No compression solved! TaoTao 110
 

Here's a new one on me & a warning for all.
First let me say users of this forum are very fortunate to have people like Lynn Edwards to help troubleshoot & provide manuals. Thanks again, Lynn!
With spark & fuel, finding low compression was quickly found- almost no blow out the spark plug hole. We removed the valve covers & at TDC, the intake rocker was very loose. Blowing air into spark plug hole, blew air out the intake port (carb pulled off). Looked into the intake with light & mirror-saw a small nut lodged under valve. It was wedged tight but with 2 people, one tugging on nut with a seal pick & the other depressing valve with a screwdriver, we were able to fish it out- compression restored, engine started right up after reassembly.
Where did the nut come from? A vent hose is attached to the back of the air filter with a jam nut on the inside of the filter, a perfect path to destruction. I think we may have lucked out because this one jammed the valve while at idle.
Lesson learned: Some dealers of these Chinese units clearly don't check or tighten anything. My son bought this for grandson so I didn't see it until it was broken, but found almost everything installed to be loose or improperly installed, including the rear wheels. If you cannot but a non-Chinese ATV, at least have a qualified mechanic (likely not the seller) go over the whole thing if you are not mech inclined- remove or tighten & seal this nut on the filter.

Thanks for the complement. I'm have to admit I'm not the best when it comes to mechanical experience. I'm somewhat mechanically inclined, but I just don't have much actual quad experience. If my quad hasn't broke that way - then I really don't know... This is where MWQ and others surpass me by far and provide valuable support. I'm think I'm pretty good at electronics, but sometimes I'm also wrong, and am amazed at what I can learn from others. It's a community thing.

And also, thanks for the report. One of the nice things about this forum is how the info here always seems to come up at the top of search engine results. This post is sure to help many others down the road :).

Welcome to the forum Covey534! :)

Was this a brand new quad? if so how much run time before this happened? what size nut?

Tao Tao 110 compression
 

Brand new Tao Tao. Failed on first day of use, fortunately at idle. Nut was typical 10 mm (wrench fit).

Aint that something? If there are no bolts in the air filter assembly.. Id say it fell in at the factory.. maybe the engine factory, but more likely when it was assembled..

no compression Tao Tao 110
 

A threaded fitting (on this model) attached to an overboard vent line slides through a hole in the back of the filter. Only the nut is on the inside, to lock the fitting in place. On any engine, there should never be a removeable nut, screw or fitting between the filter & the carb that has the potential to be sucked through the carburator.

Thats real nice.. I think others will have the same problem.

I do wonder if the nut did any damage to either the valve or the seat.. but if it runs I wouldnt sweat it..

Chinese Tao tao 125 D no compression bent exhaust valve
 

Child riding/driving ATV - dies won't start
Feels like the starter is spinning free willy - take apart starter fine - motor turning with spark
Then I read and viewed some smart guy said poor oil down spark plug if compression does not improve ( I think utube) then it's rings or valve
Or even both sometimes -- it was beginning of the 2nd season and the airfilter was well lubricated so I doubted it was rings.
Took the head off this 4 stroke and discovered it was the exhaust valve bent bad

2nd slightly used cylinder head exhaust valve bent as well
 

I would have liked to have posted pics but i do not think my status allows such.
PS Sorry it's "Pour" Oil
Pretty scary - I purchased a 2nd slightly used head from the person i
purchased this Atv new as he was honouring a warranty i think and he said the motor from which it came was running but when i got home genius here only then took a closer look the and realeazed there was tiny bit of light appearing or shining through when i looked down the exhaust port. -- So genius here took it apart thought he would have to seat and grind valvle by hand with valve grinding paste or perhaps try some grease mixed with scouring powder like old dutch or comet or vim to seat it lucky i did as this "new" cylinder head also had a slighly bent exhaust valve and would have lost so much time and effort trying to adjust valve clearance at 2 thousands of mm on the intake valve and 4 thousands of mm on the "problem" exhaust side - - over and over again and never thinking the same problem twice.
PS maybe we should be adjusting valves clearance more often or bad valve housing or weal valve metal ?????

Tao Tao 125 4 stroke forward and reverse
 

Update:
I just purchased and exhaust valve for $6.00
Will keep you posted as whether or not i get this running again without having to purchase complete cylinder head