Carb question

[Mt.Olive10]

O.k guys, I have a brain wrecker for the saw gurus out there. I bought an older 394xp off an old school logger, brought the saw home and hung a 28" bar on it. The saw was very lazy and since it was my first Husky, initially I used it as an excuse to stay brand loyal to Stihl. And even though I got the saw pretty cheap, I've been knowing this guy for years and sticking it to somebody is just not his nature. But like I said, it was my first Husky and I was reluctant to twist on it because I've never ran one. I did a compression check and saw blew a little over 150psi. Even pulled that funky clutch set up off and made sure the saw didn't have an 8-pin on it because he loves 8-pin sprockets. I ordered a dual port muffler put it on and looking through the exhaust, piston looked great!
Well, when I went to adjust the carb to compensate for the dual port, I found an obvious problem. The hi-speed jet was turned all the way in.........and I mean ALL THE WAY In. I adjusted the carb, same way I do a Stihl and immediately, I could tell a huge difference. Now I didn't run the saw much prior to finding this because I was always disappointed in the performance and determined to find out what was wrong! Now in hind-sight, a carb adjustment should have been the FIRST thing I checked and I know this......... so please don't beat me up about that.
What I need to know from someone who has the knowledge is how in the heck did this saw run at all with that jet closed all the way off. And what do you guys think are the chances that this saw has no lean condition damage. 150-155 p.s.i. on compression reading is that good or bad for this saw. Please chime in.
James

 

[cus_deluxe]

If the piston looks good thenyou lucked out. Carb circuits are not something im a pro at, so i cant answer why it would run, other than that it was getting some fuel on the lo side, enough to start, but not have power.

 

[Mt.Olive10]

It has me stumped completely. It was not like it was a hard-starter or anything. Just lazy as a dog. Ran in the cut too,!

 

[Mauser]

I do not know anything about your Husky, but maybe it has a carb similar to what Echo uses on the 590? I do know that my Echo CS-590 has a carb with a partially fixed high speed jet - even when the screw is completely in, it will run fairly well in most conditions - designed just to protect the saw from idiot twiddlers. But it is a problem way up here in the high mountains, where sometimes it is hard to lean out the saw enough to get best tune.

 

[cuinrearview]

I do not know anything about your Husky, but maybe it has a carb similar to what Echo uses on the 590? I do know that my Echo CS-590 has a carb with a partially fixed high speed jet - even when the screw is completely in, it will run fairly well in most conditions - designed just to protect the saw from idiot twiddlers. But it is a problem way up here in the high mountains, where sometimes it is hard to lean out the saw enough to get best tune.

Are you talking about the adjustment limiters?

 

[Mt.Olive10]

I do not know anything about your Husky, but maybe it has a carb similar to what Echo uses on the 590? I do know that my Echo CS-590 has a carb with a partially fixed high speed jet - even when the screw is completely in, it will run fairly well in most conditions - designed just to protect the saw from idiot twiddlers. But it is a problem way up here in the high mountains, where sometimes it is hard to lean out the saw enough to get best tune.

I won't rule anything out!

 

[HarleyT]

If the piston looks good, and the compression is good, it should be fine.
But I would pop the carb up and take some pics of it, might have a leaky needle, or the metering lever is way out of whack, loose welch plug etc..
I am not familiar with that model, so put up a pic of the adj. screws as well.

 

[Deleted member 117362]

Compression is good for a stock saw.

 

[Mauser]

Are you talking about the adjustment limiters?

No - the 590 uses a different carb than 620, which is the pro version of the same saw. The carb on the CS-590 has what is effectively a "bypass" circuit on the high speed screw that ensures a minimum amount of fuel is still fed to the engine even if someone completely closes the high speed screw.

 

[rd35]

I love this kind of thread because I bet several of us will learn something new! I have never heard of a saw that would run with the H needle run all the way in. Hope some photos come up soon!

 

[rd35]

And as I was typing the above response, Mauser posted a response that taught me something new. I did not know there was a carb design with a minimum feed via bypass on the H needle! Awesome info!

 

[cuinrearview]

I love this kind of thread because I bet several of us will learn something new! I have never heard of a saw that would run with the H needle run all the way in. Hope some photos come up soon!

