I have a Manco 90cc youth atv, ( I know....Manco--Taiwan junk but I can't complain when I got 2 for $300.00 )
Anyway, One of them runs great for about 5 or 10 minutes then acts like it's out of fuel ( full tank ) and won't start for about 15 minutes, then runs good for another 5 minutes or so then does it again. I have replaced the fuel filter, cdi, coil, and spark plug. No help there, anyone got any more ideas? Also, what can I do to increase power, (mods, etc.) Thanks in advance.

 

The next time it dies, open the gas tank cap and listen for air sucking in. The vent valve in the cap may be bad and the motor may be sucking a vacuum in the gas tank. Even if you don't hear the sucking sound, open the cap all of the way and then reinstall. Then try to restart the quad and see if it will run.

 

Tried starting it with the gas cap off and back on, no help. Ran it in the yard till it stalled again and got it to start right away by covering the air intake with my hand (like a choke) but then it dies again. Thanks for the thought though

 

The next thing I would check would be the valves.

 

How would the valves cause this? IE; What am I looking for?

 

If this is your quad you do not have any valves to adjust. You might try giving your carb a thorough cleaning.

As far as upgrades go it helps if you could post the specs of the quad. (IE. 2 or 4 stroke CVT or other trans and any other info that would be helpful). Members need to know what exactly you have in order to help you out.

If this is a two stroke, it quite possibly could be a distant cousin to the Unison 90 coming out of Taiwan.

However, once you post additional information, I'm sure others who own this quad will probably start posting and letting you know what they have done as far as upgrades and performance boosts.

Anyways, Good Luck,

SB

 

My bad. I assumed that it was a 4-stroke.

 

Thanks Smb05, it is the one that you you asked about. It is a 2-stroke. As far as tranny, i'm not sure, all I know is there are no gears to change. I don't know a lot about them as these are the first I have owned. I do know they have a good bit of power since my sons (which ran and continues to run good after I cleaned the spark arrester screen) will carry me plenty fast for it's size. Thanks also SilveradoSS.

 

Does your quad have a manual choke or an electric choke? If it electric it could be sticking causing your problem. I would start by going through the carb. My artic cat 90 carb was filthy when I bought it. Has run great since.

 

I bought a 90cc manco for $75 off Facebook market and they guy said it needed a new battery and a carb clean so i brought it home jumped the battery it ran for like 15mins and died so I pushed it home and jumped it again it idled fine but once I tried giving it gas it died so I bought a new battery installed it and tried starting it but it had like no power so I gave it a jump using a car battery it started ran for about 20 mins then died so I don’t know what’s wrong but does anyone know what’s wrong with it??