Unorthodox engineering/engine building

Arborist Forum

Help Support Arborist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Junkwrencher

Junkwrencher AKA 2Bears AKA Missedshot
Joined
Nov 8, 2007
Messages
172
Reaction score
45
Location
Middle Tennessee
I read the thread about "THALL'S 262XP REBUILDED'' and really enjoyed it.I notice a trend toward increasing compression, assembling engines without cylinder gaskets, pistion port timing, indexing ignitions, and I know it works and have seen the results.
I briefly discussed some of my ideas in a thread would like to question some of this.Before I do, I realize some of you will chime in and say "BOY, DON'T YOU KNOW NUTHIN' BOUT' BUILDIN' ENGINES? And I'll get schooled and maybe slapped around a little.
Here goes, in rebuilding engines I've had to do things most of you guys wouldn't do, engine abominations, I've put stuff together most of you wouldn't bother doing because it wouldn't work.I'll list some examples.I buy saws in mass from loggers, saw-shops, junkyards, sort through it consolidate models, sell off what I don't need or use.I'm not talking about one or ten saws, truck loads of saws.I bought three truck loads on one occation.Having a budget that looks like a roller coaster I do this you're not supposed to do.
I "put together" a 262xp for a customer for a loaner while I did some warranty work on his 394xp some years ago.The crankcase had a hole in the very bottom the measured size of six millimeters.I cleaned everything up the best I could, installed the best used piston and ring I had and I'll see what happens.I fired the saw, it actuallly starts on the second pull and as we would expect its' overrunning, I back the Idle adjustment all the way out which effectively cuts off the air through the venturi, still revving too high I richen the low-speed jet until the chain stops on a new Husqvarna "FARM TOUGH" bar 20" with 72 drive links of single-drag Oregon 3/8 chain.I Tac-Tune the high speed jet to 13,500 no load and put it in a hickory test log outside the garage and make several cuts.I let off the throttle and it continues to idle unexpectedly, I put the saw back on the tach and it stays at 13-13,500 no load.
"Buddy" is cutting pine on a clear-cut pre-doz job and stays over there for two months.He calls one night and says that 262 is roaring like the crank-bearings are about to go and I told him to bring it by.It once again is overrunning, I richen the carb again, high and low, send him on his way.I finished with his saw 15 gallons of fuel later for the 262xp! The crank-bearings are really loud.
The saw was disassembled and rebuilt correctly with all new gaskets, bearings, piston and ring, filters, plug, etc..I sold it for $200 cash to a logger who wanted it for a trim saw.The next day it cut timber paying for itself and a new 372xp which he never started, the "trim saw" did all the work.
What about a stuck Husqvarna 66?Same guy named "Buddy", he was really hard on that 394, needed a "loaner" so I went to the pile and found a 66 that was complete except for a cylinder cover, it was stuck and had been outside in the rain for at least two years, I pulled the plug and poured in some "liquid innards" most of you will recognize it as Kroll.
The next day I pulled the starter cover and started working the fly-wheel back and forth till she broke loose, I then poured in some clean motor oil and hooked up an electric drill to the crankshaft and spun it for five minutes, dumpted the oil and put the same plug back in, gased it up and installed a new bar and chain on it and it fired easy, ran strong, made Buddy a good loaner.I sold the saw "as is" and it has been in for normal service on two occasions and continues to run today.
Last one, Shindaiwa 488, locked up, straight gas victim,I acid washed the cylinder to find a long score mark running the full legnth of the cylinder wall, the piston is badly scored also, both rings stuck, the only replacement parts in the shop are a set of rings and an optional high-stack "breather", three cylinder gaskets, a really good friend who is a big Shinny fan asks me for a saw.
I clean up the piston by hand with a fine file, clean the ring grooves, install the new rings on the old piston,slid the scored cylinder down on top of three cylinder gaskets and torqued the cylinder bolts.Looking through the exhaust port I rotated the crank and the piston did not snag, hang, so I assembled everything else up to the carb, I replaced it with one off a 695 which is a 69cc saw, the 488 is a 48cc.
This carb doesn't have an idle screw so I bent the throttle plate until it idled at 1 1/4 turn out from a light seat on the low side, installed the high-rise breather and tuned the high side in the hickory with a new 16" .325 chain to what I think is 12K rpm.This saw had loads of grunt for a little saw and I couldn't bog it out!
In the extra head gaskets I lowered the compression but the volume increased, installing the big carb and larger breather helped too, did the groove in the cylinder act as an extra exhaust port?
And how about the mill oiler I installed on my Poulan 3800 because it wasn't getting enough oil cutting firewood?
 
