Any way to make sure I am not ruining my motor?

[BeefySTi]

Long time lurker, occasional poster. This is an awesome site for info and maybe you guys can help me out.


so, back in the spring i bought a 2001 400ex. got a great deal on it and it needed little to get it going (battery, brake pads, clutch cable, oil change, normal maintenance, yada yada yada).

When i went to check out the quad the owner said it had been bored over and it had a k&n filter and an older style aftermarket exhaust by big gun. It was his son's quad and he was grown and in the military and didnt ride it anymore. it had been ridden about 5-10 hours in the last 5 years. but we got it started pushing it down a hill and dumping the clutch and it ran fine, and sounded good. the issue was, the guy i bought it from did not bore it over, and was not aware of what was done to it. So i have no idea what the displacement it is currently at.

I have ridden it all summer and have had no issues beside a little smoke when I started after it has been sitting for a few weeks. If i ride it regulary (once a week) there is no smoke. it pulls hard, and my buddy has an 04 ex that it keeps up with and will occasionally outrun if i do my job right with shifting and clutch. His quad is not stock (aftermarket cam, full exhaust, filter). I am also about 100 lbs heavier than my buddy. so needless to say the thing starts right up, runs great and has caused me no issues.

my question: is there any way to tell if i am jetted correctly and not doing damage to the motor over time? is there a way to know what displacement i have without cracking the motor (i highly doubt it, but i thought i would ask anyway)?

any help would be greatly appreciated. and please, i understand that it wasnt the smartest decision to buy without all the information on the displacement, but i was admittedly new to atv's and didnt know what i was doing, so keep the flaming to a minimum, haha.

and yes, i know this is a loooong post, but i felt some back story was necessary.

[duneslider]

I wouldn't worry about displacement until rebuild comes.

Pull the plug and see what color it is. You are looking for a tan to brown color to be jetted right. If it is grey to white it is too lean which is not good. There is a really good post or two in the faq about jetting and plug reading.

Smoke could be a lot of things and many aren't a huge concern. Have you adjusted the valves? That would be good to do/check.

[BeefySTi]

I have done a valve check, and they were within specs. there are no ticks or knocks either.

the plug definitely wasnt white/gray when I changed it. if anything, it was brown/black. so i could be running too rich. which from what i understand is not great, but a lot better than running lean. i could just be robbing some power from the motor if i am to rich, right? nothing damaging to the motor about running rich?

and, thanks for your input.

[duneslider]

The biggest issue with being too rich is poor combustion which would cause carbon buildup. I doubt you are that rich because we would be having a different conversation. You could be missing out on a little power though. Might be worth dropping a jet size and checking.