Compression is 120 psi on Jonsered 2165; too low?

[ericjeeper]

Take the muffler off

Quit Richarding around and avoiding the true answer.LOL

 

[Ray Bennett]

Hi again...

I just came in from the garage (its about -10c in there).

Cold compression is about 120 psi.

When it wouldn't start on the 3rd pull I got worried and sure enough had forgot to put it in RUN, next pull it started right up.

I let it idle for 10 minutes then ran it at 1/2 throttle or so in bursts then 1/2 sec bursts of full throttle a few times, I don't want it to blow up

I shut it down and then tried the "hold it by the T grip handle and let it go test"

each time it dropped smoothly about 3 inches then a small chug, then a wait of about 2 seconds for a big chug,

then dropped about 3 inches again and repeat, in all it took about 7-9 seconds to go to the bottom of the cord.

I still haven't taken the muffler off...

Ray; I was able to find the two carb adjustments ( L and H)... I assume that I want to back the H screw OUT to richen it up??????

You are correct , counter clockwise is richer, I do not think you need to richen it up, I was making sure you did not lean it up to stop the bog if low compression was the problem, From both your test I assure you new rings will really restore a lot of power to your saw. Without looking at the piston and cylinder I can not be sure if they can be used again. I can tell ya that my 044 had the exact same symptoms and all it needed was rings, I replaced the base gasket cause mine got messed up in the tear down. I ran mine till I did the rebuild and I would not be afraid to run yours either. Keep the carb at stock or slightley richer until the rebuild. never leaner than stock.

 

[Kenora]

I removed the muffler and looked at the piston, it appears perfect, no scratches at all on the exhaust side and I could see through to the far side it it looked good as well...I'll try and post a couple of pictures

 

[Freakingstang]

put a ring in it, take out the base gasket and put some good sealant in it's place and call it a day.

Like others said, it shouldn't bog with the 16".

Your gauge may or may not have the check valve in it, which will give lower compression readings

 

[Ray Bennett]

I removed the muffler and looked at the piston, it appears perfect, no scratches at all on the exhaust side and I could see through to the far side it it looked good as well...I'll try and post a couple of pictures

You are in great shape. Run it till you get time to put a new set of rings in it. Then that saw will really wake up for ya. For about 20 to 30 bucks that saw will be like new. You will want to buy the 5 dollar ring compresser from baileys if you do not allready have one. Makes the job easy.

 

[Kenora]

put a ring in it, take out the base gasket and put some good sealant in it's place and call it a day.

OK I've decided to replace the ring, I appreciate all the advice that has lead me to that decision...I was wondering though about the sealant instead of the base gasket. Did I understand correctly that....I don't use a base gasket, instead I use a good sealant like a form-a-gasket product, and if thats the case is there a recommended one.

 

[Ray Bennett]

I like the extra security of a good base gasket, Some folks here use sealant but I can not tell ya what kind.

 

[slabmaster]

You don't want to run that saw with bad rings too long of you might end up replacing alot more than rings.With compression that low,i would give it a light hone and new set of rings and clean up the carbon while i'm in there and be good to go

 

[slabmaster]

put a ring in it, take out the base gasket and put some good sealant in it's place and call it a day.

OK I've decided to replace the ring, I appreciate all the advice that has lead me to that decision...I was wondering though about the sealant instead of the base gasket. Did I understand correctly that....I don't use a base gasket, instead I use a good sealant like a form-a-gasket product, and if thats the case is there a recommended one.

Taking out the base gasket is a good way to get higher compression,but make sure you check the squish before you run it as that will lower your jug hight.Esspecully if you don't know what was done to the saw already.You don't want the piston kissing the top of the jug

 

[andrethegiant70]

Uh, oh, we've all had this chat before! Either way you work it, you'll get a running saw. My take on it is different still ....if you're going to dig into it, just go ahead and replace the piston...find a good aftermarket job and the saw should run like new for chump change. I have replaced rings only in a few saws. It works just fine, but I have realized that I'm no real judge of how worn the the piston skirt is... it is a type of wear that doesn't show that easily like, for instance, scoring. If the piston does start rattling around in there too much you might break a skirt (thus shlepping a chunk of aluminum into the bottom end), or catch a piston crown on an exhaust port or something. Either way, it gets more expensive pretty quickly, the damage ranging from a shredded cylinder all the way to a detonated crankcase.

Gawd, I sound like a weenie.

 

[Kenora]

Thanks for all the great advice..

I went to fleabay and bought a piston, ring, wrist pin and added a base gasket from poorboyssawsandparts65...

ebay # 270191986874

I have emailed him several times and he was very knowledgeable and friendly..I'll be waiting for the mail now.

When I tear into it I'll remember to take some pictures and post them.

Oh and btw...it was CHEAPER to buy all the stuff on fleabay and ship it than it would have been to walk into the local stealer and buy just the ring and gasket here (in Canada)...whats with that?:angry2:

 

[Kenora]

Well I got my new piston, ring, wrist pin and gasket today

Before I get started I have another question.

Do I have to set or measure the ring end gap or just hope for the best?

Thanks

 

[kurtty]

Well I got my new piston, ring, wrist pin and gasket today

Before I get started I have another question.

Do I have to set or measure the ring end gap or just hope for the best?

Thanks

Nice!
let us know how you make out.
i had to replace the ring in my 371xp a few months back. i dont know what the compression was before i switched it out but now its sitting at about 145psi

 

[Kenora]

Hi again; I had a brain fart and posted the results in another thread (with pictures)

http://www.arboristsite.com/showthread.php?p=955088#post955088

results were not as expected...I still have only 120 psi

 

[PB]

I would check your bearings and seals. Looks like you have bearing break up from the picture but I am not an expert.

Did you re-use the gasket? You could have torn it.

 

[Zodiac45]

Hi again; I had a brain fart and posted the results in another thread (with pictures)

http://www.arboristsite.com/showthread.php?p=955088#post955088

results were not as expected...I still have only 120 psi

Did you hone the cylinder with a ball hone? Generally speaking, you'll pick up compression as the saw breaks in the new rings against the honed cyl. How is the saw running? Still bogging like it did before? Did you ever try the carb tuning suggested?

 

[Kenora]

No I did not hone the cylinder, I had no way to do that and the majority of opinion "seemed" to be that provided there was no damage to the bore (there isn't) that "dropping a new ring" would cure the problem. I went one better (I thought) and added a new piston and ring.
It starts on the 1st pull and seems to run as before. I don't have a log to cut into to test it under load though.
I haven't touched the carb either but I did try to move the H and L adjustments on the side of the carb. NO WAY. They won't move?
Here is a picture of the bore and I added another of the adjustment screws on the carb and THANKS, I APPRECIATE THE ADVICE

 

[PES+]

Have you checked you compression release?

It may have a manual or an automatic release or it may have a plug.

Can you post a pic of the clutch side of the saw with the cover removed?

 

[Kenora]

you bet!

 

[PES+]

Ok

You have a manual compression release.

Take out the release and check the valve in the threaded end for carbon build up and see if it functions correctly.

Use a socket and make sure the sealing washer doesn't get lost when you take out the valve.

Also have you checked your compression gauge with a different saw to verify that it reads reasonably close to reality?

Also what is your elevation above sea level (approx)