Last edited:
par·a·graph /ˈpærəˌgræf, -ˌgrɑf/ Pronunciation Key - Show Spelled Pronunciation[par-uh-graf, -grahf] Pronunciation Key - Show IPA Pronunciation
–noun
1. a distinct portion of written or printed matter dealing with a particular idea, usually beginning with an indentation on a new line.



:hmm3grin2orange: :hmm3grin2orange:




I think my eyeballs are bleeding :D
 
I read the thread about "THALL'S 262XP REBUILDED'' and really enjoyed it. I notice a trend toward increasing compression, assembling engines without cylinder gaskets, pistion port timing, indexing ignitions, and I know it works and have seen the results. I briefly discussed some of my ideas in a thread would like to question some of this.

Before I do, I realize some of you will chime in and say "BOY, DON'T YOU KNOW NUTHIN' BOUT' BUILDIN' ENGINES? And I'll get schooled and maybe slapped around a little. Here goes, in rebuilding engines I've had to do things most of you guys wouldn't do, engine abominations, I've put stuff together most of you wouldn't bother doing because it wouldn't work.

I'll list some examples. I buy saws in mass from loggers, saw-shops, junkyards, sort through it consolidate models, sell off what I don't need or use. I'm not talking about one or ten saws, truck loads of saws. I bought three truck loads on one occation. Having a budget that looks like a roller coaster I do this you're not supposed to do.

I "put together" a 262xp for a customer for a loaner while I did some warranty work on his 394xp some years ago. The crankcase had a hole in the very bottom the measured size of six millimeters. I cleaned everything up the best I could, installed the best used piston and ring I had and I'll see what happens.

I fired the saw, it actuallly starts on the second pull and as we would expect its' overrunning, I back the Idle adjustment all the way out which effectively cuts off the air through the venturi, still revving too high I richen the low-speed jet until the chain stops on a new Husqvarna "FARM TOUGH" bar 20" with 72 drive links of single-drag Oregon 3/8 chain. I Tac-Tune the high speed jet to 13,500 no load and put it in a hickory test log outside the garage and make several cuts. I let off the throttle and it continues to idle unexpectedly, I put the saw back on the tach and it stays at 13-13,500 no load.

"Buddy" is cutting pine on a clear-cut pre-doz job and stays over there for two months. He calls one night and says that 262 is roaring like the crank-bearings are about to go and I told him to bring it by. It once again is overrunning, I richen the carb again, high and low, send him on his way. I finished with his saw 15 gallons of fuel later for the 262xp! The crank-bearings are really loud.

The saw was disassembled and rebuilt correctly with all new gaskets, bearings, piston and ring, filters, plug, etc.. I sold it for $200 cash to a logger who wanted it for a trim saw. The next day it cut timber paying for itself and a new 372xp which he never started, the "trim saw" did all the work.

What about a stuck Husqvarna 66? Same guy named "Buddy", he was really hard on that 394, needed a "loaner" so I went to the pile and found a 66 that was complete except for a cylinder cover, it was stuck and had been outside in the rain for at least two years, I pulled the plug and poured in some "liquid innards" most of you will recognize it as Kroll. The next day I pulled the starter cover and started working the fly-wheel back and forth till she broke loose, I then poured in some clean motor oil and hooked up an electric to the crankshaft and spun it for five minutes, dumpted the oil and put the same plug back in, gased it up and stalled a new bar and chain on it and it fired easy, ran strong, made Buddy a good loaner. I sold the saw "as is" and it has been in for normal service on two occasions and continues to today.