I spoke with OP a little about this and encouraged him to post. The best part of the story is what the shop guy told him when he picked it up.

 

[Mauser]

And as I was typing the above response, Mauser posted a response that taught me something new. I did not know there was a carb design with a minimum feed via bypass on the H needle! Awesome info!

Here is a direct quote from the Echo service manual for the Echo CS-600P:

"NOTE: When H mixture needle is turned completely clockwise, the engine will continue to run. If engine speed at WOT is above 13,300 rpm, adjust H mixture needle counterclockwise and set maximum engine speed at less than 13,000 rpm."​

 

[Mauser]

Of course, if some monkey has been cranking on those adjustment screws like an idiot, that high speed circuit might not be able to completely close or be properly adjusted, no matter what kind of carb the saw has. There IS a reason why every user manual cautions to only GENTLY close those screws when doing adjustments. In the OP's situation, I would certainly be inspecting the inside of that carb!

 

[Deleted member 117362]

Does your carb have limiters in place? If so, you will be able to run it turned all the way in. A little obvious, so people can only lean out so far.

 

[HarleyT]

I always ask for pics, so everyone can see what we are talking about.

But that is just me.....

 

[Gord404]

Work- owned a lot of those saws, do yourself a favor, if you pull and put a kit in the carb, get a new block gasket that goes between carb and intake block, prone to air leak in that area and the pulse to operate your diaphragm goes through it unlike the 395 that has a boot and a separate pulse line, sounds like you got a great saw there.

 

[rd35]

Does your carb have limiters in place? If so, you will be able to run it turned all the way in. A little obvious, so people can only lean out so far.

Oh okay...I see what you are saying. With those limiters in place, they do stop the adjustment well before the needle actually seats! I think the intention was to prevent a rich condition which is bad for air quality...but they actually stop the operator from making more than one full turn total (either direction) which is not enough rotation to be able to seat that H needle on most carbs.

 

[Mt.Olive10]

O.k. for a little more clarity AND thanks to all you guys for your shared knowledge. EVERY TIME I pick a saw up from this guy, I have to go back and adjust the hi-speed jet because he swears that circuit alone helps the saw to become a fuel miser! He used to own a J-Red dealership in this area and he was an old school pine logger. He puts a darn 8-pin sprocket on everything and he takes 4 saws to a job when people call him to throw trees for them because he believes in "resting" a saw. He's not an idiot, but he has his ways! He sets a saw up to scream in pine and he does not get that a 8 pin in pine is a total different animal than in hardwood. Other than that and the hi-speed quirk he has, this guy can take a basket case saw and make it a runner in no time.
As far as the 394 I got from him, I don't think there are limiters in the carb or anything was wrong with it when I got it, because he was making a living with it and I had to beg him to sell it. Wed is my birthday and we've been getting drenched with rain here in Louisiana so no disrespect to you guys but for the next two days, I won't be getting oil or grease on me anywhere. But after that I WILL get pics and figure out how to post so we can have another go at this discussion. But I know for a fact that this saw is all stock other than the dual port muffler and the after market clutch cover/chain brake assembly that I put on because he don't believe in a chain brake or a chain tensionor. He's approaching 70 and stuck in his ways, but he knows a lot, and running a saw lean as bad of an idea as it IS; he does it and obviously has for a while! Again thanks so much for the info especially chiming in that 150 psi is good for a stock saw. Hard to find 394 P/C these days; just about have to convert to 395.

 

[Mt.Olive10]

Work- owned a lot of those saws, do yourself a favor, if you pull and put a kit in the carb, get a new block gasket that goes between carb and intake block, prone to air leak in that area and the pulse to operate your diaphragm goes through it unlike the 395 that has a boot and a separate pulse line, sounds like you got a great saw there.

Thanks for this tip. I don't plan on pulling this carb, IF I do, I will not put a kit in it myself. I know a guy on EBAY who has just about any carb you want that he rebuilds, sets to factor specs, and sells for real fair prices. I've bought several from him and they ALWAYS run jam up. But I will remember that block gasket that you informed of if/when I cross that bridge.