Quick Carb Adjustment Question

[Campin' Cutter]

Hi,
Working on tuning the carb on my 288 with my tac, and am having trouble getting the saw to reach max no load RPM. The saw will start, idle, and accelerate beautifully, but I'm topping out at 11,800 and my service manual says I should be at 12,500. If I lean out the high past 11,800 the saw starves for fuel and RPMS drop by several thousand. So, my question: I'm thinking that leaning out the low screw a little, then readjusting the high screw, will probably get me where I want to be. I'd mess with it more, but it's dark here and the neighbors don't seem to like eating dinner to the sounds of a chainsaw. Anyway, am I on the right track here, or what would you advise? My current needle settings are L 1.25 out and H 3/4 or so out. Thanks!

 

[huskihl]

Is the saw all original or at least OEM? If it has an aftermarket cylinder on it, that might prevent full rpm

 

[lone wolf]

Hi,
Working on tuning the carb on my 288 with my tac, and am having trouble getting the saw to reach max no load RPM. The saw will start, idle, and accelerate beautifully, but I'm topping out at 11,800 and my service manual says I should be at 12,500. If I lean out the high past 11,800 the saw starves for fuel and RPMS drop by several thousand. So, my question: I'm thinking that leaning out the low screw a little, then readjusting the high screw, will probably get me where I want to be. I'd mess with it more, but it's dark here and the neighbors don't seem to like eating dinner to the sounds of a chainsaw. Anyway, am I on the right track here, or what would you advise? My current needle settings are L 1.25 out and H 3/4 or so out. Thanks!

Thats about where my old 288 would tune at . Just leave it be.

 

[Campin' Cutter]

Is the saw all original or at least OEM? If it has an aftermarket cylinder on it, that might prevent full rpm

The saw is new to me as of today (bought off another member here) who indicated everything is oem except the muffler. Was told it was recently rebuilt with a NOS OEM piston and cylinder. My 2 stroke compression tester says 150 for compression. Was also told that all seals/gaskets/rubber had been replaced, which I believe as it looks that way and I don't have any reason not to believe the seller (who was super nice and a pleasure to work with in every way). Just never run into this specific issue before when using a tac.

 

[Campin' Cutter]

Thats about where my old 288 would tune at . Just leave it be.

Perfect, sounds like everything is good to go then. I appreciate the response!

 

[lone wolf]

Perfect, sounds like everything is good to go then. I appreciate the response!

Dont want to lean it out too much anyway.

 

[Campin' Cutter]

Dont want to lean it out too much anyway.

Yeah for sure. That's why I have the tac, I don't trust myself to set it properly by ear. I suppose a little under book max is good insurance.

 

[J D]

Is it still 4-stroking at 11,800 RPM?
Are you sure your tach is accurate?
I'd assume someone with the know how to rebuild it would've tuned it before sending it out... what was it set at when you received it?

 

[Campin' Cutter]

Is it still 4-stroking at 11,800 RPM?
Are you sure your tach is accurate?
I'd assume someone with the know how to rebuild it would've tuned it before sending it out... what was it set at when you received it?

Not sure about the 4 stroking, my ears have trouble hearing the difference. Tach is for sure good, when I rebuilt the top end on my 262xp I used it to set the high side and it was accurate. I didn't check the 288 with the tach before adjusting, but I could tell from the sound that it was running rich and therefore slow. It sounds good at 11,800, just not sure about the 4 stroking. I'll probably just leave it and see how it preforms this weekend.

 

[ammoaddict]

Not sure about the 4 stroking, my ears have trouble hearing the difference. Tach is for sure good, when I rebuilt the top end on my 262xp I used it to set the high side and it was accurate. I didn't check the 288 with the tach before adjusting, but I could tell from the sound that it was running rich and therefore slow. It sounds good at 11,800, just not sure about the 4 stroking. I'll probably just leave it and see how it preforms this weekend.

I can actually hear the difference better with muffs on. Try it.

Sent from my moto g(7) power using Tapatalk

 

[Campin' Cutter]

I can actually hear the difference better with muffs on. Try it.

Sent from my moto g(7) power using Tapatalk

I'll give that a try! Thanks for the tip

 

[HarleyT]

If you are toying with it again. Take off the air filter then adjust, see if that changes anything on the very top rpm. But I always err on the rich side.

And before anyone hops in, put the air filter back on and re-adjust before using the saw....
I hate to say it, but someone would likely chime in something about that.

 

[huskihl]

I'll give that a try! Thanks for the tip

Or take a video of it. It’s quite a bit easier to hear it recorded from 15-20’ away

 

[Campin' Cutter]

I'll be messing with it again tomorrow and this weekend. Have some time after work tomorrow to adjust the carb a bit more, I don't have it quite where I want it yet. There's a slight hesitation on acceleration so I'm going to open the low jet just a touch, then work on the high side again. I'll try the ear muffs for the 4 stroking once I get in the right rpm range with the tach. Will try the video suggestion as well if it comes to that.

 

[J D]

If you are toying with it again. Take off the air filter then adjust, see if that changes anything on the very top rpm. But I always err on the rich side.

And before anyone hops in, put the air filter back on and re-adjust before using the saw....
I hate to say it, but someone would likely chime in something about that.

& for the newer saws (with "air injection") you need to tune with the top cover on too or it will be lean when the cover goes on