372XP Xtorq tuning and RPM

[stantonizm]

So I’m a noob to tuning chainsaws. I have a 372xp Xtorq that I bought for a big storm cleanup in 2012 or so. I haven’t run it a ton but it should at least be pretty well broken in by now. I decided to tune it and bought a DTI 20K tach, since I don’t really have the experience to do it by ear. With the factory tune it hit ~13.4k WOT with no load.

I read all of the threads I could find and there seemed to be some pretty varied opinions on where it should be at RPM wise. To start, I tuned it to idle at 2800 or so, and run at 13k WOT. I tried it out today in a 20” red oak log. It seemed a little slow and the engine would briefly sound different when it was really working. 4-stroking from being too rich maybe?

I hooked the tach back up to it while in the cut with the bar buried and was getting ~10k RPM. I leaned out the H screw to where it was running 13.3-13.4k no-load, which went to about 12.5k under full load. It seemed to cut really fast set like this, but now I’m afraid I might’ve gone too lean.

Any advice on where I should be? Am I good? Am I gonna blow it up?

 

[Deleted member 117362]

So I’m a noob to tuning chainsaws. I have a 372xp Xtorq that I bought for a big storm cleanup in 2012 or so. I haven’t run it a ton but it should at least be pretty well broken in by now. I decided to tune it and bought a DTI 20K tach, since I don’t really have the experience to do it by ear. With the factory tune it hit ~13.4k WOT with no load.

I read all of the threads I could find and there seemed to be some pretty varied opinions on where it should be at RPM wise. To start, I tuned it to idle at 2800 or so, and run at 13k WOT. I tried it out today in a 20” red oak log. It seemed a little slow and the engine would briefly sound different when it was really working. 4-stroking from being too rich maybe?

I hooked the tach back up to it while in the cut with the bar buried and was getting ~10k RPM. I leaned out the H screw to where it was running 13.3-13.4k no-load, which went to about 12.5k under full load. It seemed to cut really fast set like this, but now I’m afraid I might’ve gone too lean.

Any advice on where I should be? Am I good? Am I gonna blow it up?

Factory specs. 2700 idle, 13,500 max. no load.

 

[giver]

Does it still 4 stroke out of the cut?

 

[stantonizm]

Does it still 4 stroke out of the cut?

To be honest, I can’t really tell. I wish I had taken a video to post.

 

[giver]

To be honest, I can’t really tell. I wish I had taken a video to post.

Did you make sure the air filter was clean and it had fresh gas and a good spark before tuning?

 

[stantonizm]

Did you make sure the air filter was clean and it had fresh gas and a good spark before tuning?

Air filter was clean and the gas was fresh. I didn’t check the spark but it was running fine.

 

[ammoaddict]

To be honest, I can’t really tell. I wish I had taken a video to post.

We're you wearing hearing protection? I can distinguish 4 stroking better with ear muffs. Crazy, but it works for me.

Sent from my Moto G (4) using Tapatalk

 

[giver]

Post a video when you have a moment but I'm sure it's fine as long as it's in the specs Duce posted

 

[huskihl]

It's got a limited coil, no?
I'd start rich and gradually lean it to around 13,5. You can go too lean and hear no noticeable increase in rpm if it's on the limiter.

 

[Westboastfaller]

Factory specs. 2700 idle, 13,500 max. no load.

a know the 371 (non limited coil factory recommendations were 13500 and at sometime with 372 they when 13600.
I think the 372 xtorq is 13300 limited?
Not sure if they started at that in 2010 but I believe they are now.

 

[stantonizm]

I was reading the manual online. I noticed it says the limiter kicks in at 13300 but then the subsequent two mentions say 13600. I wonder if 13300 was a typo? Mine was running 13400 or little more with the factory tune.

 

[Westboastfaller]

It can fluctuate throug 'seasons ' and
Altitude.

Maybe there is a bit of wiggle room? IDK
I don't use tac's

try look at a 2012 manual. wonder if there was a diff? It will say on the coil itself.

 

[Rick Stephens]

It's got a limited coil, no?
I'd start rich and gradually lean it to around 13,5. You can go too lean and hear no noticeable increase in rpm if it's on the limiter.

Pay very careful attention to huskihl's post here. With a limited engine, you won't know when you are too lean based only on RPMs, it takes proper procedure. Set the proper low end, only then richen the top end until you are under 13k. Then carefully ease it up by leaning the high to 13,300-13,500. I would really really really want to know which coil limiter I had so I'd know when I was crossing the too lean line.

 

[stantonizm]

It sounds like I should be pretty good. I set the low end following the instructions and then started the high end too rich and turned the screw clockwise until I was at 13000 RPM. Then today I turned it a little more until it was 13.3k with no load.

 

[homemade]

Tune it in the cut. The only way to know where to set it. I’ve set the needles in the garage for good idling and rev up. But you can’t set high unless your in wood. When it seems like it’s running good in the cut, lift the pressure off the cut and listen for the blurrble of sorts. If it doesn’t blurrble and it screames with no load, your too lean.

 

[stantonizm]

So, if the limit is at 13,500, is that number wide open or under load? Right now unloaded is 13.3k, but 12.5k with the bar buried deep in hardwood.

 

[huskihl]

Tune it in the cut. The only way to know where to set it. I’ve set the needles in the garage for good idling and rev up. But you can’t set high unless your in wood. When it seems like it’s running good in the cut, lift the pressure off the cut and listen for the blurrble of sorts. If it doesn’t blurrble and it screames with no load, your too lean.

With a limited coil, the 4 stroke burble sounds very similar to the limiter. He could be a half turn too lean, lift in the cut, and still get a burble from the limiter

 

[huskihl]

So, if the limit is at 13,500, is that number wide open or under load? Right now unloaded is 13.3k, but 12.5k with the bar buried deep in hardwood.

13,5 would be no load. At 12,5 in the wood, you'd want to make the chain more aggressive so it comes down to around 10k

 

[huskihl]

So, if the limit is at 13,500, is that number wide open or under load? Right now unloaded is 13.3k, but 12.5k with the bar buried deep in hardwood.

13,5 would be no load. At 12,5 in the wood, you'd want to make the chain more aggressive so it comes down to around 10k

 

[homemade]

With a limited coil, the 4 stroke burble sounds very similar to the limiter. He could be a half turn too lean, lift in the cut, and still get a burble from the limiter

True. You have to listen to revs vs blurrble to see if it’s a limited coil blurrble or a correct tune blurrble. It’s based on how fast it gets there. You can feel, hear, sense if it’s headed for a lean race and held back by the coil or if it’s the carb doing its thing.