[update aug 2022] this is kolpin brand atvs as sold by gander mountain, 90cc.
owners manual attached lower down in thread.

hi all - new to this world. I bought my 7 year old used quad with no papers and i can't find the VIN.
was running great and will run great again i'm sure if i put back on the stock air box.
I ordered some cheapy stubby filter and now it dies in regards to power after the first jab of throttle. i'm guessing i need bigger jets to offset increase in airflow.
is it worth doing that?
to get the atv to run better, i had to tape up almost the entire air filter. not perfect but much better than no tape.
i see what looks like replacement filters on amazon but again i don't even know the type of quad this is so help would be appreciated

 

"was running great and will run great again i'm sure if i put back on the stock air box"

So why not do just that and put the old one back? If you must persist with the non standard filter, you probably will need bigger jets, though the first thing to do is give the ones you have a good clean, in case the fault just happened to coincide with the filter change, and it has partly blocked jets. Apache and Polaris used the 90cc version of that engine. Apaches have a racing following and, though now they sell a water cooled version for racing, those who race Apaches are the best people to ask about jetting.

 

u sure that's a 2 stroke? Don't see to many kids machines that are 2 stroke

 

hi - definitely a 2 stroke.
i had to add the "oil injection" oil to a separate reservoir.
smokes like a 2 stroke

so still wanting to know what type this is.
full automatic transmission; sounds like a CVT.

 

Can't enlarge it enough to read the numbers, but looks like something stamped on the frame here.

 

"u sure that's a 2 stroke? Don't see to many kids machines that are 2 stroke"

Apache 100
Polaris 90
Eton 50
Eton 90
CPI 50/90/100
plus a host of others, all used that two stroke "Minarelli" clone engine and, of course, the big seller kids quads were LT50 and LT80 Suzukis, both 2 strokes. Since about 2005 the Honda cub clone engines have become dominant and fewer Minarelli clones are made, probably due to pollution regulations regarding the scooters that engine is made for.

 

dude - you rock! holyl good eye site!!! really still hard to make it out but i got the VIN as RGEDN09C45A000528
and the vin decoder sites say invalid. 10th digit is a "5" so its a 2005.
"RG" is taiwan so that gave me a lead to search and i found what i think is Manufacturer Name: Amstrong Industry Corporation
and then googled found me this:
"Taiwan-made by Armstrong Industry Corporation, the Kolpin brand ATVs are sold at Gander Mountain stores across the country"
So googled Kolpin and found they sell a 50cc and 90cc in 2005.
I am just guessing its a 90CC because it really rips with me on it 170 lbs.

 

Do you still have your Kolpin 90cc?

 

yes i still have this. running good

 

i just emailed them... customer service... long shot but why not. i asked about where to get parts:

https://www.kolpin.com/en-us/