AGAIN...jonsered CS 2165 acting up!!

[pennsdalerepair]

Well, as I last posted yesterday-thought I had the issue with my CS 2165 solved. When starting cold, it fires right up and idles perfectly. Trigger up the throttle and you think it's fine, until...............it warms up a little, and at high speed it runs roughly despite all attempts at adjusting the high speed screws. Brief history--owned the saw since new about 4 years ago. No problems until two weeks ago when I noticed the sporadic rough high speed and missing at idle.

I have cleaned and rebuilt the carb (Walbro HD), replaced fuel and vent lines, fuel filter, ensured fresh mix always used. Air filter clean.Today, I noticed that while the idle now seems fine, the high speed is still erratic, rough, and occasionally dies under load. Also, the rough running condition is much more pronounced when attempting to cut from the bottom of a log up. Thinking the added load of cutting while the chain is pushing instead of pulling is bogging it down more. I now have a replacement carb coming. Spark plug also new. Frustrated as heck; I have a tri axle load of oak sitting here waiting to be cut and split for winter.

I've been a small engine/farm equipment mechanic for over 35 years and never met something that defies logic as this thing does. Thinking about buying a second saw for backup and am curious as to what everyone here thinks make-wise. I really love the Jonny over past Stihl units I've owned, but now I'm wondering what to purchase...

Thoughts?

Tom

 

[sefh3]

Usually if you have a good idle and the saw gets eratic at high speed, you have a seal leaking. It's allowing you to suck in more air than normal. This will cause your engine to seize. Also, what does your piston look like? Do you have any signs of scoring?

 

[mountainlake]

Time to try a new coil, if it doesn't help you have a spare. Steve

 

[dl5205]

Usually if you have a good idle and the saw gets eratic at high speed, you have a seal leaking. It's allowing you to suck in more air than normal. This will cause your engine to seize. Also, what does your piston look like? Do you have any signs of scoring?

I thought "air leak" when I read your first thread, but didn't reply b/c I thought you had fixed it. Since you will have the muffler loose to vacuum/ pressure check it, now would be a good time to peek at the exhaust side of the piston. Take the decomp valve off and check it by itself first, and plug the hole to do your test.

 

[Great Smokies]

Time to try a new coil, if it doesn't help you have a spare. Steve

Sounds like coil to me, misfire in the top end.

 

[duramax99]

Yah I'd be trying a coil, pretty common on that series of saw.

 

[griffonks]

I think air leak, does the saw run the same when you turn it on its side?

I would vac and pressure test before I bought a coil.

 

[rmh3481]

Sounds like the back bar cut is the tell tale sign. When the mounts stretch, the intake boot stretches. As you reef on the bar making the back cut (top of the bar) the crack opens drawing in air.

 

[pennsdalerepair]

All:

I looked closely at the intake boot and, thinking of an air leak, sprayed carb cleaner around the area to see if the running condition improved. No change. If the crank seals were bad, my experience has shown that the engine would be hard starting, if at all. Have not pulled the muffler or comp release valve as yet to inspect piston. This whole saga started after saw was sitting for a few months. Coil spark is bright blue. With all the fuel issues out there and this crap they call gasoline, I'm still leaning toward the carb main circuit being messed up.

I really appreciate the feedback...keep it coming. Any thoughts on the purchase of a backup saw?

Tom

 

[Great Smokies]

Second saw, Dolmar 6400. Beast.

 

[ncfarmboy]

Second saw, Dolmar 6400. Beast.

+1 or a new PS6100.
Shep

 

[Big_Wood]

Sounds like the back bar cut is the tell tale sign. When the mounts stretch, the intake boot stretches. As you reef on the bar making the back cut (top of the bar) the crack opens drawing in air.

On the husky's this stretching you speak of in the intake boot is non existant. Yer talking about the stihls. Stihl carbs are mounted in the air box above the fuel tank ( like a husky ) but the husky's have an over hang on the case which the carb is secured too. The stihls are secured to the tank having the boot go across from the air box to the cylinder which allows stretching if the mounts are shot.

