I have an 03 lt50 that has since got me pulling my hair out. I have read many posts regading this machine and in hind sight should have never made the purchase. Anywho... I made the complete CT purchase (pipe, filter, head, jetting)and have done further mods as well. I shaved the carb slide, pulled both restrictors, moved the needle clip the the middle, removed the oil injector etc. After everything was done I completely cleaned the carb and the bike ran fine with a little hesitation mid throttle. After going through the jets multiple times I realized the air screw/ idle screw looked to be switched (I bought the bike used)
So I looked at the schematic on bikebandit.com and it shows the slotted screw on the right and the hex screw on the left. If this is the case and you completely screw the hex screw all the way in it will hit the jet needle. Anyway, moving foreward, I put everything together just as the schematic shows and the bike ran flawlessly, I took it to the dunes this weekend and my son could go places he could never go before. After about a half hour I noticed the bike would just shut down. I thought he was bumping the kill button but after following him around it would actually shut off about every 5 minutes. And when it would run it was definately losing power. It would still rev up to full RPM but just did not have the power to go up hills he was just going up 15 minutes earlier. I took the bike back thinking the air filter was clogged. It was not. I let it sit for about 3 hours and tried to take it out again, now it wont start. I took the bike back home, pulled the plug( chocolate color) completely cleaned the carb removed the head to see if I burned a piston (did not) I cannot figure out what is wrong. The plug is dry after about 30 pulled so I do not think it is getting fuel. I checked the compression( 140-145) has good spark, I am just completely baffled. If anyone has a suggestion I am listening. At this point as soon as I can get it running It is outa here!! I am running the CT kit 32:1 race fuel, 75 main, stock plug, jet needle in middle position. Hope this helps. Also, can anyone tell me which position either of the the two air/idle screws they are supposed to be in and approx. how many turns OUT I should start. I am at approx 900 ft. elev. at about 40 degrees

 

Are you running a fuel filter? Could be junk in the tank, fuel line, petcock, etc. Remove the fuel line from the carb and turn petcock to PRI (prime) position. Fuel should be coming out of the line.

BTW, we have the exact same quad for our kids. I did all the basic mods + lightened clutch weights. Saved the money from CT kit and put that towards our Scrambler 90.

 

Plenty of fuel coming from tank. yet plug still dry as a bone.

 

Then the problem is in the carb or intake manifold. Will it run on PRIME position?

 

OK....I just spent the last 3 hours on this bike AGAIN. I completely went through the carb again. Cleaned in solvent, blew dry, replaced. I put a latex glove over the air box to make sure there was vacuum.(there was) replaced both hoses on the tank. AGAIN nothing. BUT....When I remove the spark plug to check spark, It is great. I replaced the head gasket (155 psi) When I hold the spark plug to the hole really close and pull the starter it flames out and backfires. When I put the plug back in...NOTHING. I took the tank off, cleaned it checked both prime positions and flow is great. I even disasembled the shut off valve in the carb and cleaned it. There is definate fuel flow to the carb, I removed the bottom screw from the carb and let it flow for about 2 minutes and had nothing but continuous flow. If I spray fuel into the carb and pull start...NOTHING. If I spray directly into the cylinder...NOTHING. IF I spray into the cylinder and hold the plug just short of the hole it will flame out and backfire depending on the proximity of the plug to the hole. This one definately has me by the short and curlies...

 

<div class="FTQUOTE"><begin quote>Originally posted by: moomba99
I replaced the head gasket (155 psi) When I hold the spark plug to the hole really close and pull the starter it flames out and backfires. When I put the plug back in...NOTHING</end quote></div>

I ran out in the garage and did a compression test on ours. Stock bore, .020" milled head, I get 130 psi with WOT.

Have you checked to see if the timing is still correct and hasn't moved?

 

if there is still a problem must be reeds.

 

If you have spark, fuel, and air the engine should turn over, at least for a moment.

You're getting spark. You're drawing air. You're getting fuel to the carb. But you don't know for SURE that you're getting fuel into the *cylinder*. In fact, you have a dry plug... not a good sign.

Try squirting some fuel into the plug hole, replace the plug, and try to start it. If you have air and spark, that fuel should ignite and you'll hear it. If this works, then you know you're not getting fuel into the cylinder.

We have a 2002 LT-A50 and our son absolutely LOVES it. It goes everywhere and is as bulletproof as anything we've ever owned. Don't lose hope... it's worth fixing yours.

Report back!

 

I have sprayed fuel into the carb and nothing. I have sprayed directly into the cylinder and nothing. When I spray directly into the cylinder put the plug back in and pull 8000 tiems still nothing. However, If I spray directly into the cylinder and leave the plug out holding it just against the hole it will ignite the fuel and depending on how close I hold it to the hole it will make the bike backfire. I thought I knew everything there was to know about 2 strokes until now. Where would the reed cage be on this thing. Threr is nothing but a small adaptor that connects the carb directly to the cylinder. While typing this out it does seem to me that if it is firing while plug is out of cylinder but not in, to me that would mean no air to cylinder BUT when I put a latex glove over the rear of the carb and pulled the starter it definately draws into the carb.

 

<div class="FTQUOTE"><begin quote>Originally posted by: onebigzj

if there is still a problem must be reeds.</end quote></div>

These don't have reeds.