028Super, kind of an odd running symptom.

RED-85-Z51

RED-85-Z51

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Let me first cover what ive done....

1.Piston visually inspected good
2.150psi compression
3. Crankcase held vac and pressure fine.
4. Carb inspected and a new diaphragm installed, Carb pop tested good.
5. New fuel filter, oem line is a bit soft but held pressure.
6. Idle will hold as low as 1660rpms and do it as long as you like.

Now, what it is going. Fires up in 2 or 3 pulls from cold, idles strong. You rev it up and initially it feels fat, but if you hold it, it leans out and goes, in my opinion, too lean. My tach freaks out when I hook it up to this saw so i have little tach info. But the plug reads lighter than id like, if I go richer on the H needle, the initial bog feels fatter but the actual top speed seems unaffected. Eventually it gets to the point where it will no longer clean up..too rich, so I hold it wide open...and give the H needle a slight twist in and it takes off to that Lean high rev condition.

To be clear though, it doesn't run away...it feels like its hitting 13,500...its not wound up like an ms260 but its going above the 12,500 max speed.

Ive got a complete carb kit coming for it...and a new fuel line, but short of those im drawing a blank.

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JonCraig

JonCraig

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Which carb is installed? If I recall (and my memory is foggy) the WT1 (or WAT 1 or whatever... it has a single digit number if I recall) is the better carb. Sounds like an air/fuel problem to me. What about the intake boot and/or impulse? I had one that acted really funny until I found a tiny slit in the rubber intake boot that was opening up at higher RPM.
 
RED-85-Z51

RED-85-Z51

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Which carb is installed? If I recall (and my memory is foggy) the WT1 (or WAT 1 or whatever... it has a single digit number if I recall) is the better carb. Sounds like an air/fuel problem to me. What about the intake boot and/or impulse? I had one that acted really funny until I found a tiny slit in the rubber intake boot that was opening up at higher RPM.
WT-16B as I recall.

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RED-85-Z51

RED-85-Z51

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Rebuilt with another kit, no change, put on a chinese carb, immediately had results. Im going to replace the boot as a preventative thing, its hard.

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