It's a 2 cycle - don't know if it's one they put in a saw..

[boltonranger]

I've only made a couple posts here; but I've learned alot from you all.
I have a Kioritz engine in a mantis tiller. I've run it before but this year I didn;t drain it and it wouldn't start. So I took the zama carb out, which has fully adjustable jets; and cleaned all the passages. Put her back, and started it up.
The problem was that although I got a good idle; full throttle would bog..rev...bog..rev... with the throttle squeezed the whole time. So after much back and forth adjustment, I decided to use some AS ideas. I pulled the plug, not fouled but not shiny either. Wire brushed it shiny again. Then I decided to check the screen in the muffler. Not clogged, nice and open. While I was there I pulled the muffler and check the piston. Very minor scratch; looked alright. So buttoned it up and tried again. Same weird surging at full throttle.
Hmmm.. Remembered when I was a kid, Pop used to have a bogging problem with his chainsaw; intermittent, frustrating, he adjusted the carb ad nauseum and even replaced it the carb (5 year old saw) Eventually it wouldn't run and he took it to a retired saw tech who fixed it. - - the problem was... the ignition module (031AV, electronic ignition) Saw was cured. So - that's about all I can think of; any of you fellows have thoughts on this behavior at speed?
This is a kioritz echo engine I hope it's alright to put the post here, being a 2 stroke - thanks guys,
-br

 

[pioneerguy600]

I've only made a couple posts here; but I've learned alot from you all.
I have a Kioritz engine in a mantis tiller. I've run it before but this year I didn;t drain it and it wouldn't start. So I took the zama carb out, which has fully adjustable jets; and cleaned all the passages. Put her back, and started it up.
The problem was that although I got a good idle; full throttle would bog..rev...bog..rev... with the throttle squeezed the whole time. So after much back and forth adjustment, I decided to use some AS ideas. I pulled the plug, not fouled but not shiny either. Wire brushed it shiny again. Then I decided to check the screen in the muffler. Not clogged, nice and open. While I was there I pulled the muffler and check the piston. Very minor scratch; looked alright. So buttoned it up and tried again. Same weird surging at full throttle.
Hmmm.. Remembered when I was a kid, Pop used to have a bogging problem with his chainsaw; intermittent, frustrating, he adjusted the carb ad nauseum and even replaced it the carb (5 year old saw) Eventually it wouldn't run and he took it to a retired saw tech who fixed it. - - the problem was... the ignition module (031AV, electronic ignition) Saw was cured. So - that's about all I can think of; any of you fellows have thoughts on this behavior at speed?
This is a kioritz echo engine I hope it's alright to put the post here, being a 2 stroke - thanks guys,
-br

Most Zama carbs I have worked on have a brass power valve in them and if it gets sticky it will cause the symtoms you describe. Sometimes you can clean the valve up with carb cleaner but if not it can be replaced and the engine needs it to reach full power. Pioneerguy600

 

[boltonranger]

Well that helps.

Thanks very much Jerry; I was beginning to think I made a real sin putting this here in the chainsaw forum. It was just that the engine reminded me of my fathers saw the way it acted 30 years ago. I took off the upper and lower "plates" or covers on the carb. I blew out all the holes with cleaner - I saw there is a needle of sorts that pivots and a small screw held it in place inside the carb. this was once I removed the upper and lower parts of the carb case. Is that what you're talking about? I can post a pic if it'll help. Any how thanks for not shunning my clumsy post.
-br

 

[boltonranger]

Should've known.

Went back through the engine. The real culprit was a semi-clogged fuel pickup.
Should've known. Thanks for the help. Runs real sweet now. Wife will be glad to plant grass now.-br