I am a newbie to this forum, however, I have done my fair share of reserch for this ATV. My 5 yo son has a 03' lt50 and he is about through with it. At this point I dont want to upgrade to a bigger machine due to the fact that I just bought it last christmas and I don't think he is ready to understand the fundamentals of "shifting". The 50 is a perfect "fit" for him, I just think it needs more power. I bought it used last year and it is still in mint condition. Last weekend I decided to remove the restrictor in the exhaust but it looked like it had already been removed. I did not get into the intake yet. I removed the carb and noticed a "55" jet piggybacking another. I removed the piggyback (very reluctant due to the fact that the other jet looked like I could fit a pencil through it) and fired it up. It ran very fast at idle until I gave it some throttle then it just bogged down and died. Since this was being done in the "field" I wanted to make sure it was more reliable than fast so I put the piggyback jet back on, drilled some holes in the filter box and rode the rest of the weekend. My questions are this: I am going to purchase the CT racing head/exhaust combo. After that what jetting am I going to need (size wise) which jets need to be removed or replaced, #2 what is the mod regarding the carb slide? I haven't heard enough about this one to fully understand. #3 is there a clutch mod that works or even be found. What else can I do to obtain more low/top end power. I see they have a set of 5 paddle haulers for this machine but after seeing my son not even able to ride it onto the trailer without having a 5 block run at it I can't possibly see how paddle tires are even functional. is there a list of mods (in fundamental order) that can be found or explained. I have seen so many mods but they all breifly explain what to do. I would like to know in order of importance so as not to ruin another great weekend with my son. Thank you.

 

<div class="FTQUOTE"><begin quote>Originally posted by: dunerdad
I am going to purchase the CT racing head/exhaust combo. After that what jetting am I going to need (size wise) which jets need to be removed or replaced
</end quote></div>

We've got an 03 LT50A. Personally, I wouldn't waste my money on the CT kit. I have the stock head milled .030" to up the static compression. There is a noticeable gain in low-end power. Total cost around $20. I'm running a 70 main jet w/ removed piggy back pilot jet. I drilled several 1/2" holes in the airbox as well. Heat up the intake and pop out the restrictor. While you're in there, clean up the casting a little bit and smooth the transition out inside where the restrictor used to be. I used JB weld and then contoured it for a smooth transition. Also remove the head pipe restrictor. I remove the spark arrestor and cap too.

<div class="FTQUOTE"><begin quote>Originally posted by: dunerdad
#2 what is the mod regarding the carb slide? I haven't heard enough about this one to fully understand.
</end quote></div>

If you look through the carb body while holding the throttle wide-open, chances are you will see the carb slide is still hanging down inside the main body. You can carefully grind the TOP of the carb slide to allow it to fully expose the main body. Do NOT grind the BOTTOM of the slide. Also make sure there isn't any slop in the throttle cable itself. Use the cable adjuster to eliminate play in the thumb throttle. It's located under a rubber boot on the throttle cable on the handlebars.
</end quote></div>

<div class="FTQUOTE"><begin quote>Originally posted by: dunerdad
#3 is there a clutch mod that works or even be found. What else can I do to obtain more low/top end power. I see they have a set of 5 paddle haulers for this machine but after seeing my son not even able to ride it onto the trailer without having a 5 block run at it I can't possibly see how paddle tires are even functional. is there a list of mods (in fundamental order) that can be found or explained. I have seen so many mods but they all breifly explain what to do. I would like to know in order of importance so as not to ruin another great weekend with my son. Thank you.</end quote></div>

I couldn't find any springs to fit, so I took the next best alternative. I lightened the clutch weights. I drilled about 6 or 7 1/4" plugs into the each side of each weight. The more material you remove, the more rpm it takes for clutch engagement. This is a trial and error process. I raised the clutch engagement about 500 rpm.

After doing all of these mods, this little 50 can pull my 245# around the yard easily.

