HS151A Rebuild On My SXL-925

[edju1958]

Hello,I had to rebuild the carb in my SXL-925 today.I had the saw out last week cutting & I couldn't keep it idling for nothing.Finally the recoil locked up on me,so I had to quit using it.I pulled the recoil & one loop of rope had looped "out of turn" if that makes any sense.I tightened up the play in the rope,so hopefully that takes care of the recoil issue.I pulled the pump cover to see what I was in for & found the diaphragm to be like cardboard.That prompted me to put anew kit in it today.The screen was loaded full of junk,but the rest of the carb was spotless.My question here is what shouid I start the hi speed needle at?I've got it set at 3/4 turn out.Previously it was set at 1/2 turn out.I've never touched the settings on the saw only because I've heard that the hi speed is factory set & shouldn't be messed with.I think 1/2 turn out is a bit on the lean side though.The lo was set at 1 3/4 turns out,which seems to be on the rich side.I set it at 1 turn out.

[Clasec]

Mar 11, 2020 19:47:12 GMT -5 edju1958 said:

Hello,I had to rebuild the carb in my SXL-925 today.I had the saw out last week cutting & I couldn't keep it idling for nothing.Finally the recoil locked up on me,so I had to quit using it.I pulled the recoil & one loop of rope had looped "out of turn" if that makes any sense.I tightened up the play in the rope,so hopefully that takes care of the recoil issue.I pulled the pump cover to see what I was in for & found the diaphragm to be like cardboard.That prompted me to put anew kit in it today.The screen was loaded full of junk,but the rest of the carb was spotless.My question here is what shouid I start the hi speed needle at?I've got it set at 3/4 turn out.Previously it was set at 1/2 turn out.I've never touched the settings on the saw only because I've heard that the hi speed is factory set & shouldn't be messed with.I think 1/2 turn out is a bit on the lean side though.The lo was set at 1 3/4 turns out,which seems to be on the rich side.I set it at 1 turn out.

Here you go ED.                                  925 carb adjustment by Clasec, on Flickr

[edju1958]

Thank you Charles!

[alec]

When I adjusted mine recently I ended up about 1/2 out on the hi.

[edju1958]

Well obviously the carb wasn't the issue,the saw still runs like crap.I don't know what the problem is & I don't know where to start.I had a Stihl 029 that had similar problems about 10 yrs.ago.That turned out to be a bad crank bearing.How would I tell if the crank bearing is bad without tearing the saw down?

[onlyhomelites]

Well you can't do much other than "lift" the flywheel and clutch. If you get more than a tiny smidge of movement, you have a worn bearing. But a bearing would have to be really worn; not common on the 925.

Can you expand a bit on how it's running? Does it rev out okay? No idle typically is a plugged low speed passage or flooding from a leaking fuel inlet needle, a bad reed valve (should be lots of spitback) or an improper ignition gap. The only part of the 925 ignition that's adjustable is the generator coil, but it can be gapped. Could also be a failed lead from the pickup module under the flywheel...those leads are famous for cracking. An ohmmeter would pin that down quickly.

[edju1958]

Mar 15, 2020 0:03:03 GMT -5 onlyhomelites said:

Well you can't do much other than "lift" the flywheel and clutch. If you get more than a tiny smidge of movement, you have a worn bearing. But a bearing would have to be really worn; not common on the 925.

Can you expand a bit on how it's running? Does it rev out okay? No idle typically is a plugged low speed passage or flooding from a leaking fuel inlet needle, a bad reed valve (should be lots of spitback) or an improper ignition gap. The only part of the 925 ignition that's adjustable is the generator coil, but it can be gapped. Could also be a failed lead from the pickup module under the flywheel...those leads are famous for cracking. An ohmmeter would pin that down quickly.

That's the only way it'll run is by revving up.It runs great at high speed,just won't idle worth a damn.There's no spit back by the carb.It almost acts like it's starving for fuel on the low end.It's not flooding at all,as a matter of fact after stalling out when I go to restart it I have to put the choke on.I'll try running some Seafoam in the fuel & then let it set for a couple of days & then try it again & see if there's a difference.I really need this muscle saw to cut a giant ash tree.Last yr.when we dropped the tree we had to come in from both sides with a 28 in.bar & chain.

[onlyhomelites]

You know the high speed nozzle is also supposed to act as a check valve in that Tilly...if it has failed, the engine pulses would disrupt the carburetor at lower speeds. It's impossible to test though without driving the nozzle out and getting it on the bench. Someone here had a similar problem a few years back and it turned out to be that nozzle.

[fossil]

Ed,

Take the carb off the 923 and put it on the 925 and see if that fixes the issue. That way you can either eliminate the carb as an issue or you will know it's the carb.

As a caution, if you do drive that check valve out, MAKE SURE you remove the high side mix needle first.

[edju1958]

Changing the carb out from the 923 won't do much good,the 923 carb won't draw fuel.I was going to take it out yesterday to cut,but it wouldn't start.Come to find out it'll only run on a prime.I had that saw running like a Swiss watch last yr.I've got a brand new carb still in the box for a 902,would that work?It's an HS73A.

[fossil]

Mar 15, 2020 13:45:24 GMT -5 edju1958 said:

Changing the carb out from the 923 won't do much good,the 923 carb won't draw fuel.I was going to take it out yesterday to cut,but it wouldn't start.Come to find out it'll only run on a prime.I had that saw running like a Swiss watch last yr.I've got a brand new carb still in the box for a 902,would that work?It's an HS73A.

It should bolt right up. Not sure about the choke linkage. If I recall correctly, some of the older ones had a wire on the end instead of a fat piece of plastic.

If that's the case just prime it until it pulls fuel.

If the throttle wire doesn't match, set the idle speed high and work the throttle crank on the carb by hand.

I see you have the 923 carb going well. That carb should switch over with no issues.

[edju1958]

Thanks Tim! Yeah,I got the 923 going today,so I can put the 28 in.bar on from the 925,or the 30 in.bar from the 450,they all have the same bar mount pattern (D096).The 923 is 82cc,so should have no problem pulling the 28 in.I'll see about swapping that new carb onto the 925 over the next couple of days.I ran the 925 earlier & it seemed to run better after the Seafoam got into the system,but I let it set while I worked on the 923 & when I went back to it it wouldn't even start.

[edju1958]

I went to put the HS73A on the 925 this moprning,but I noticed that the choke butterfly was missing.I guess I got screwed on that carb.I then located an HS26A that I found was used on the XL-901's.Believe it or not that carb was on an old blue & white SXL.I swapped over the kit from the HS151A to the HS26A & put it on the saw.The saw will only run on a prime,but it sounded much better than when the HS151A carb was on it.I'll pull the carb again tomorrow & go through it again & give it an ultrasonic bath.It's probably been sitting for the last 25-30 yrs.or more.Hopefully the ultrasonic cleaner can dislodge what's causing the problem.I think the HS151A is toast.

[edju1958]

I pulled the HS26A off yesterday & was going to dismantle it & put it in the ultrasonic cleaner,but I found the new metering lever to be set way too low & it was preventing the needle from unseating to let fuel in.I took that lever out & put the old lever back in with some minor adjustments.I just finished putting the HS26A carb back in the 925 & after a few pulls it fired right up.I had to make some minor adjustments to the carb,but I don't think the 925 has ever run better since I've had it.It revs up nicely & idles perfectly.It's a runner!