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So few months ago I acquired a 01 Explorer 4x4 (think its a 350 but not sure) 

Anyway the owner said it started reving very high, shut the key off and still kept running 

until finally he shut off fuel and it finally died. During the run away he said the exhaust got 

red hot and has melted plastics to prove it. Said some thing flew out the tail pipe, I kinda figured

it was the top of the piston. Anyway finally got around to looking at it (have a lot of other projects in the works)

and checked the compression, Shows about 40 psi. Can hear air coming out the carb while rotating the motor over. 

Gonna pull it apart eventually, don't hear any noises or binding in the stroke, You think the piston came apart? 

any horror stories of these and is it worth my effort and money? Don't really have any money in it yet. Thoughts? Az



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Ok, so not doing anything today so figured I would look inside.

Finally get the head off and actually looks good. Was expecting an exploded

piston. Got the cylinder off and that's when I saw the damage. Hopefully it can 

be bored instead of replaced. Do you thing it was starved of 2 stroke oil? The previous owner 

had removed the carb and tried to fix it and had problems after that. I did see the oil line was connected

to the carb and the oil tank is full so I am guessing. The damage looks like it had no oil but what do I know. 

Any thoughts? Az





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Wow ! That looks bad. Nice work on the tear down. It looks like a no oil situation, have you looked to see if the oil line is obstructed or not pumping into the mixture port ? Not familiar with that bike so I’m not sure if it’s pumped. My guess is the same as yours with a no oil in the mixture.  @06kfx440 has this bike and has done some work on it. 
maybe he can shed some light on this.    

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By the sound of what you just said, no oil is bad. I always run a 32:1 mix when I get a 2 stroke initially.
But even if the oil tank was full doesn’t mean it works. The way to check that it works is to run the machine and pull off the oil injector to watch it drip oil. I’d check the crank bearings and wrist pin bearings since that heads off

I’d replace the cylinder. It’s cheaper to buy new than to hone.
If money is a factor then replace the piston.
Run your fingernail across the cylinder wall and feel if it’s gouged.

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Ok. Definitely air cooled. From what I see it’s a 250 or even a 300. How did the oil look. If the piston and walls look that way then there is metal in the case and you will have to split the cases to clean it out. It’s really not a big job. I had mine out and apart in a hour

Call around to bike shops and see the cost to hone and bore. Then choose the route you want to take. Used isn’t a bad idea either. But new and oem is your best bet.

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  • 2 months later...

Well I took some time off, Finally got around to have it machined. Had to go .5 over and it cost me 128.00 for the labor. 

Then cost about 100 for the piston kit gasket etc. Installed the piston on the crank, was fun trying to manipulate the cylinder

on the piston and compress the rings while motor still in frame, kept running into frame, linkages, shifter etc. Finally after several

colorful words got it in there. 





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After all assembled, hooked up gauge gave it a pull and got about 125 psi by pulling

on the rope. Got it all back together and wouldn't run, found out he really screwed up the carb.

have gone through it several times, Got it to run but will only start with starting fluid. Once its hot it will 

stay running. Let it cool down wont start on its own. Have checked the choke system, raised float level till almost

floods. Still same problem. Installed larger jet and would run a lot better still no cold start. Raised the metering rod the highest

and it starts when cold but boggs out due to too rich condition at half throttle. 



I have tried the metering rod on every position. If I put it where it runs good it wont start when cold.

Finally I decided to tear out the starter as its bad anyway. While in there I replaced both crank seals as 

I have heard they can cause a lean condition and since im in there already...…… well you know, its all about

the fun. 


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Have it all back together, also replaced the supply line and filter from the 2 stroke motor reservoir and 

the tube from the pump to the carburetor. Seems like both were leaking. Took about a month to get 

those parts from Partzilla. I will see if it starts later. Finally have it mostly back together. Just have to turn 

on the fuel and see if it starts on its own. 

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  • 2 weeks later...

Update on the Explorer. After tuning the carb, jets, choke, etc also replaced crank seals.

finally got it back together and runs great. One other thing, while running it I lost the neutral/Reverse indicator light.

Thought it had to do something with the key switch which came loose but finally figured it out. Ended up being a 

loose connection on the connector on top of transmission, so if you get this problem check both those connectors. 


I only have about 250.00 invested in this thing, might keep it as its a 4 wheel drive and could

use it with my trailer for work around the property

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  • 2 weeks later...

Well today I said farewell to my Polaris. I know that thing inside and out but sold it today ended up getting 1700.00

for it so I wont miss it that bad lol. Had less than 300.00 invested but a lot of labor. Each one I do I learn something. 

And each one I like and would like to keep but the garage fills up pretty fast. I got one torn apart and plan on picking

up 2 this Saturday. Gonna keep me busy! Az

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Thats bitter sweet brother and i know the feeling. One thing i tend to keep in mind is the hours i put into it as well as parts. 

Question: What would you feel is a proper/fair hourly rate you would consider? 
And the amount of hours you put into each project ? 
I always keep track of my hours just for my own knowledge. 
Curious to see what you think. 

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I ran auto repair shops for over 23 yrs so I can relate. Something as little as crank

seals which were only 25 bucks but require a lot of labor. Same with piston etc. 

I always keep track of the money spent on parts, batteries and tires are the worst. 

as far as hourly rate I never gave it much thought as I do it to enjoy it but if I did 

I would figure in about 30 p/hr  The going rate is probably 60 - 100 at a stealership

and the mechanic never sees that kind of money. Az

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