Husqvarna cement saw trouble at high RPM.

[albert611]

Little help with Husqvarna cement saw k970 96647-3900095 sn 2011-3900095 with walbro Rwj5-1 carburetor. Saw idles ok when you start to cut wants to boug down at high rpms new carburetor thought this was problem, just acts like it's starving for fuel, checked exhaust. Thanks for any help out there.

[KE4AVB]

Looked at an image of the carburetor. I couldn't tell if it is adjustable or not. If it is adjustable then try returning the H mixture.

[albert611]

Thanks, tried that brand new carb, turned jets in and set to standard no good tried different adjustments no good. will not hit high rpm without load yet alone cut. guess i can do i leak down unless someone can spot smothing i am overlooking.

[KE4AVB]

Do you have a spare ignition coil on hand? It could be a failing trigger circuit in the coil. I had a Homelite a couple years that would idle all day but would not accelerate pass mid throttle with an occasional backfire.

[Arkie]

Be sure that the H jet is not out too far. try turning in the H jet about 1/2turn CW from where it sounds good or where it is now.

If a fuel line is sucking air the saw will sometimes still idle but not go at High.
Also some saws have a screen or filter in the CARB and they will idle ok but not accelerate.

If a crank seal is leaking the saw will usually have a erratic idle, but not always. Do a vac/pressure test eventually.
Make sure it has the correct spark plug and it's tight.
Had saw awhile back that had those issues and it was the filter in the carb clogged. Had another that the fuel line from tank to carb had a small crack. (both saws would idle good but not carry a load in the cut)
A over rich H jet (to far CCW out) will sometimes also do the same on some of the big saws.

[KE4AVB]

A lean H jet (to far CCW out) will sometimes also do the same on some of the big saws.

If I not mistaken these mixture screws should be RH threaded and would enrich and not lean it by turning CCW. Personally I haven't seen left handed versions yet but knows they might be out there.

[Arkie]

A over rich H jet (to far CCW out) will sometimes also do the same on some of the big saws.

If I not mistaken these mixture screws should be RH threaded and would enrich and not lean it by turning CCW. Personally I haven't seen left handed versions yet but knows they might be out there.

You are correct: (thanks)
I edited for a correction.

Main thing is try carefully adjusting the High jet by 1/2 turn increments and test under load, (sometimes just a 1/2 turn of the H jet will make a big difference when under load) but do not leave the jets set overlean (too for in) on finals. (usually mentioned in final adjustment manufacturer procedures to not leave the jets adjusted too lean can result in a scored piston due to lack of lubrication and or too high rpm's)

[Fulltilt]

Little help with Husqvarna cement saw k970 96647-3900095 sn 2011-3900095 with walbro Rwj5-1 carburetor. Saw idles ok when you start to cut wants to boug down at high rpms new carburetor thought this was problem, just acts like it's starving for fuel, checked exhaust. Thanks for any help out there.

Did you actually pull the muffler and check the exh. port in the cyl. , or just check the screen?
It could be the coil, as was mentioned.

[albert611]

Thanks, all great ideas, might take a while to track down a coil I can do all the other things I have a leak down tester, will let you know.