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So this’ll be long I’ll give all the background first to see my issue skip to the ***
Hey I picked up a pit bike and a foreman for 800 the pit bike was running but the foreman was locked up. Sold the pit bike but when I took the top end off the piston I only found half a piston left. So knowing the rest of the piston was down in the crankcase I knew it had to be pulled and gone thru completely.
to pull the motor I went ahead and pulled the rear end off and unbolted the front diff to pull the drive shafts and pull the motor. Now I have the motor torn down completely and have all the parts of the piston removed. I know the rod and crankshaft is shot (heat discoloration and too much up and down play rod to crankshaft).
***so I’m wondering while I have the motor apart what should I check for? I know this motor died from heat as the oil in the head smelled like popcorn. So what should I check to make sure I fix the issue (overheating I assume) and not just the symptoms (blown up motor lol).
so put simply I don’t want to just rebuild the motor to have it overheat and repeat the process after 5mins of running
Here’s some pics
Below is a quote from a response to similar question from yesterday:
"Easiest thing to check is trash in the main jet. if it idles fine, then the idle circuit and low speed jet is clear. if it bogs off idle that's when it's transitioning to the main jet."
I will go ahead and open up the carb and check the main jet, but please respond to this post as if the main jet is squeaky clean.
Below is my post:
Only starts and runs on Full chock.
Does not matter what position I have my "mixture" screw. Tried it at zero, 1 turn, 2 turn, up to five turns. Spent a few hours confirming that the position of the mixture screw does not resolve issue.
Runs great at idle and if I slowly engage throttle, it will rev up as expected. But, quick rev up or when I am trying to drive it, it spits and sputters and looses power.
I also use a propane bottle and did not find any obvious leaks, and the vacuum port is hooked to fuel peacock and I also made sure to simply block the port with my finger to see if that would resolve the issue.
New Carb (after market), New Coil, Fresh Gas. No leaks at manifold boot, hot battery. Good gas flow. Runs too good to be a valve issue, or cylinder, great compression.
I can move the choke out a tiny bit, and it will still run, but will still bog down when I try to power it up.
I also have a 250 trail boss Polaris that I require to run at full choke, but it has power at all throttle potions.
I suspect it is running rich as the choke is on, but will not run with it off.
Any details would be appreciated.
By Dwight Williams
Ok, so I bought this scream of a deal the other day - a 94 King Quad 300 for $40.00. It's been sitting outside with no carburetor on it for about a year. Its rusty, missing some parts, wiring is all cut up and spliced etc. No seat, no racks but the plastic is all there minus the headlight housing. Anyway, who can pass up a $40.00 quad right? I get it home and looked at the sight glass for oil level, it's about 1/2 oil and 1/2 water. I drain it, refill it and turn the motor by hand (recoil starter is missing) and it turns over just fine. I worked on the wiring for about an hour and got it to turn over with the electric starter and got enough of it sorted out to get a spark. Did a quick compression test, 70 lbs. Wet test bumped it up to 90. Ok, so rings and cylinder washed out with water for a year, not too surprised. I thought 'what the hell' and sprayed some starting fluid in it and it ran for about 2 seconds - enough to show it's got life. Since then the compression has gotten worse, I can't get enough pressure to activate the carb diaphragm, therefore no fuel pump either. The compression is now around 60.
Anyway, my question is....is it worth it to try to get this thing going? I tore the top end down today and the cam and one of the rockers is pretty worn. I figured a top end job would be about $100 or so, depending on the condition of the cylinder but I'll probably have to put a cam and rockers in it as well. Doing some research on ebay I figure I'll have to spend about $500-$700 to make the whole machine right again. Much less just to make it run and use as-is but I won't really like it until it's right. I don't mind doing the work, I actually enjoy it but I'm concerned about what all that water did to the rest of the internals, I can't really test it all out until I can make it run.
I know it's a basket case but I'm not into it much at all, even if I do the top end and find something else wrong I'm still not out much. I'm leaning toward ordering the top end parts and going from there unless you can convince me otherwise - any way to check the rest of the internals without tearing it down? I plan on flushing the oil cooler before I do another oil change, I've drained it twice now and it gets milky almost immediately just turning the starter - I suspect the oil cooler is polluted badly.
I'll get some pictures today if anyone want to see them.
By Thomas Brooks
I know...I feel stupid for asking. I find it impossible to use the thumb throttle with my thumb when I have the bars turned full right. I have to reach across the top and grab the throttle from the front with my fingers. It isn't very smooth and I can't help but think that there must be a technique, mod or adjustment for this. How do I get past this?
2017 Polaris Sportsman 570 X2
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