Chainsaw Repair

How To Basics - Carb Fixes + Mods - IPL and Service Manuals => How To Basics and Fixes => Topic started by: Giles on May 06, 2015, 09:35:46 pm

Title: The change in Chainsaws and other small engines.
Post by: Giles on May 06, 2015, 09:35:46 pm
I have worked on small engines for over fifty years, and I have seen a lot of changes.
The last chainsaw that I bought new, was a 1980 Husqvarna 40. I wore out three bars and countless chains and rebuilt the carburetor two or three times. It still runs like new and engine hasn't been into.
The point I am trying to discuss is the fact that I never had to periodically adjust the carburetor. Each time I rebuilt/cleaned the carb, I would just return the screws to where they were.
I found this to be true with lawnmowers as well.
With any of todays saws, even a change in brands of gasoline or oil will likely change the carb settings.
I am referring to muffler and carb modded saws and other small engines, but more so with chainsaws.
Do any of you have the same memories and why do you think we have to really watch carb settings today?
Title: Re: The change in Chainsaws and other small engines.
Post by: 660magnum on May 06, 2015, 11:01:05 pm
I had an old Homelite 150XL from 1975 until 1997 and I don't remember ever having to adjust the needles.

I have Husqvarna 357XP and every time I get it out I have to go through the ritual of setting the needles.

A few weeks ago I got out my Stihl 026 PRO which has been ported and muffler modded and had to fiddle with the needles to get them reset and balanced out from being extremely rich. The last time I run it the temperature was about the same but it had Klotz oil before and now has Pennzoil so that was probably it.

I ran a 371XP several times since the snow melted and didn't have to change the needle valves but it is stock.

I have a couple of AT saws and they don't have needle valves.
Title: Re: The change in Chainsaws and other small engines.
Post by: Giles on May 06, 2015, 11:11:42 pm
I should have mentioned that I have adjusted the carb many times on the 40, in the last few years.
I think it is in the quality of the gasoline we get today. Just wanted some other opinions.
Old Craftsman (roper) 3.7 I bought new in about 1980, would barely run until I adjusted the carb, then ran excellent.
It had been stored dry for over eight years.
Title: Re: The change in Chainsaws and other small engines.
Post by: aclarke on May 06, 2015, 11:53:24 pm
Oxygenated fuels/alcohol added fuels will cause variations. We get different formulation during the year which can cause tuning issues
Title: Re: The change in Chainsaws and other small engines.
Post by: JohnG28 on May 16, 2015, 09:06:10 am
I am sure the fuel has some to do with it. The additives chance from winter to summer I believe and you never can really tell the ethanol content, even if supposedly E0. Along with that I also would guess with manufacturing tolerances much tighter than in years past that things like carb adjustments are probably a lot more precise than older models which could make them more sensitive to variations. My guess anyway.