Nik's Poulan Thread
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Note that all my dimensions are given in inches, lol! Good info from Tim too.
Yes sir, definitely pull the cylinder off, then you can tell if the crank is actually centered & which bearing (if not both) need adjusted inward.
I use 0.009” thick plastic tabs, cut in the shape of horseshoes to set the total play at about 0.020”. Tim sets them a little tighter than I do.
Insert one on each side between the brass thrust & the crank. Pull them out when you’re done. The idea came from the Homelite Super Duper 2’s saws service manual.
New brass thrusts are 0.101” thick, I just measured a couple.
When you start tapping the bearings inwards, go easy as the brass thrusts can be cracked &/or broken.
I think this one was busted by an &%*$# that didn’t hold the flywheel up when he bashed the crank snout to relieve the taper fit. The PTO side is the busted thrust shown below.
Remember that the BH108 needle bearings are NOT an interference fit on the shaft, so any force is transferred to the opposite thrust.
Thanks for that very usefull info. So its my crank walking in and on the inside race rather than the races moving oposite directions or bit of both? I've only ever dealt with ball bearing bottom ends before this is new
Yep, crank is walking side to side on the needles, and the thrust is sandwiched between the steel crank throws and the drawn cup bearing inner housing end.
By design, the thrusts should never touch the soft magnesium cases inside, the thrust is installed with the raised “collar” or “shoulder” pointing towards the bearings, to the outsides.
Hope that helps. Once the jug is off, you’ll see the thrusts.
Just inching along Randy. One of my thrust washers on the 4000 had the shoulder worn off and it was stuck on the crankshaft against the throw. No damage to the case thankfully.
The nice thing is these saws are so easy to get apart and back together. Another tip is that if the carb adapter is removed, make sure it goes back on before the cylinder is put in place.
Jethro, there is no case gasket so you will need some gas resistant sealer like Permatex Motoseal, Yamabond, Hondabond or the like.
Sometimes the fuel tank is very hard to remove. It will come out easily when the cases are split. There are also locating dowels front and rear on the cases.
The manual I sent you is very good and worth paying attention to.
One other tip. Don't run the saw with the bar and chain off. The clutch has a habit of exiting on deceleration at high speed. Most of us learned the hard way. Very exciting but annoying if you can't find all the parts. If you need to do testing without the bar and chain, remove the clutch. It's a LH thread so clockwise off.
Pic of a similar bearing
The nice thing is these saws are so easy to get apart and back together. Another tip is that if the carb adapter is removed, make sure it goes back on before the cylinder is put in place.
Jethro, there is no case gasket so you will need some gas resistant sealer like Permatex Motoseal, Yamabond, Hondabond or the like.
Sometimes the fuel tank is very hard to remove. It will come out easily when the cases are split. There are also locating dowels front and rear on the cases.
The manual I sent you is very good and worth paying attention to.
One other tip. Don't run the saw with the bar and chain off. The clutch has a habit of exiting on deceleration at high speed. Most of us learned the hard way. Very exciting but annoying if you can't find all the parts. If you need to do testing without the bar and chain, remove the clutch. It's a LH thread so clockwise off.
Pic of a similar bearing
Indeed!
Most simple to work on & under-appreciated saws. They had some features before its time, I think!
Also you can easily hand cut every gasket & diaphragm on them, not like most others.
Most simple to work on & under-appreciated saws. They had some features before its time, I think!
Also you can easily hand cut every gasket & diaphragm on them, not like most others.
Very simple for sure. A 3400 was the first collector saw I bought. I learned a lot on that saw. Lots of Poulans, Homelites, some Mac's and smatterings of other stuff.
You guys are great thanks heaps I better go pull her apart then. I did cut 5 or 6 cookies with no muffler mod so naturally had to see the difference with a another 5 or 6 and yea a tad richer was needed its slightly louder now still quiet compared to the mac 700 and seems to have a little more balls not a huge difference just a little. They are quite the we grunt box really arnt they am rather impressed you can lean on it and just chugs on through. Soo yea I guess if I want to use it for years to come I'd better bite the bullet.
Thanks again fellas you've been really helpfull
Thanks again fellas you've been really helpfull
26 min later... hope you guys like pics.. the scuffing in the piston is barely feelable if thats a word and the cylinder feels babys bum smooth the crank is waling over on the fly wheel side only and has eatin into the case a little so yeap lucky was definitely time to pull it apart.
redunshee
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That piston doesn't look very good.
Yea it looks real bad on the camera. Can hardly feel anything though. Just been reading and old thread of yours from 09. What are the little red barn pistons like? Ive herd there dodgy
Caught that in the nick of time!
She was heading into the case on the FW side. May want replace both the thrust washers...then reset the bearing(s) in.
Don’t buy a dodgy LRB piston, I’d rather see you clean that original one up & run it. Read that the wrist pin will not interference fit into the heated up con rod, like it is supposed to. New P4000 pistons & rings are very hard to find.
Just in case, measure that piston skirt diameter across the thrust face, about 4mm up from the edge, if you can. The P4000 bore is 1.935”, so if it measures 1.931” or larger, you are good to go.
I wonder if that’s actually a 3700 top end, since the muffler had no right side slit. At least you can still get rings for the 3700s. The P3700 has a 1.875” bore.
Sorry for all the non-metric dimensions...no I’m really not! Lol
She was heading into the case on the FW side. May want replace both the thrust washers...then reset the bearing(s) in.
Don’t buy a dodgy LRB piston, I’d rather see you clean that original one up & run it. Read that the wrist pin will not interference fit into the heated up con rod, like it is supposed to. New P4000 pistons & rings are very hard to find.
Just in case, measure that piston skirt diameter across the thrust face, about 4mm up from the edge, if you can. The P4000 bore is 1.935”, so if it measures 1.931” or larger, you are good to go.
I wonder if that’s actually a 3700 top end, since the muffler had no right side slit. At least you can still get rings for the 3700s. The P3700 has a 1.875” bore.
Sorry for all the non-metric dimensions...no I’m really not! Lol
I saw rings on ebay for it before i hit buy now dam it. Yea sad about the pistons mine will clean up fine theres only 1 little bad spot where its been catching the case cos of the walking crank as fossil said it would. Has anyone here done the 7700 ring job? Fossil also said years back that the Canadian 4000s didn't have the side port in the muffler.
I wish a company would start repoping parts for these and a few other saws and it pisses me off that husky owns the name and could easily make parts again same for the macs too
Definitely Stay Away from LRB pistons, you'll end up needed a cylinder. Screwed up my 3400 top end. Running a 3700 top end now. Second rate parts they have if you ask me.
Steve
Steve
LRB so-called chrome piston for 3400.
Steve
Steve
Nasty man not cool. Why they bother making them? And who is buying them?
Did you check the bore size and is it 1.935
No havent yet will have a look this afternoon hopefully. And maby get the case split. I'm up for seals n thrust washers so far and im contemplating bearings too theve got a little up n down play and then hopefully these 7700 rings on ebay are the thin ones n cut them down. Fossil said its been done before and give that piston some love and then have a nice saw for another 35 years.
Edit.. why are the 7700 rings not sold as a pair? Do they only use one ring?
Edit.. why are the 7700 rings not sold as a pair? Do they only use one ring?
It was said that the fuel tank is difficult to remove, tip of the day, fill it with hot water several times and it will soften up and come right out
Yes it is 1.935
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