Definitely a project

[TexasT]

Unless you are in a big hurry to pull it apart, I would put some acetone/auto trans fluid in the cylinder and let it soak overnight or a week, to possibly loosen those rings up enough to get it fired off. Running it, I would think, would loosen those rings up. But I'm a cheapskate with more time than money. Even a premix two stoke gas down the plug hole and some into the intake to maybe get it to run a bit and give it some lubrication could help. Amazing what some heat does for stuck metal.

[Steve Wood]

Nothing ventured, nothing gained. Won't hurt to try. 👍

[nocooler]

I mixed about half a quart of atf in the first oil change for our kart. It’s got a couple hours of run time and due for a change now, and the detergents are working it’s nasty looking.

[Steve Wood]

I know there are a lot of opinions on oil, but I believe a high quality oil that has zddp in it will make these engines run longer, better, and cleaner.  I see quite a few use synthetics.  Seems like a good idea to me.

[Scoobum]

Jeremy...pour the ATF to it. It's 75 percent detergent. I had a tech teacher in college that ran 50/50...oil and ATF in his mini Cooper. When he pulled it down after a gazillion miles it was crystal clean.

[reality]

Diesel works good too.

[Steve Wood]

Damn, Ron!  You must be old!  I have not used diesel in oil since I sold my '53 Ford convertible.  I used to mix it up and put it in that flat head about once a year and let it run a bit.  Damn sure kept the sludge out.  I never put toilet paper in the filter tho LOL

[reality]

I'm not the oldest guy here but close.

Back when toilet paper was paper you could get away with using it as a filter, the new stuff not so much. The tolerances were looser then also and a little soft debris would just pass through. LOL

Don't they sell something similar now?

But yea soak the cylinders in diesel for a day or 2.

[Steve Wood]

Age is the race I would prefer not to be in...but being 80, I guess I am a definite contender

Well, set the valve lash and still had 60 psi of compression.  Did a leak down test and had 80% leak down. 

Slight leak out the intake side and did not hear anything out the muffler. Did not hear any air when I pulled the deep stick out.  But air was coming out of the top of the head area like crazy.  Head is open to the crankcase around the timing chain.

I guess there is nothing to do but pull the head and cylinder to see if it is stuck rings, cracked something, or whatever.  Definitely ain't gonna run that way.  I did not plan on becoming at Chinese clone mechanic at my age.

[nocooler]

Sounds like time for some upgrades!

[Steve Wood]

haven't been able to get the pin out of the piston yet..one circlip out but the pin does not want to push out.  need to get better light on it and see what is holding it...don't see the other clip...old eyes and poor lighting at the moment.  Part of the top edge of the piston is melted off so I guess it was run hard and too lean too long.

Rings look pretty well messed up.  Looks like i need piston, rings, and cylinder at a minimum.  Piston is pretty badly galled in one spot at least.

I am not really clear as to what big bore kits are available.  They are not mentioned too much for the karts.  Usually, you can go from 150 to 170 cc just swapping parts but for some reason, I don't see much about it with regard to this kart.

[nocooler]

I'm seeing quite a few options available on amazon, reasonably priced too.

[Steve Wood]

Prices are reasonable but the reviews make it look like it's a crap shoot.  You get a lot of stuff for the money which makes it likely that they are not always the best made products.  There are some really good stuff out there for the scooters but I notice it is not guaranteed to fit the Chinese built go karts.

I still have not managed to get the pin out of the old piston.  I pulled the circlip out of one side and the pin comes up to the edge but then won't slide out.  I don't see a clip on the other side so I must have broke it when I hit on that side without thinking about it sticking down.  Looks like the piston crown might be knocked down over the pin hole a bit but it does not seem to be stopping the pin.  Looks like I am going to have to dremel it some

[nocooler]

I agree it's a gamble, but it's all chinese shit anyways not like it was high quality from the factory.

[Steve Wood]

There is some really nice Taiwanese stuff out there but it is not a guaranteed fit altho it should fit.

I think the boost was too high and it detonated.