Again, hopefully with brevity I discussed the fuel to air mixture. And I can promise you that more fuel will produce a hot and focused combustion than more oil. I am not discussing the effects of a longer (lower heat/slower/sloppy) burn that the oil properties provide. True, oil will spread and cause a longer burn but not a more violent focused combustion. Plus it take more ignition to completely burn oil vs fuel.

I am disussing the more atomization of fuel vs. air in a 2 cycle will produce a more violent explosion. A very hot explosion cause from a lean fuel to air ratio is like a light focused thru a magnifying glass. A hole will burn into the piston. The discussion of a combustion created with oily fuel and their attributes will not fit into "burned holes in the piston" issue this original thread started from.

There is only so much fuel and oil that the carb will meter, assuming we are using pre-mix fuel. If too much oil is mixed, then less fuel is allowed because only so much fluid (oil and gas combined) can go thru the jets. Less fuel and the same amount of air and we have a lean burn.


In some ways we are saying the same thing, but coming at it from different aspects. Kinda like the horse before the cart syndrome. Both are needed in proper ratios and attributes. But the cause and efect issues are what is differing between us for a "burned hole in a piston" issue. That was the issue I was addressing in respect to leaness.



Thanks for the responses.

Chunky

 

My dealer said that if you run it with too much oil it will burn it up because the oil gets it hotter? I guess there is a tolerance at both extremes. I'm totally confused now. Anyone want to make it simple?
Any info is great!

Thanks,

Paul

 

Pualc,If I had a hand in confusing you then I'm sorry,I kind of left the subject and wondered into a new one. Just ignore my post because Chunky posted the things to get you going. By the way what kind of plug reading are you getting? I know this is a long shot,but have you checked your ignition timimg?

 

Dudes,
Thanks for the info. I would have to ask the mechanic about the plug. Im just an arm chair mechanic. I do want to get into rebuilding my own stuff. I just bought a new house and want to build a garage so I can do this stuff. I printed out everything you said and Im a sponge on this stuff. I have a high iterest in learning how to do it. I have rebuilt a car engine with help.

What should I do now? I thought about buying a brand new engine for it. Cost... I was quoted around 2500 w/o labor of installing. This is as much a business question as a mechanic question. Do I find a new dealer/mechanic? Take this to Polaris Corporate? It only had 66 miles on the new piston. It has to be the quality work they did on it. I would like them to to fix it free! What do you think about that? The atv is only 1.5 years old. The atv quit on me the temp light came on the atv wouldnt start I replaced the plug there didnt appear to be compression on the pull start like arm breaking compression at the time like i've felt in the past when using the pull start. So I took it in immediately.The dealer looked at it and it wouldnt start. It sat in his shop 3 days and he just started it up without even touching the atv. He says it seems to run fine now. They havent even checked the atv out to see why it did it. I told them I didnt want it back until they knew what had happened to it. They are going to test drive it to see if it happens again. Maybe its just my exhaust pipe clogged I dont know.

This happended before on my old piston. It quit wouldnt start for a week then started for me lasted a week and burnt the piston. The dealer says that sometimes the cylinder wall gets scared causing it to halfway seize and that later it will run for a short period of time then completely seize. Is this true? You told me what causes this..several examples. What if they didnt give if more clearance for the wiseco? Like you mentioned and it seized up? Or if its runnning too lean or rich? Right now its not dependable. I just want a dependable atv. I ride by myself alot in eastern NC in swamp counrty and dont want to break down walking out 10 miles...with noway to get my atv out. you know what I mean?

I took it back to stock as much as I could to make it dependable again and this happens. Oh yeah, what about water in my fuel. My buddy thinks thats a possibility. Can you use a water eliminator on the 400? My buddy has had his 6 years never had a wrench on his Xplorer 400 and has 4000 miles on it. Its stock. Thats why I bought the 400. People told me 2 strokes werent as dependable (especailly honda guys) and I agree but his was and they are fast and the most universal atv I know of and I'm proud of it!

Man... the Honda guys are killing back home about my problems saying I should have bought a honda etc. One of em has a Honda foreman 450, he thinks his will pull mine down the road and kill mine in the mud. I'll smoke'em on the dirt road for sure. The 400 is good in mud too. I beleive mine has more clearance and HP than the 450 honda. Is that true? I like atv's and atv people in general and respect the honda but when they start ******* me just because I have a Polaris it sets me off and they know it.

