Hey guys looks like no one posts in the atv section but ill give it a try.

I have a kids 125cc coolster quad. It was brand new. But i think we didn't break in the engine right. Because we made the mistake of gunning the engine full throttle for long periods of time. Now The engine is smoking a little bit, And there's a bad rattle noise coming from somewhere i cant really tell from where. But i thought it might of been the valves, checked them and they are good. Also when i took the valve covers off i didn't get any oil dripping. Which you usually do, So i thought that was odd.

So i went ahead and started the engine with the valve covers off and I did not get any oil squirting out of the valve holes, So im thinking has the oil pump gone bad? Which isn't letting oil come in to the front were the head is? Also forgot to mention after a while of riding it the engine over heats and you have to wait like 5 minutes to ride it again and it lasts another 10 minutes until you have to wait for it to cool off. I checked the oil level and its right were its suppose to be. thanks

First let me say that if your motor is over heating, you should not let it cool then run it again. You need to address the problem. Thats a good way to kill a head or motor for that matter.

Second, some guys break in motor how they run them while others take it easy. On the stock cars we ran them hard for short periods then eased of to let motor cool. On the buggy I run it with non detergant oil, and never take the throtle over 3/4 but riding about the same other wise.

Now maybe your rings did'nt seat so its smoking I dont know. You need a comp test and check your valve lash. Make sure their seating and replace the oil pump which is bad. It should be shooting oil in the head and runs off a chain.

I didn't think these small engines used an oil pump. Aren't they a sling and splash system? I thought that is why there is a question about the usefullness of a filter on a gy-6 150 motor. Some oil should be getting carried up to the cam by the timing chain. I had a valve stem seal that failed on a gy-6 after about 20 hrs. It didn't smoke a little, it smoked a lot. I could put a mosquito truck to shame. You mentioned overheating. Are you sure your not running lean? What did the plug look like?

alright so i took the engine apart, And theres evidence that not enough oil was coming to the front. The valves were a bluish color. And the piston and the back of the head were a yellowish/brown color with bluish mixed in there. The piston was like dry of oil, So im pretty sure i ruined the piston and rings because no oil was getting to them. Now how can i tell if the oil pump is bad? Ill get to that tommorrow if i can find my clutch tool so i can move whats in the way. thanks

Hey rock these little things got pumps. Tom at syc powersports checked mine when building the motor to make sure thats not the reason for failer. They run of a small chain in side the case.

I can take the valve cover off and just touch the key to see the pump work. It pumps of the crank so if the oils not pumping when the motor turns either the chain is off or broke or the pump is bad.

while you have that engine apart put a new oil pump in along with piston and rings. also check the head to make sure the valves are seating and use a stright edge to check the mating surface.

what brand atv is it?

whats up big e...

This is the atv http://www.nationalonlinescooters.com/i ... ProdID=775 i think the oil pump was a dud from the beginning since it did that the first time we rode it, When i bought it we didn't use it for more than 5 min until 2 months after i bought it. And the place i bought it from was having a going out of business sale so i only got it for 300.

I don't mind though since parts are available cheap here. A new piston with rings is 30 bucks. The oil pump im just gonna take out of a 70cc parts motor i have laying around, should be the same.btw what do you mean by checking the seating and mating surface? I don't think the head is ruined since it started right up and everything. thanks for the help.

use a straight edge and lay across the head to make sure its flat. with the head off pour some mineral sprits in the intake and exhaust ports, watch and see if there is a wet spot around the valves. if so then the valves are not seating

Alright the head seems fine. The oil pump was definitely bad, Was stuck and couldn't be spun freely with out it getting stuck a few times. Also the rod that goes to the timing chain with the rubber wheel was broken too. So i am almost done but just need to find a fly wheel puller locally because that sucker is on there tight!

If you cannot find a puller I know at least two dealers on the trusted list that can send one... McDonough and Buggy Depot.