to my attention was after I bought my 026 and took it over to Brad Snellings house. As soon as he heard it run, he said something was wrong. Checked comp and it was poor for that saw. Took jug off, and everything looked fine. Checked ring end gap and said it wa waaaay too much. New piston and rings and the saw runs like a champ. I didn't have to replace the piston but did because I got such a good deal on it. Sorry for the lengthy post.
Click to expand...

There may be a general rule of thumb that exists. IIRC, it has to do with cylinder bore and is something along the lines of:

0.00X inches of ring end gap per inch of cylinder bore diameter. So: x.xxx" bore x 0.00x = 0.0xx" ring end gap (rounded up).
Click to expand...
 
ring gap

i am putting new rings in my poulan 4000. they are the thin(.025") type. with the old ring in the cyl. at the bottom i get .106" of gap. with a new ring i get .078" gap. that shows .028" of wear. i measured the locating pin in the piston groove and it is .056" dia.it fills the groove and leaves no room for a ring to notch around it, like they normally do. the rings are square ended, no notching for the locator pin. that .058" alone seems like way too much gap. the pins are about 90 degrees apart. how can this be right? looks like a bad design.
it ran with a squirt of gas when i bought it.
i'm going to put in a thin base gasket. what else can i do?
 
turtle561 said:
i am putting new rings in my poulan 4000. they are the thin(.025") type. with the old ring in the cyl. at the bottom i get .106" of gap. with a new ring i get .078" gap. that shows .028" of wear. i measured the locating pin in the piston groove and it is .056" dia.it fills the groove and leaves no room for a ring to notch around it, like they normally do. the rings are square ended, no notching for the locator pin. that .058" alone seems like way too much gap. the pins are about 90 degrees apart. how can this be right? looks like a bad design.
it ran with a squirt of gas when i bought it.
i'm going to put in a thin base gasket. what else can i do?
Click to expand...

Well, I don't have my 4000 apart so I can't measure. I do have a new 3400 piston and the locating pin is the same .056 diameter. Also all the rings I have 3400, 3700 and old 4000 are all square ended so that 's not an issue. There is quite a bit of room between the pin and ring ends( even on the new piston). Don't worry about the pins being too far apart,. I beleve they are fine. Remember these old POulan CV's won't reach 150 or more lbs compression. Probably because of the ring end gap. They will keep running and running however. Put on the jug, use a good sealant like Dirko HT and let her rip.
 
redunshee

4000 update: it lives! finally got the second ring and buttoned it up as suggested,no base gasket.couldn't find dirko ht but did get some yamabond 4 from a local dealer, holding so far. took the comp. after assembly and got 150 lbs.! you were right, not to worry, thanks.
fired it up and adj. idle, ran til hot then let cool. will do cycles for a tank or so. this has that fresh snap to it when you pull on it, gotta love it. worth all the effort.
is there any way to play with timing on these?
what should the air gap be?i just used a business card.
running 32:1 for the break in, what do you run after break in ?
will retest comp. after some more run time.
thanks for all the help.:clap:
 
turtle561 said:
4000 update: it lives! finally got the second ring and buttoned it up as suggested,no base gasket.couldn't find dirko ht but did get some yamabond 4 from a local dealer, holding so far. took the comp. after assembly and got 150 lbs.! you were right, not to worry, thanks.
fired it up and adj. idle, ran til hot then let cool. will do cycles for a tank or so. this has that fresh snap to it when you pull on it, gotta love it. worth all the effort.
is there any way to play with timing on these?
what should the air gap be?i just used a business card.
running 32:1 for the break in, what do you run after break in ?
will retest comp. after some more run time.
thanks for all the help.:clap:
Click to expand...

air gap 0.010"-0.014"

I imagine that timing can be tinkered with as on any saw. Assuming that there is a woodruff key used, omit the key and replace the flywheel slightly misaligned with the groove (so that the key would not fit if it were used). The flywheel nut will keep the flywheel from spinning.

I am too tired to tell you which way would advance the timing and which way would retard the timing.

I am going to bed now.

'Night all.

:cheers:
 
turtle561 said:
4000 update: it lives! finally got the second ring and buttoned it up as suggested,no base gasket.couldn't find dirko ht but did get some yamabond 4 from a local dealer, holding so far. took the comp. after assembly and got 150 lbs.! you were right, not to worry, thanks.
fired it up and adj. idle, ran til hot then let cool. will do cycles for a tank or so. this has that fresh snap to it when you pull on it, gotta love it. worth all the effort.
is there any way to play with timing on these?
what should the air gap be?i just used a business card.
running 32:1 for the break in, what do you run after break in ?
will retest comp. after some more run time.
thanks for all the help.:clap:
Click to expand...

Chris, covered most of your questions. Good to see you got it going. A business card works well to set air gap. I use 40/1 mix with a good synthetic. 150 comp is real good. Sounds like you got a winner.

Bob
 
turtle561 said:
4000 update: it lives! finally got the second ring and buttoned it up as suggested,no base gasket.couldn't find dirko ht but did get some yamabond 4 from a local dealer, holding so far. took the comp. after assembly and got 150 lbs.! you were right, not to worry, thanks.
fired it up and adj. idle, ran til hot then let cool. will do cycles for a tank or so. this has that fresh snap to it when you pull on it, gotta love it. worth all the effort.
is there any way to play with timing on these?
what should the air gap be?i just used a business card.
running 32:1 for the break in, what do you run after break in ?
will retest comp. after some more run time.
thanks for all the help.:clap:
Click to expand...

congrats on getting another 4000 going!
 
It is not a problem for a 3700 to a 4000 to hit 150 psi and these are the thin ring models that I got these readings on.
 
I have found the 3400 is the one that gets around 135psi, and just about everyone I have seen gets close to those numbers. The 3700-4000 series saws get around 150psi in good shape and sometimes a little more.
 

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