Anyway, thanks for all the input you gave anymore would greatly help me in deaking with this situation on a business perspective as well as a mechanical.
Paul[img]i/expressions/face-icon-small-confused.gif[/img]Duck hunting spot where I ride.

 

Paulc, this is what I would do. I would get my quad home,buy a repair manual for it,get the tools you need (the manual will tell you the tools needed)and start to work on it checking and rechecking everthing.Take your time on it and if you get frusrated with it leave it alone for awhile then go back to it.A 2-stroke isn't bad to work on. You posted that it had no compression,so the first thing I would do is to check the head gasket to see if it has been leaking. Good luck on any road you take.

 

Boy Paul,

Too bad I am here and you are there. Basically you asked can an engine partially seized. Technically, no. Either it does or doesn't. A seizure is anytime a portion of metal gets soft enough that it scars or deforms itself. And it usually does the same to the surface it ran against. It doesn't have to stick. It could be a very some portion of your piston skirt has a "scuff" or "scratch" on it from ever so slightly "seizing", but yet it runs. They hardly ever run too long. Usually they start knocking or give some other abnormal behavior to indicate there is something wrong (ie. break the skirt off where the "scuff" was at, completely stick and lock up, etc...).

Sometimes autos have been known to get so hot they swell and when you turn them off they won't start until they cool. They may or may not have seized (scratch, scuff, stuck, etc...). I don't think it is possible on a 2 cycle, though. A 2 cycle has such a low tolerance for heat, they scar or scratch or stick solidly together.

If your piston seized, it most likely likely (90% of the time) did on the lower portion of the piston skirt. That is because pistons are larger there than by the piston dome. In other words, pistons are tapered from their dome (smallest) to their skirt (largest).

If you piston is seizing, it is from a few things:
1. It was set up too tight.
2. It isn't being cooled properly by it's cooling system.
3. Not enough or no oil in the fuel.


If you piston burns holes in it:
1. It is running lean.
2. It has poor quality fuel (water, etc...).

IMHO, I strongly prefer 2 cycles on atv's, motorcycles, lawn equipment, and boats. They are very simple, easy to work on, produce very good power and last a very long time. For example: All my lawn equipment is 2 cycle and 13 years old. I have never turned a wrench on any of them. Same with my boat, motorcycle and atv (although they are newer).

I have never ran anything but Amsoil 100:1 (mixed to 80:1) the entire time I have owned 2 cycles.

If you are sticking pistons and from your description of things, I would suspect the piston is not being setup correct. I dunno, though. If you have oil injection, then you have done all you can as far as the fuel mixture is concerned.

If you are burning holes in pistons, it is lean. Either jets, air leak, something.

But none of these things are a Polaris design thing. It is a operational (fuel/oil mixture, air leak, etc...) or setup (too tight of piston, poor cooling, etc..) thing.

I am assuming proper warmup is occurning and it isn't cold seizing. But I cannot help much more not seeing the situation.

Sorry

Chunky

 

I had something similar happen to my Scrambler. It would run then die and the hot light would come on. Then it wouldn't run for an hour or so. Then it would run again. I tore mine down and found the piston and cylinder walls scared pretty bad. The top of the piston on the exhaust side was melted. It was still running but seemed to be running poorly. My dads 500 Sportsman that weighs in around 800lbs could almost beat me in a drag. I found what I think is the problem. The shop that I had mill the head didn't put it back together right. The fuel line had been run right up against the cylinder. When I would ride, it would get hot and vaporize the fuel in the line. It would start to run lean and then vapor lock altogether. After an hour or so cooling down it would start and run but the damage was already done. It did this to me about three times. I just now tore it down. How it was still running at all is beyond me. I will make sure to do the work myself this time so I don't have to fix someone else's mistakes.

 

Would you recommend any repair manuals? Which one do you use?

PAul

 

Paulc I like to use the factory manuals,but I use some Clymer manuals also.

 

Yeah, I saw some manuals for the SCrambler specifically buit not for the Xlporer...they combined it with the sportsman manual and dont lisd the 2 stroke. Manuals like that get confusing. How can someone get a factory manual? Does polaris have them?

Paul