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Trail boss need help!!

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6.7K views 19 replies 9 participants last post by  LATEBURD HERE 2 HELP  
#1 ·
My 1990 trail boss 350l 2x4 starts and idles fine but when you go to rev it up it bogs! It will not move! I just cleaned and rebuilt the carb and jets, put in new air filter, and added new gas. After I put it all back together i still had the same problem. I then checked for a vacuum leak and that came up as a negative as well! I'm stumped. It ran absolutely perfect then I loaded it up on the trailer to take home from the cottage and it hasn't ran right since! Please give me any advice!! This is my first Atv and I've only rode it for aprox 6 hrs! I don't want this to ruin my Atv experiance! Please help thanks!
 
#5 ·
Thanks and it will rev just a little bit sometimes but not all the time then it bogs and no it will not rev in low high rev or neutral. I'm just out now getting a new plug has shut off valve and new gas lines and see how that works but I'm doughtful. Also going to do a compression test tonight as well I'll let you know what happens with those but do you have any idea what the problem could be ? Thanks a million
 
#6 ·
Could be the plug or weak coil.Especially plug if its a 2 stroke.Wouldn,t suspect the coil...If the plug doesn,t do it could be starving for fuel,plugged fuel shutoff,dirty passages in the carbs(some you have to soak or sonic clean them...Could even be a plugged exhaust if was sitting for awhile outside...Critters love building nests in the pipes,especially effect 2 strokes.Bad reeds but I doubt it.

key is to determine whether its a fuel,ignition or engine problem.A fuel problem is easy to determine.

Let me know whether 2 stroke or 4 and 2 stokes have some other things as well.Wouldn,t be the first time a simple plug fixes it.:)
 
#8 ·
I don't think it's an exhaust problem stored indoors almost all the time. Really hoping the plug fixes it I'm not sure if it was ever replaced since it is a little bit of a pain to get to (its under the gas tank), and it was dirty. Anyways I'll let you know how the compression test goes and hopefully I'll be able to find a new shut of valve as I had no luck tonight. Keep you posted! Thanks a lot
 
#12 ·
I don't know if this is true, but when I purchased my 250 Trail Boss in 95 I was told by my dealer that as a rule of thumb it should have the cylinder redone about every set of tires. I cannot verify this as my Trail Boss is still running strong. How ever it does now misfire and blow the exhaust pipe off of the flange every now and then. I sold the 250 last year to a friend and still get to work on it from timeto time.
 
#14 ·
Remove the head. then the jug should come off of the crank case so you can have the cylinder rebored. Then replace the piston and rings with a .020ths over piston. (it been almost 18 years since i have done one) Then just reassemble. Not a terrible job just make sure you get all of gaskets and torque specs and torque sequence.
 
#15 ·
The other suggestions to narrow down the problem to either spark or gas were good.

If you pull the gas line off at the carb, do you get good gas flow?
Is the carb set to stock settings?
Is the airbox attached and sealed?

If all of the above are good, then start looking for electrical.

Do you have a multimeter?
There should be specs available in the service manual that you can use to check individual components rather than just replacing random parts one by one.
 
#16 ·
A lot of times on a two stroke you don't necessarily need to bore it. Some times you just need to hone the glaze off and put in a new ring set. You have to determine the condition of the cylinder before you can decide. Two strokes are pretty simple but some small things can cause big problems. Even a build up of carbon deposits on the piston or head can create running problems.

Every time you replace the tires seems a bit much.