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Discussion Starter #1 (Edited)
A little background on myself: I am 47 years old and a master electrician. I have been a shade tree mechanic since I was a kid. I have always had old Farmall tractors, 50s-70s chevy trucks, old motorcycles and three wheelers, but never a 4 wheeler.

I have a 7 y.o. daughter and she expressed some interest in a 4 wheeler, but instead of going out and dropping $2k on a new japanese model, a while before Christmas I picked up a Honda clone 110cc chinese ATV of off the local C list for $50. It needed the carb cleaned and I got after the bad wiring harness with a pair of side cutters and eliminated all but the essential wiring and got it running for her. Shortly soon after, I tired of running alongside her, so was on the hunt for a wheeler of my own.

Just after Christmas, I picked up a $500 package deal on a complete 02 Rancher TRX350TM, (Rancher #1) and enough parts from an 02 and 03 TRX350TM to make another (Rancher #2) and have spare parts (including engine) left over (03 frame rusted out and someone cannibalized the 02 for some reason). I am trying to get the "complete" Rancher #1 going. I got it from a 16 y.o. kid who couldn't figure it out. The story I got was someone had redone the top end (overbore with new piston and rings a short while ago. He couldn't get it to run and advertised it as needing a battery and starter solenoid. Someone had recently installed a new knock off carburetor, but the oem keihin carb was MIA. I was able to charge the AGM battery with the AGM charger I have. It still wouldn't crank and I diagnosed it as a bad neutral indicator. I worked around this (temporarily) by grounding the green/ red wire from sensor. The bike would crank and try to run but sputter. I installed a new spark plug, drained the old gas, added fresh gas and removed the carb, cleaned the jets and passages with carb cleaner air and a tip cleaner I use for my cutting torch. The carb really didn't seem too dirty. After this it ran a little better, but still not well enough to even try and put it in gear. Since I was going to need a carb in order to try and get Rancher #2 running, I went big and spent $30 on a knock off carb through Amazon. I figured I would give it a try on Rancher #1 first. It runs better, will idle, but still stumbles and stalls when I give it throttle. I wonder if I should tinker with the idle mixture screw some. I didn't even think to check where it was set when I got it. Does anyone have any advice on getting this thing running? I am hoping it is a car/ fuel issue. I will be doing a compression test soon if it seems to not be fuel related.
 

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Welcome to the forum.

Let's see what help we can offer. Your work around on the neutral light is what I would have suggested doing until you get the bugs worked out, then fix it properly.

First thing to do is check the compression - if the compression is good and you have one that runs well, take the carb off the running one and put it on the project one - if that fixes the project one, you know the carb is the problem.

The fuel screw is for idle only - it is set about 2 turns out from lightly seated - once the engine is started and warmed up to normal operating temp, the screw is then adjusted for the smoothest idle.

Not knowing the ability of the engine rebuilder, you might have to take the top end of the motor apart to check the cam timing, but that's if the compression is low or high or the engine fails to run with known good parts. If you need a manual, I have an 04-06 TRX350 copy in PDF I can email you.

Let us know your progress.
 

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Thanks for the reply. The trouble is neither of the atv's is running. I started with the best of the two, which is still less than good. The other is a big pile of parts. I plan a compression test this weekend. Anyone have any idea what the compression should be?
 

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Discussion Starter #4
I did a compression test and came back with 115 lbs. on Rancher #1. It seems kinda low. While I had the tester out, I ran a test on the Rancher #2 and it showed 120 lbs. (?) I am waiting on a starter solenoid and a new intake manifold for it and hopefully will have it up and running soon. I fiddled with Rancher #1 and didn't have any better luck getting it to run...
 

