We are new to the 4-wheeler thing and are already having a problem with our son's new Yamoto/Patriot 90cc. When you first start it and take off, you are o.k. After running it for a while and try to idle it, it shuts off. If you can get it started again and try to hit the throttle, it cuts off. If you let it sit and cool off, it will usually start back up and take off again. We bought it a couple of months ago and stored it in a closed garage until Christmas starting it and letting it run at least once a week with no problems. It also smokes really bad, which I am thinking maybe is because of it being a 2 cycle mix. Also, has anyone even ever heard of a 90cc Yamoto/Patriot??? We bought it locally from a guy who puts them together and sells them from home, but there seems to be NO information about this atv on the net. 70's and 110's are the closest I can find. Thanks for all your help in advance. Christmas hasn't been fully exciting with this problem, but hopefully we can fix it!!!

 

I will try to help
1. Are you sure it's a 2-stroke? Some are 4 and some are 2. Verify first!
2. Depending on your elevation, the idle is out of adjustment.
3. Check the air-cleaner. Is it in good condition? Some come from China in bad condition or installed wrong.
4. You will probably have to adjust the needle in the carb, not enough fuel at idle. This is very common with "imports". 9 out of 10 have to have the needle adjusted.
The problem is this, they put those K&N clone air filters on and it sucks a lot of air, but not enough fuel to get a good mixture. Thus the reason it bogs down and dies when you give it gas. During warm up you probably have the choke on closing the carbs air flow, then you remove choke and all the air flows in and not enough fuel to mix. Understand?
4. Maybe your mix is to high on the oil? Check for correct mixture

In the end, #1 thing that goes bad is the carb. Not after owning it, but initially. You might have to take it back or get another. Keep us posted.

 

We will check all of the above listed things. We thought we were getting an atv that was in perfect running condition. The guy we bought it from had put it together and taken it on an 8 mile test run with his daughter driving it. We tested it out at his house and sat with it idling for probably a good 1/2 hour. But of course the night before we are to give it to our son for Christmas, it started its problems. We must be having a string of bad luck because NOW after our boys had a chance to half enjoy theirs (the little one has a new Kazuma 50) my husband pulled his brand new Falcon 250 out of the building and it won't start at all. Guess I will be making another post about that. Guess we will all be riding the Kazuma, LOL Thanks for your suggestions!!

 

Not that this has anything to do with your problem but please never let an air-cooled atv engine sit for half an hour at idle.....2 or 4 stroke. These engines depend on air moving across the cylinder fins to keep them at a safe temp level so you don't overheat the engine.
I hope you get the problems worked out. Nothing more fustrating than getting something for the kids as a gift and it give problems or worse yet....not work. I'm a father so I know all about that.
Someone on here will give you good advice on the problem....just like in the first post.

 

Yes Yamoto is very popular in the Chinese atv scene. On the otherhand I have never seen a Yamoto 90cc 2 stroke. I dont think it exists. They only make 4 strokes. So if indeed you have a 4 stroke atv you should not run a mix. Once these are running they actually run very well. I have had 2 and still have 1. They all have run flawless for about 1 year now. The biggest thing you MUST do is change the oil once you get it. They do come with oil but you cant run them with this oil in it. They come with a shipping oil. If you run it with the shipping oil it will overheat and cause damage. So what you need to do if it is a 4 stroke is drain the gas, replace the plug, change the oil and go from there. And for what ddrumman2004 said is wrong. You can control temperature with the jetting. The richer it is the cooler it runs, the leaner the hotter. One of the best ways to check jetting on a 2 stroke is with an EGT (Exhaust Gas Temp Gauge) to see what the temperature of the exhaust is at. If it is too hot then you jet it richer... So if your jetting is right you will have a more consistant temperature without overheating. In this case you have to let it run at idle for a bit once first started because there is a gelpac in the carb floatbowl that must dissolve before you ride or you will clog the jets.

 

A lot of these type of engines have electric fans to avoid such a thing =) Not sure about their's, but our's do.

 

Thanks for everyones suggestions. If anyone else has any ideas, please feel free to post them.
The atv we have says it is a Patriot and has a sticker reading 90cc, it is an automatic. As far as the oil goes, it has a tank for the oil and a tank for the gas and it mixes itself, the guy told us to put 2-stroke oil in it (which he did already when we bought it) Our Kazuma's (Meerkat 50 and a Falcon 250) we bought from a dealer which is what we should have done with the Patriot I guess. The guy we bought it from has been helpful in giving his suggestions but nothing has solved the problems as of yet. He just purchases them and puts them together then sells them, doesn't have a shop or anything to work on them. It sounds to me like it should be something cut and dry. It starts the first time we go to ride and does o.k. if you idle for less than 30 seconds. After you ride it for a while and try to idle, it winds down and cuts off. Then when we try to start it either by kick starting or electronically it is really hard to get going again, and once you do it cuts off as soon as you hit the throttle. If you let it sit for a bit and try it, it usually will go without a problem. Guess I am off to post a message about my husbands now, we have tried all day to get it started with no luck. Where is Santa's magic when I need it? Thanks for taking the time to answer!!!

 

Desertbum, We tried charging the battery and we did get it to start about 3 times today for about a second each time, the other times it just whines but won't start. We checked simple things like making sure the gas switch was on, gas was in the tank, the kill switch was in off position, all the simple things that we could think of but these are our first atv's and don't know what else it could be. Thank you for answering!!

 

On your 250cc do you need to use the foot brake to start it? If so, try using the hand brake. If it starts and runs, I will walk you through how2 fix the foot brake then (the rear brake switch is bad or needs to be re-aligned). Post back on how this works.

Ps. Did you charge it until it showed "full charge"? If the starter spins some (the sound you hear) but no start, my experience says that battery is low or bad. You may need a 12 hr charge. Walmart sells the batteries for $19.95

 

When this happens you may want to adjust the air/fuel mixture screw or change the needle jet position.