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Just picked up a 95 Polaris trailblazer 250, needs a little work but he’s pretty stoked

Thanks, I am new to the ATV scene as well. Bought a 2017 Arctic cat a month ago, now the wife wants one. I am pretty handy with a bunch of tools.

so . . I recently purchased a 2022 CFM 800. My experience so far has been pretty good, both with the machine and with parts I elected to buy, other than service parts. I have not had any issue obtaining service parts and I believe that availability is growing. I do know some people have had issues, and a good bit of that sounds like individual dealers rather than the manufacturers. I've had no real issues with the machine or with doing the maintenance on it myself, either. I am new to ATVs so I can't really say much in terms of comparison, but as a long time "DIY person" (and pretty good) and a pretty sound mechanic its a straightforward machine and pretty user friendly in terms of basic upkeep.

chain is tight, didnt see any strange behavior on the way the rockers were moving while doing compression tests with rocker covers off leakdown test showed minor leakdown past rings. minor. valves tight id say the rings are slightworn yes but down on a bit of compression/power is really different than it coughing and sputtering at high rpm this quad starts instantly, purrs like a seeing machine, and blows zero smoke. im doubting compression now. i have a second “parts” moto4 and decided to test the ignition coil of it vs the current patient. to my surprise on the patients sparkplug wire/coil, i was reading open from the coil orange wire to the spark plug connector. meanwhile the parts read 10.75 kiloohms. so i swapped them. installed a new petcock in the fuel tank and just sat it on the frame. After some minor carb tuning it ran like a sewing machine. So.....i will take it out for a rip tomorrow but im thinking....compression is a bit down yes. But thats red herring. i am thinking the sparking was jumping inside the wire from the ignition coil to the plug. somewhere there mist be an open because i could not get a resistance reading out of it. that may explain the high rpm sputtering. faster spark and the jumping of hypothesized gap crossing made the timing off. thats my theory and ill know more when i get a chance to drive it tomorrow. also i cant rule out the weirdness of the compression incremental rise. yes if i keep going with the starter it maxes at 75-80 psi. if i then bump the starter several more times it randomly adds compression up to 120. strange!

If the oil made no difference then it points to the valves.. Sticky in the guides, badly worn cam, play in the cam bearings, play in the timing chain, carboned up valve heads(except that doesn't happen these days), something blocking the exhaust, like a flap of rusty pipe inside, It is sort of normal for compression readings to climb on each compression stroke, up to about four or maybe five strokes, then after that you might get an extra five pounds if you are lucky.. But you've done plenty of tests, and know that one right, and this is different in that it doesn't build up if you just keep your finger on the button. You have to let it get another breath between cranks.. Right ? I'm just trying to get this clear.. Not enough lift on the inlet valve.. ??

I tried the oil down the spark plug hole trick and got no change. tried a different test with same result. im trying a leakdown test to see where the air escapes. absolutely zero smoke. none. AND it starts easy as pie. will also run a borescope in but i wont be able to get it to turn around and face up at the valves.

Hey guys! Stoked to be here because ive found its pretty hard to get help for mini quads I recently bought a mini quad (it's a piece of poop so i have no clue the make) and it ran perfectly fine. I was running it a few weeks ago all day and it worked fine and the next day when i went to start it, the kickstart bar was super hard to push down but i could still do it, then it would skip and finish off hard to push down. I have fairly intermediate mechanic abilities so i was able to pull off the cover and start playing around. it seems the kickstart spring is fine but i noticed a bunch of metal shavings. long story short i posted pictures and took a video of how things are kind of running. i assume the gears started grinding and now they wont catch fully, hence the skipping? Also, im aware the main gear on the left has broken teeth, i found out the hard way when i tried to take off the nut and the teeth broke. IMG_7447.MOV IMG_7445.HEIC IMG_7446.HEIC

Due to the age of the machine and the reputation of abuse these engines get I agree with mech it could very well be the rings, but it could be a combination of worn rings and leaky valves. If the rings were worn bad enough to cause this problem it should be smoking a lot. Always check the compression with the throttle completely open. If this happened to me the first thing would do would be try a different compression tester, I have not had good luck with testers accuracy. You said the more you tested the higher the compression would get so the more rotation the more oil is getting pumped through the system and would also point to rings, but because of the popping and backfiring I would think leaky valves, there could be carbon deposits not letting the valves close completely, I would suspect the exhaust valve. You said that when it gets hot it won't start that does point to low compression or flooding . Maybe do a compression test when it won't start hot and see what you get. Just my thoughts.

A compression that climbed over a succession of compression strokes used to be attributed to weak rings. If you have a vacuum gauge you could check the readings.. If you put about a teaspoon of engine oil down the sparkplug hole then check the compression it should go up quite a lot.. Sticky or leaking valves don't get improved by oil down the bore, rings do.

Sweet, just bought my son (7) his first four wheeler a few day ago as well. Hes still puny, can hardly even turn the wheel. Been riding on back with him and having him go slow, pretty sure ive been jarred back and forth from the throttle to pressing the breaks more than a teenager trying to learn how to drive a 5speed. Lol