350 mile cyl teardown.....

time to go to treatland for a $23 puch head. just the machine work is worth that!

Hey B,

I guess I got a differing opinion of what I see...
(pretty nice pics...)

IMO

It seems to me this photo-spread is kinda confirmation that just about everything we feel abt chinagirls is correct.

...It would be a great idea for everyone buying a new chinagirl to follow Alf's advisory for new motors...l

Here's my take on why Alf is a wise fellow, in part...

That cylinder head is drilled too close to the combustion chamber to provide suitable sealing surface for marginal parts used in these assemblies... whatever may come down the line, today, or next week... everything is from job shops... and QC is basically non-existent.

The cylinder actually looks poor. The wear pattern is really shabby.
It is spotty, and shows many signs of binding and other seizing and hang-ups,though nothing really serious...

Basically, what I see is a sure sign that these cylinders should be honed out before they are started.

As you said, the flashing inside the port is yer basic hand grenade looking for a time to happen.

Let's talk about the rings and piston.

An awful lot of soot on top the piston crown, the rings seem to be totally gunked and sludged, and there is black sooty sludge beneath the rings and their lands n grooves.

Among other things, I think it might be time to re-visit your break-in procedure, and the oil/mix ratio employed... and the run-in process.

The rings didn't seat properly, soon enough.
They are NOT the best quality rings, but we don't hear of them breaking in actual service very often... I think proper honing might be a good idea...

Everything about the amount of soot, gathered in less than 400 miles says the mix is too fat, and too oily.

Part of the cylinder head did apparently burn itself clean, so it was getting up to operating range in temp. It doesn't seem to show any scorching, nor does the piston skirt...

Perhaps someone wiser than me will come along who can read that piston & cyl head to determine what is really going on...

Also, in my opinion, a two stroke cylinder head is little more than a chunk of aluminum to provide a combustion chamber. if it's got suitable fins, and a hemispherical shape, perhaps with a fancy squish band, they are all pretty much equal.
I don't think a chinagirl warrants expense of a puch head.... that is to say.

If the stud holes were not so large on the factory head, and close to the effective gasket compression zone, it would work dandy. Certainly not as kool looking as a puch head, though.
Boost bottles look kool, too!
And it's even more fun to tell people you are running a boost bottle!

But that's all what I think, from looking at your pics.

I'd get a second opinion!

Good luck
rc

Just don't hone one of these, or you'll have more than a little carbon and soot to worry about.

lol

OK, Joe...

What would you think of at least trying to break the glaze with some wet n' dry, before it is fired off...

it just seems to show odd wear patterns, and the rings obviously didn't seat...

...would you be more critical of my 2cents, above???

Best
rc

rustycase said:

lol

OK, Joe...

What would you think of at least trying to break the glaze with some wet n' dry, before it is fired off...

it just seems to show odd wear patterns, and the rings obviously didn't seat...

...would you be more critical of my 2cents, above???

Best
rc

Click to expand...

I wouldn't discourage it if done very carefully, or even a VERY light hone with a ball type hone, and by an experienced person.
That chrome coating is mighty thin!

Your critique was pretty thorough.

NEVER run at 16:1 fer cryin' out loud...

Here's my break in- never broke one or had a break down.

I use 40:1, (Penzoil) and run moderately hard with lots of throttle and load variations.

Don't run long down hill, throttle off runs, or load the engine at too low of an rpm.

Do get the rpm up a bit and give it WOT to seat the rings.

Higher rpm don't hurt anything, as long as you warm the engine up thoroughly before you run it up.

With two strokes, especially until you get some time on them, it's really important to get some heat in the engine by running easy for a few minutes to avoid 'cold seizure'. (that's where the piston skirt expands faster than the cylinder, and you get cylinder wall/piston skirt scuffing, partial, and possibly full seizure).

borntofli said:

I'm assuming most of my carbon buildup is from the break in ratio...16-20:1 for a couple gallons of gas..Then i'm at 50:1 amsoil.....I probably work it too hard during breakin....I have to pull a trailer for work .....

I'll pull it apart in a couple weeks when I get another 5-600 miles on it and see how it looks....

Click to expand...

You can't really 'work it too hard' as long as it is fully warmed up before you go haullin' ass with the trailer.

Carbon build up, and rings not seating are likely from the 16-20:1 bit.

Yep!

I agree very much with Joe.

And...
If I were to run a fat mix of 16 or 20:1 in a new motor, it would NOT be a synthetic, and it would only be a beer can full, for the very first start and heat up run. I would immediately switch to thirty or forty to one.

In my experience, I've seen a LOT less ash buildup when I ran synthetic, and actually feel more power. Never tried the Opti2 stuff, but I would like to, one day... Now I run any kind of 2 smoke oil I can get my hands on, usually blend em all together, and mix at about 40:1 with a well run in motor.

I would be cautious on any WOT running, and allow the engine to run through cycles of heating up, and cooling down... that is to say, allow it to run free and easy a bit after it has been loaded heavy, with a throttle on situation.

Additionally, I would NOT tear the top end down again, for inspection, as a matter of course... Just run it!
You can inspect a plug to find out most of what's going on, and look in through the exhaust port to inspect cylinder walls and piston skirt condition.

An overall situation we have here, with the chinagirls, is that the metallurgy and basic quality is always suspect... Excess tinkering will wear out the threads machined into the components!
If it's running well, let it be!

Best
rc