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Depending on the gauge used, cranking speed, valve clearance and whether the throttle is closed or held wide open (should be held wide open), 120 to 150 is considered normal
 

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Depending on the gauge used, cranking speed, valve clearance and whether the throttle is closed or held wide open (should be held wide open), 120 to 150 is considered normal
I held the throttle wide open when running the compression test. When I pulled the new plug I installed to run the compression test, it was very fouled looking. Not oily like bad rings, but black and sooty like it was too rich. (?) I wonder if the rings have ever seated. I don't think the thing has ever urn long enough to do so... I also have to wonder if the top end repair involved any work on the valves, causing the low reading when checking compression...
 

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All valid possibilities, but the compression is adequate to get an engine started and running - if the rings are not seated, some run time will take care of that - there's no difference in the motor of a motorcycle, three wheeler or 4-wheeler - they all have valves, a cam, a piston, a crankshaft, an ignition and a spark plug - they all require the same ingredients to perform.

Take the carb off and spray starting fluid (I use contact cleaner) into the intake - if the engine starts, revs up and then dies, you probably have a carb problem - if you cant get to fire on starting fluid, it probably has an ignition problem - the other things are totally mechanical - compression is good, the valves have the correct clearance, the cam and rocker arms are in good condition and the cam is in time - all that is left is spark at the right time and fuel and air in the right ratio.
 

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Discussion Starter #8
All valid possibilities, but the compression is adequate to get an engine started and running - if the rings are not seated, some run time will take care of that - there's no difference in the motor of a motorcycle, three wheeler or 4-wheeler - they all have valves, a cam, a piston, a crankshaft, an ignition and a spark plug - they all require the same ingredients to perform.

Take the carb off and spray starting fluid (I use contact cleaner) into the intake - if the engine starts, revs up and then dies, you probably have a carb problem - if you cant get to fire on starting fluid, it probably has an ignition problem - the other things are totally mechanical - compression is good, the valves have the correct clearance, the cam and rocker arms are in good condition and the cam is in time - all that is left is spark at the right time and fuel and air in the right ratio.

I fooled with both Rancher #1 and #2 some this past weekend. Rancher #1 is still giving me the same fits. Idle only with either car I have. The weekend before, I already verified that Rancher #2 will start with carb removed and starting fluid sprayed in intake, but will not run with either carb. (If you recall, it has more compression than Rancher #1...)??? Is it possible that I have too bad carbs? I believe it is highly unlikely, but facts don't lie... I ordered a new knock off coil last week, and it is supposed to be here today. If so, I will try it tomorrow. If not, I am going to try swapping the ignition coils between the two bikes...


On a related note, does anyone have a source on a reasonable priced new carb? I have one OEM carb, but it is in such bad shape... It is actually rusted shut and the throttle won't even operate! I am going to disassemble it as far as I can and try soaking it this weekend.
 

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Discussion Starter #9
On Rancher #1, I am going to pull the side cover bolt in order to verify that it is at TDC. I have done similar projects where I placed something like a zip tie of straw into the spark plug hole to verify that the piston is at TDC. I suppose I will need to remove the rocker cover and check the valve adjustment. I forgot to look and see if the head looks like it has bee replaced or refurbished or not. The jug is very clean, as if it has been replaced.
 

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Discussion Starter #11
Success! I got Rancher #1 running! Since I only had one intake boot a the time, I was swapping it between bikes (my new intake boot has since arrived). During the last swap, I was keeping an eye out for anything out of the ordinary, and notices that the o-ring was pretty well compressed flat. As a quick fix, I smeared a little grease on the o ring to help it seal. It seemed to do the trick. I haven't ridden the quad yet due to the fact that the brakes are completely frozen up. I placed a few orders and I am waiting on brake shoes. all four wheel cylinders, and a new rear pivot pin. If I have time today, I plan to install the new intake boot on Rancher #2 and see how it goes with it. Ironically, the front brakes appear to be operational on it. Not sure about the rear brakes yet, though. Thanks for the help!
 

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Discussion Starter #12
On a funny side note, my 7 y.o. daughter already named the quads. They are "Cool Rancher" and "Jolly Rancher"! Not sure which is which though...
 
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