 

My fear with milling the head is this. When I took the exhaust off I noticed that the restrictor was missing. As I said earlier, I bought the bike used, so, if the previous party had some mods done that may have gone unnoticed by me I do not know. I can not find a manual anywhere under $70 so I never purchased one. Now, regretably I have no head torque specs, factory compression (needed to make sure head has not already been milled.) or even factory spark plug info. Speaking of which....Do I need to apply a different heat range if I am going to mod the head? Also, I have read 2 different mods now on the carb slide. The first was a plastic "stopper" of sorts that kept the slide from opening completely, now this where I need to grind material from top of slide. This is where I am not quite understanding. Are there specific years that require grinding vs. removing a plastic part. I don't wish to break out the dremell unless I am pretty sure its gonna work. Going to the dealership usually means alot of explaining to my better half. Again, Thanks for the info...

 

Another Thing That is still a little unclear is the pilot jet vs. the main jet. In my specific example There is a smaller jet screwed into the top of another jet or "piggybacking". The smaller jet piggybacking the larger jet is stamped "55"
is this a factory jet? Also, I keep hearing that this smaller jet refered to as the pilot jet! Yet the bottom larger jet is the main jet? I guess I need to be certain of this. Wouldn't it make sence to just up the size of the "55" to a larger jet since it does in fact piggyback the lower jet. By increasing diameter you gain flow through both?? I did not find a size # on the lower jet however, As stated in previous post It has a substantial hole through it. I have 2 banshees that both run #310 mains, by comparison I would have to put the lt50 at around a #500 main. Again, I am a little unclear so any info would be greatly apprecialted.

 

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

My fear with milling the head is this. When I took the exhaust off I noticed that the restrictor was missing. As I said earlier, I bought the bike used, so, if the previous party had some mods done that may have gone unnoticed by me I do not know. I can not find a manual anywhere under $70 so I never purchased one. Now, regretably I have no head torque specs, factory compression (needed to make sure head has not already been milled.) or even factory spark plug info. Speaking of which....Do I need to apply a different heat range if I am going to mod the head? Also, I have read 2 different mods now on the carb slide. The first was a plastic "stopper" of sorts that kept the slide from opening completely, now this where I need to grind material from top of slide. This is where I am not quite understanding. Are there specific years that require grinding vs. removing a plastic part. I don't wish to break out the dremell unless I am pretty sure its gonna work. Going to the dealership usually means alot of explaining to my better half. Again, Thanks for the info...</end quote></div>

Stock compression is around a measly 5.6:1. You should be able to look at the bottom of the head and see if it's been milled. You can switch to the cooler "6" plug instead of the stock "5" heat range.

Some carb slides have the plastic stopper in there, some did not. Mine did NOT have it, so I ground the top of the carb slide.

 

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

Another Thing That is still a little unclear is the pilot jet vs. the main jet. In my specific example There is a smaller jet screwed into the top of another jet or "piggybacking". The smaller jet piggybacking the larger jet is stamped "55"

is this a factory jet? Also, I keep hearing that this smaller jet refered to as the pilot jet! Yet the bottom larger jet is the main jet? I guess I need to be certain of this. Wouldn't it make sence to just up the size of the "55" to a larger jet since it does in fact piggyback the lower jet. By increasing diameter you gain flow through both?? I did not find a size # on the lower jet however, As stated in previous post It has a substantial hole through it. I have 2 banshees that both run #310 mains, by comparison I would have to put the lt50 at around a #500 main. Again, I am a little unclear so any info would be greatly apprecialted.</end quote></div>

The stock MAIN jet is a 55. It is located in the center of the bottom of the carb. The pilot jet is directly next to it. This is where the"piggy-back" pilot jet is screwed into the pilot jet. They're stacked. The main jet needs increased to at least a 70 after doing all the mods. The pilot jet effects the idle & part-throttle fuel circuits. The main jet is for WOT.