does anyone know where i can get a service manual for a maxam 70cc atv. there is a hose coming off of the top of the engine towards the front of the engine and i beleive i am getting low compression because it is not hooked up anywhere but you can see it was connected to something at one time, cant figure out where it goes?

my son a I are now at about 6 weeks and still cant get it going

c.b. rookie

 

i don't know where to get a manual for your quad. but i'm beginning to think that the hose you're talking about is the "vent" for your cylinder allowing blowby. i'm a little unsure though, if this were to spit out oil, then we'd know that your rings are probably bad. that's what i'm thinking about the hose. i could be wrong. let me see if i can dig anything up on this matter. i'll hurry as best as i can to help you out on your quad.

 

thanks jaster but dont rush we are leaving for a few days of camping and family time will be back on atv duty next week . I beleive it is a vent for the valves that was my thought also. I found the engine ratio for compression on line it is 8:8 / 1 which i convert to about 130psi this seems high to me for a 70cc? going to go and purchase a proper tester also in your search if you find out what kind of engine it is please let me know if the valves or rings are gone it might just be cheaper and quicker to purchase a new engine.(just a thought) I found the engine number stamped but when I plug in the # it just comes back as not found. Yes I replaced the coil and put in a brand new carb.

 

I'm not an expert on engine compression measurements, but I'm curious how you came up with the 130 PSI number...

I see that 130 PSI divided by 14.7 PSI (atmospheric pressure) equals 8.8 (roughly), but I'm pretty sure it is much more complicated than that. For example the air heats up on compression which will raise the compression reading, and the intake valve closes quite a ways after bottom dead center so your not getting a full stroke on compression.

If there is anyone that knows they can chime in, because I don't know the answer....