Motor gets weak when hot...

[Bent Spoke]

You've blown your chance to break in your engine by babying the motor.

Re-ring the engine, and rehone the cylinder lightly or get a new cylinder.

Use 32:1 mixture and run her by varying engine load and rpm. Rings seat with combusion pressure and light loads won't push the rings firmly enough against the cylinder to break in. Full throttle is fine but do it going up hills and on flats (varies load and rpm).

X2

20:1 is an insane mixture

I broke mine in a 32:1 and hammered on it to break it in. babying a new motor does more harm than good.

if this works on a $1200 chainsaw running at 14,000+ RPMs, then it's good enough for a cheapo HT motor.

 

[AussieSteve]

20:1 is an insane mixture

Why do you say that?
16:1 is the recommended ratio for run-in, then 20:1.
Surely the designers/manufacturers must have had a reason for that ratio. They were smart enough to design the engine. I'd assume they were also smart enough to know what fuel/oil ratio to recommend.
I'm running mine at 16:1 during run-in - no plug fouling, no smoke trail, plenty of compression, (115psi w/ stock head).

... Steve

 

[Bent Spoke]

Cause they listed that ratio to be used with 30w oil, in fact with too much oil it will prevent proper break in resulting in excessive blowby.

There are hours of reading when in comes to oil:gas ratios and it seems everyone has their own opinion on it, so I say go with what works for you.

As for compression ratios, I'll post up what I have, using 40:1 WoodlandPro 2-stroke mix, (my chainsaw/weedwacker premix) just for comparison sake.

 

[AussieSteve]

it seems everyone has their own opinion on it, so I say go with what works for you.

Yep, we all do that in the end anyway.
I understand your point about weedeaters, but they aren't (usually) loaded as heavily as these little HT motors.
Also, it wouldn't shock me too much if the weedeater is better engineered.
With 2-strokes in general, keeping the mix a little oil-rich is important for compression. More so with these engines, due to bad engineering. (Good design, poor engineering/manufacturing)
The more oil, within reason, that you can put in and get them to run cleanly, the better. More often than not, an oily/fouled plug is due to a rich fuel/air mix or too cold a plug heat range rather than excessive oil.
As I mentioned, mine runs very cleanly on 16:1. (When I pulled it down, though, there was a little bit of blow-by evident, so I am looking forward to dropping to 20:1.)

I personally wouldn't run less than about 25:1 or thereabouts.
Too much oil is infinitely preferable to not enough.

... Steve