235 PSI Compression? Jonsered 80

[bulletpruf]

Fellas -

Got a Jonsered 80 several days ago. Spent several hours doing a cleaning and basic triage. Man, this thing was neglected! Prior owner must have been trying to win the title of world's dirtiest saw. Managed to get most of the grime cleaned out, including a few pounds of stuff hiding behind the clutch.

Anyway, as part of the triage, I did a compression test and came up with 235 psi!?!?! Figured something may be screwed up on my gauge so I tried my other one - same reading! It's certainly stout (and has a hellacious kickback), but didn't think compression would be this high. Haven't even seen anything over 200 on any of my saws. Anyone else get readings this high on their vintage Jonsereds?

FYI - this is a cold reading. After the compression test, I primed the carb and got it to pop and then run for a second, but that was it. Haven't changed fuel lines, plug, or fuel filter yet. I'm sure it needs a carb kit, too.

One more question -- the muffler has a heck of a big dent in it. I can probably pull it out a bit with my stud welder and slide puller setup, but I'm also thinking about modding the muffler by doing a muffler mod -- would I have to use a thin cutoff wheel to cut the muffler in half and then weld it back together?

And while I'm at it, does anyone know where I can get a air filter for this saw?

Thanks!

Scott

 

[cbfarmall]

My 81 has sky high compression. Needle was still edging up past 225 when I quit.

I've heard the 82cc models have a bit of a rep for high compression.

Chris B.

 

[HarleyT]

Is there a buildup of carbon in the combustion chamber?

 

[Cantdog]

Is there a buildup of carbon in the combustion chamber?

Probably not.....the 80's had a high dome piston....made to run on early 70's gas....most silver tops will easily pull over 200 if in decent condition.

 

[ChoppyChoppy]

Probably not.....the 80's had a high dome piston....made to run on early 70's gas....most silver tops will easily pull over 200 if in decent condition.

70s gas was very high octane?

 

[Jhenderson]

Many years ago I used to do a little business with Sven Johnson,long time pro saw contestant and chainsaw dealer. His shop was about 7-8 miles from me in Lisbon, Ct. He used to say those 80 models are good saws. Too bad you have to crank it!

 

[Jed1124]

70s gas was very high octane?

Leaded gas

 

[Cantdog]

Leaded gas

Yes......and higher octane too...Sunoco 260 was sold as 98.....had a 69 MGB....first page of the owners manual said to not operate this auto on less than 105....that makes todays Premium 92 seem pretty wimpy....had to run AV gas to meet those requirements

 

[Cantdog]

Many years ago I used to do a little business with Sven Johnson,long time pro saw contestant and chainsaw dealer. His shop was about 7-8 miles from me in Lisbon, Ct. He used to say those 80 models are good saws. Too bad you have to crank it!

Ain't that the truth!!!

 

[ChoppyChoppy]

Leaded gas

Gotcha. I didn't realize leaded gas was around that late. I thought it was banned in the early 70s.

 

[fossil]

Not many knew it but the highest octane gas back then was Texaco Skychief. 104 I think. Not sure why they never marketed it as such.

 

[Jhenderson]

" You can trust your car to the man who wears the star, the big, bright, Texaco star"

 

[fossil]

My father worked for Texaco for a lot of years. Do you guys know those pricks were selling fuel to the U boats in WWII? Shell wasn't much better.

 

[Rockjock]

My father worked for Texaco for a lot of years. Do you guys know those pricks were selling fuel to the U boats in WWII? Shell wasn't much better.

Ford sold engines for tanks, Thompson sold machine guns etc.. War is a business.

 

[1Alpha1]

We had a very small gas station brand out of CA., that sold gas with ratings as high as 109-115 octane.

Can't recall the name of the station though. I'll have to call my brother and ask him.

 

[s sidewall]

Leaded fuel was still around in the 80's, ran it in all our power equipment and outboards.

Steve, Samsung On5 using Tapatalk

 

[bulletpruf]

Is there a buildup of carbon in the combustion chamber?

Good question but I doubt it. I pulled the muffler and the piston looks great; didn't seem to have much buildup on the top.

 

[bulletpruf]

Probably not.....the 80's had a high dome piston....made to run on early 70's gas....most silver tops will easily pull over 200 if in decent condition.

Guess I need to check the compression on the rest of my silver tops. At last count I had 20 and have only checked a few of them...

 

[Stihl 041S]

Ain't that the truth!!!

I believe you told me when I started my 111S I should pull " with conviction......."

 

[bulletpruf]

I believe you told me when I started my 111S I should pull " with conviction......."

If/when you ever get tired of pulling with conviction, I have an ad in the Chainsaw for Sale page, looking to buy/trade for a 111 or 111S...