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Discussion Starter #1
Having a problem with an Echo GT1100 trimmer.
Engine is 21cc
This has a single ring piston.
Light scratches no deep scores in cylinder.
The cylinder has it's cross-hatching still.
I rebuilt the carb & replaced the crank seals.
Compression is 125 psi.
I read elsewhere that these trimmers typically have 120-130 psi.
I did replace the ring but compression did not seem to improve.
The new ring only got to 100 psi. The old was 125.
This may have been the seal on my compression tester - I could not tell.
My tester screws in too far before seating so I used some teflon tape on the threads and didn't screw in too far to avoid hitting the piston.
Difference between old and new ring is negligible thickness-wise.
Old ring has chamfering on upper and lower edges
Put old ring back in when new ring did not improve compression.

Set coil to .012" air gap. (Would larger gap (.014-.016) change anything?)

Here's the trouble:

Got it running; idles well.
Will accelerate and hit wot (8k-10k wherever I set it)
but has about a one second bog on the way up.
If I squeeze the trigger slowly it comes up okay but if I goose the throttle it bogs just a little as it takes off. Enriching the hi only works to a point. Never quite enough to make the small bog go away.
I've tried enriching the low jet to the point the idle is poor,
but it does not help.

Does this sound like symptom of the metering rod setting being off a little?
Or something else?
I can use the trimmer; - just real annoying to have the small bog considering the time I spent on it.
-Appreciate your thoughts.
-br
 

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I just cleaned the carb on my srm2100 and runs great now. I had to adjust my low/high needles too. Are you positive you got the carb completely clean? Mine used to have a little bog too, but gone now. My piston/cyliner still looked new. Did you clean the muffler?
MU
 

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Discussion Starter #3
Fairly certain carb is clean.
I spent the time to even replace the welch plug.
Muffler screen is also clean.
Feel like I'm running out of things to check.
-br
 

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Spark plug is a Champion RCJ6Y? or CJ6Y? Gapped aat 0.025"?

Id like to see the compression on that model in the 135 range, but 120+ is good enough to run right.

Turn both needles in all the way to a soft seat, now turn them both out 1/2 turn, and screw your base idle adj. out 1/2 of its travel on the taper.

Crank it up and hold it wide open. Turn the H needle out until it tachs out to 10K. Now return to idle. If it idles at all ,bump it wide open. If it hesitates, screw the H needle out 1/4 turn until it accelrates immediatly off idle. Now retune the H needle to 10K again. If you end up with a low idle, or a high idle, but it accelerates smoothly, turn the base idle needle to where it idles properly. The idea is to have the base idle needle as far closed as possible..

If it still refuses, the only other thing Ive seen cause this on Echos is a worn out clutch. The springs are weak and engage too soon, before the motor gets up into its powerband, and hook up instantly instead of gradually...makes the engine bog until it can get into its powerband.
 

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Discussion Starter #5
Spark plug is a Champion RCJ6Y? or CJ6Y? Gapped aat 0.025"?

Id like to see the compression on that model in the 135 range, but 120+ is good enough to run right.

Turn both needles in all the way to a soft seat, now turn them both out 1/2 turn, and screw your base idle adj. out 1/2 of its travel on the taper.

Crank it up and hold it wide open. Turn the H needle out until it tachs out to 10K. Now return to idle. If it idles at all ,bump it wide open. If it hesitates, screw the H needle out 1/4 turn until it accelrates immediatly off idle. Now retune the H needle to 10K again. If you end up with a low idle, or a high idle, but it accelerates smoothly, turn the base idle needle to where it idles properly. The idea is to have the base idle needle as far closed as possible..

If it still refuses, the only other thing Ive seen cause this on Echos is a worn out clutch. The springs are weak and engage too soon, before the motor gets up into its powerband, and hook up instantly instead of gradually...makes the engine bog until it can get into its powerband.
Well thank you for such a concise answer Red;
I will give it a try.
btw plug is ngk bpm 7y I think.
Yes it is gapped to .026
-br
 

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Echo is famous for blowing the crankcase seals and lower crank seals. Take a look at them.
Ive only seen it twice, and both were on PB-200 blowers, both happened in the shop while being serviced. Runs great, you get a misfire and a pop..motor shuts off and refuses to crank or try to crank after that. It also sounds different while cranking.

Both times the kill switch was dirty and not grounding properly, causing a misfire.
 

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Discussion Starter #8
I think now that the clutch springs are weak.
If I goose the unit while it is spinning above idle (like while it is winding down from full throttle, It takes right off.
If I remove the shaft from the motor it doesn't bog if I rev it from idle.
Thank you all esp. Red.
:trink39:
-br
 
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