Here's what I did to my daughter's suzuki lt50 quad. Same motor as the jr50. I started by removing the restrictors in the intake manifold and checking to see if the exhaust restrictors was still in. It was already removed as was the baffle in the end of the pipe. I pulled the carb and removed the first pilot jet. (There are two. One stacked on top of the other.) the one down deeper in the carb stays in. It actually seem to be just right. Next, I put in a wiseco 2mm oversize piston kit, milled .040 off the head and cleaned up the ports. I gasket matched the intake to the head, cleaned up the exhaust port and opened it up a bit. I also gasket matched the transfer ports at the base of the cylinder. That almost doubled the size leading up to the ports. I haven't done any jetting yet and have only run it for a few minutes in the shop but it definitely has more power. I was able to get it to overpower the brakes. I'll ask my dealer if he can order jets for it and try playing around with that to get optimal performance for the work I have done. I might pull the pipe and see if there is anything that I can do to it to make a little more power. So far I have about $400.00 into this project including the $100. Purchase price of the quad itself. I did order various jets and started by switching to a #62.5 (stock is #57.5) it helped with power but not enough. Took it out and put in a #65. It was much better but still not good enough.i currently have a #67.5 in it and with the rear wheels off the ground it revs up like a chainsaw. Tried it in the driveway and it'll lift the front wheels slightly. I still have a #70 main jet to try, but for now it seems ok. I'll let the kids try it out and see how it goes for them. There is still room to mill more off of the head if I want to but it seems pretty good for now. ( I put clay on the piston with the head bolted down just to make sure the piston wouldn't hit. There is enough room to easily take another .005-.010 off if I choose to. Milling the head is probably the best bang for the buck. If I remember correctly the stock compression ratio is an enemic 5.6:1. I'm no math whiz but I'm guessing I must be closer to 8.5-9:1 comp ratio now. Mike.

 

Remove silencer, port air box, install a uni filter (I bought a square and cut it out), check to see if the washer is still between the cylinder and expansion pipe (if so remove it). Keep the oil injection and maybe turn it up a tad if you really ride it hard. That's just the basic simple cheap mods

if only gas was cheaper

 

personally, i've removed the oil tank and plugged the pump and just ran mixed, you can get a finer tune with mixture. but that's me.