Last one, Shindaiwa 488, locked up, straight gas victim,I acid washed the cylinder to find a long score mark running the full legnth of the cylinder wall, the piston is badly scored also, both rings stuck, the only replacement parts in the shop are a set of rings and an optional high-stack "breather", three cylinder gaskets, a really good friend who is a big Shinny fan asks me for a saw.

I clean up the piston by hand with a fine file, clean the ring grooves, install the new rings on the old piston,slid the scored cylinder down on top of three cylinder gaskets and torqued the cylinder bolts. Looking through the exhaust port I rotated the crank and the piston did not snag, hang, so I assembled everything else up to the carb, I replaced it with one off a 695 which is a 69cc saw, the 488 is a 48cc. This carb doesn't have an idle screw so I bent the throttle plate until it idled at 1 1/4 turn out from a light seat on the low side, installed the high-rise breather and tuned the high side in the hickory with a new 16" .325 chain to what I think is 12K rpm.

This saw had loads of grunt for a little saw and I couldn't bog it out! In the extra head gaskets I lowered the compression but the volume increased, installing the big carb and larger breather helped too, did the groove in the cylinder act as an extra exhaust port? And how about the mill oiler I installed on my Poulan 3800 because it wasn't getting enough oil cutting firewood?


Tried to break it up some, didnt bother touching the grammar or the spelling. :hmm3grin2orange:
 
Ribbing/roasting

So that's what those english and journalism classes were for! Are my shoes untied? Is my shirt-tail untucked? Is something on my shirt? How 'bout my nose, anything hanging out of it?
 
that will be the difference between a mechanic and a fitter then
i fixed a ford gearbox years ago it had a small hole i drilled it larger hammered in a penny and coated it in jb weld 3 years later it was still going
asked my "mechanic" mate what he would do first he thought he would fit a new casing but at £70 an hour it would be cheaper to fin a new gearbox!!!!
 
Back in the day (yeah I'm old enough to say that) I fixed a cracked block on a 440Magnum by drilling small holes the length of the crack and one at each end to keep it from speading.

Then put short sheet metal screws in and welded them together.Never leaked after that.
 
Back in the day (yeah I'm old enough to say that) I fixed a cracked block on a 440Magnum by drilling small holes the length of the crack and one at each end to keep it from speading.

Then put short sheet metal screws in and welded them together.Never leaked after that.

That's slick...

"Stop holes" I learned about on my first (& only) liquid cooled dirt-bike, '85 KTM 350. It somehow broke a cylinder base stud or two... and made the most awful "whackawhackawhack!" noise, as the jug took a right smart whackin' from the con-rod. Tried to turn itself into a 1.5 stroke! The only damage was a slight crack in the very bottom of the sleeve (iron liner) going up maybe 17mm. A stop hole, and a little sandpaper & stone work (plus a base gasket and studs/nuts) got me back in the saddle.

Necessity is the mother of invention, and improvisation is the mother of all disasters... but sometimes ya have to wing it.
 
Rebuild questions

Junkwrencher-I have a Jonny 920 and want to rebuild it to get more compression. It also pulls hard because the chain won't stop at idle. How do I fix that? Anyway, I would like to put in new rings. How do I know what rings to get/how do I know if I need to hone the cylinders/how do I know if I hone them, how much to take off, etc...
Thanks
 
response to ericlane

Your chain keeps turning because your clutch spring/s are bad or your clutch has exploded and jammed inside the drum.As far as a rebuild, find a Jonsereds dealer or figure out which Husqvarna is or may be the equivilent.As for the cylinder bore, that depends on who you ask, if I can get the walls to slick up with emery cloth I don't hone, otherwise, get a hone from Baileys and do a search on cylinder reconditioning/honing....
 

Latest posts

Back
Top