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Discussion Starter #1
I figured I post this in hopes of some ideas from more experienced members.

I would like to add that I'm following a few other threads with similar issues but don't want to hijack their threads.

So, I have a 1987 trail boss 250 r/es that I got from my father in law. The plan is to hopefully get it running for my son. It sat for 13 years.

What I've done so far :

Cleaned the gas tank and oil tank.

Replaced the fuel line/filter and oil line

Since I figured the carb was gummed up (and it was) I bought a used carb off of a 93 250. I also needed the throttle/choke cables. Although I'm unsure if the choke works.

I can get it to start and idle, at this point that's it. I do have the exhaust off to check for mouse nest. If I try and give it any throttle is bogs out and most time stalls. After it sits for a second it pukes gas out the overflow/vent.

I do have a carb rebuild kit coming Saturday.

So plans for this weekend. Carb is coming back off. Clean and replace probably the needle and jet. I did have the bottom off yesterday to inspect the floats. Swapped floats from the original to the replacement carb. The originals seamed to move a little better. Replace the spark plug. ( Still have the original in for testing purposes). Put the exhaust back on. And see where that gets me.

I haven't tested compression yet. Picking up a tester tomorrow.

For now I have clear fuel line's just to monitor it. I noticed that at any given point that there is a air pocket that's about half the length of the line, is this normal? I'd assume that the line would always be full.

Any Input is greatly appreciated.


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Air in a new line is common and it won't hurt anything - fuel will flow right past the bubble and over a long period of time it will purge from the line. Similarly, air in a fuel filter will not affect the flow or function.
 

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Discussion Starter #4
Here's a quick video of it running and trying to throttle up




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It will not run right without the muffler and air box, but test the lack of fuel possibility by spraying starting fluid in the intake as the throttle is opened - with no air box and filter, use extreme caution and have a fire extinguisher handy - a backfire from the intake or flame from the exhaust will ignite starting fluid instantly - the fire will be short lived, but it will cause a lot of excitement and possibly the loss of some hair if your are too close.
 

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Discussion Starter #6
It will not run right without the muffler and air box, but test the lack of fuel possibility by spraying starting fluid in the intake as the throttle is opened - with no air box and filter, use extreme caution and have a fire extinguisher handy - a backfire from the intake or flame from the exhaust will ignite starting fluid instantly - the fire will be short lived, but it will cause a lot of excitement and possibly the loss of some hair if your are too close.
I had seen some comments on other threads referencing not having the air box on will affect how it runs. I remember hearing somewhere that not having an exhaust on a quad it will not run right either.

I'll get the muffler back on and put the air box back on hopefully tomorrow and see how it runs.

My rebuild kit won't be here until Monday now so this will give me something to do.

I appreciate all your help and insight.


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Discussion Starter #8
I put the exhaust on. I can get about 1/2 maybe a little more now before it wants to bog down. I didn't put the air box on today. Tomorrow I'll toss it on and see what changes. Also thru a new spark plug in. The idle is still slightly rough. I have the small screw 1 1/2 turns out. It sounds like it may have a small skip or miss fire.


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Discussion Starter #11
I was able to rebuild the carb and get the choke free and moving. Waiting on a new throttle cable so I can fire it up. I also ordered a cheap ebay carb as a backup if I can't get this carb working correctly


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Discussion Starter #14
New throttle cable came in today but only had time to install it in the carb before I had to leave for work. Hopefully either Sunday night or definitely Monday will be able to get it installed and fired up. I did clean and rebuild the original card using parts from the replacement carb (they were in a lot better shape then what was in it) just for something to do. New carb will be here tomorrow. Will have that as a "just incase" replacement


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Discussion Starter #15
Update

China carb didn't make it Saturday. Hopefully tomorrow.

Was able to install new throttle cable and rebuilt carb. Installed airbox. After a few pulls it fired up. Let it idle for a few minutes and gave it some throttle. No bogging no hesitation. Shut it off installed the gas/oil tanks back in there normal spot, took it off the jack stands and went for a spin. Ran great for a couple of minutes. Noticed the exhaust was getting smokey then started loosing power. Could only limp it back in the garage. It would start to sputter when I gave it more than 1/4 throttle. Let it sit for about 2 minutes fire it up and would be fine for a couple minutes then would do the same thing. Pushed it in the garage fire it up and can throttle up no problem. Messed with the carb adjustments a little but am at a loss at tuning. I'm assuming it needs to be adjusted


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Wondering if the coil may be bad. Fine when cold, but produces pretty weak spark once it heats up and build resistance, thus not getting full combustion and flooding the cylinder.
 

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Discussion Starter #17
Wondering if the coil may be bad. Fine when cold, but produces pretty weak spark once it heats up and build resistance, thus not getting full combustion and flooding the cylinder.
It's a possibility. I'll pull the plug tomorrow and check to see what it looks like. Try get voltage reading cold and warm.


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It's a possibility. I'll pull the plug tomorrow and check to see what it looks like. Try get voltage reading cold and warm.


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You're not likely going to get an accurate voltage reading on the secondary side of a coil with a meter...it'd take like a $40k meter for that. You'll want to ohm out the coil cold and again when it warms up...shouldn't be much change in resistance...if there is a significant change, then it is an intermittently failing coil
 

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Discussion Starter #19
Here's where I'm at. Haven't tested ohms yet wanted to test it again. Here are a couple video's. From the smell of the machine I feel like it may be too rich. I believe that I set the clip on the center notch of the needle. I think raising it one notch would help lean it out. Not sure what screw on the carb would help with it. Also when I tried to drive it I barely made it out of the garage before loosing only being able to use about 1/4 throttle under load

1. Cold idle


2. After idling for 30+ seconds can get about 3/4 throttle before it's bogs out.


3. After less than a minute drive



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