 

[Big_Wood]

I have this feeling it's the carb also but that only because i had a similar issue last week when i built a 365sp. I knew i wasn't gonna keep the saw so i wanted to use a zama carb i had from an older 365. I try to save my walbro's. anyways that saw had the sane issue as yours. Cleaned the carb twice thinking maybe i missed something but nope. Needle adjustments did nothing. Whether the high speed was 7/8's of a turn out or 4 turns out it would still run exactly the same. Threw one of the walbro's from my stash on there and it runs like new. I have actually learned to hate zama's because of this. It isn't the first time i've had the same issue with a zama carb. Never had these issues with a walbro but you may very well be. It's hard to say whether it's the coil or carb in your case though. Blue spark doesn't always mean it'll run good at high rpm. Some coils end up being affected by heat also which could be why you have your issue when it's warm.

 

[dl5205]

It takes Very Little effort to vacuum/ pressure check the decomp valve. I wish I had known to do that First on my 372.

 

[sunfish]

I'd still be leaning toward carb issues myself and would want to try a diff carb next. But a vac/pressure test is in order just to rule out a leak..

As far as a backup up saw, I would stay with Jred, or get a Husky. No need to drop the brand because of one one freak issue like this...

 

[RedFir Down]

What Walbro HD carb is it?

 

[wyk]

On the husky's this stretching you speak of in the intake boot is non existant. Yer talking about the stihls. Stihl carbs are mounted in the air box above the fuel tank ( like a husky ) but the husky's have an over hang on the case which the carb is secured too. The stihls are secured to the tank having the boot go across from the air box to the cylinder which allows stretching if the mounts are shot.

My JRed has a plastic intake boot instead of the "EPA" style rubber slide on and clamp the 372's have. Perhaps he has a leak in it.

 

[Termite]

When you did the carb did you pull the aluminum cup and replace the screen under it. If it is not open it will starve for full at WOT. I learned the hard way. Use the correct size bottom tap for extraction.
Sometimes a fine lint covers this screen and can be burnt off with a little heat .

 

[pennsdalerepair]

Update to everyone...

Pulled most of the saw down first thing this morning. Decomp vlv--clean and functioning properly. Compression--great. Cyl walls and piston--not a mark. Exhaust port--wide open and clean. I'm anxiously waiting for the new carb to arrive....current carb is a Walbro HD-12B. Not a fan of Zama carbs either. I don't rebuild them anymore--simply replace them as it's cheaper for the customer.

After reassembling the saw today, I started it and it has the miss and erratic running right from the cold start. I'm really thinking it's the carb...will keep you posted. Thanks to all for your input--I do plan on purchasing a second Jonny--not sure which model yet, though...

Tom

 

[Big_Wood]

Update to everyone...

Pulled most of the saw down first thing this morning. Decomp vlv--clean and functioning properly. Compression--great. Cyl walls and piston--not a mark. Exhaust port--wide open and clean. I'm anxiously waiting for the new carb to arrive....current carb is a Walbro HD-12B. Not a fan of Zama carbs either. I don't rebuild them anymore--simply replace them as it's cheaper for the customer.

After reassembling the saw today, I started it and it has the miss and erratic running right from the cold start. I'm really thinking it's the carb...will keep you posted. Thanks to all for your input--I do plan on purchasing a second Jonny--not sure which model yet, though...

Tom

have you ever heard an electrical misfire? lean misfire? if so which one does it sound like. I have seen plug wires worn and arcing off cylinder fins many time. damn this is just one of those things where I wish I was there. hard to diagnose over the net. just to many variables. i'm sure it is an easy fix though. if yer getting an actual misfire I will have to turn my vote to something electrical because saws will generally not run before they go lean enough to misfire. if you google testing the coil in that particular saw you may find info on testing with a multimeter. cheaper then buying a coil just to try it. i'm currently looking out for one of those coils for another saw i'm building but if I had an extra i'd send you one