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Engine Upgrade Options, Opinions??
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Posted by: YFZRob

As some of you already know, I have bought a mint condition, all stock '88 250R. I would like to keep it this way other than some added HP. I ride a YFZ450 normally, and I will use this for any competition riding. The R will be mainly for trail riding, but I want YFZ power so it's not boring to ride.

I have been looking into the CT 310 kit, which is a pretty good deal for $1450. It comes with a CT custom ported cylinder (to your desired powerband), piston, gaskets, PWK38 A/S carb, v-force reeds, midrange pipe, ect ect. With this kit, I can simply swap top ends before the original jug needs its first rebuild. This way I can simply swap the stock top end back on the motor if I ever want to return it to stock.

Other than this CT kit, does anyone else have other top end engine kits to be suggested? Does anyone know if something like this CT 310 kit would give me the power of my bolt-on YFZ? CT racing claims it will get "close" to it, but not the same or more. I am NOT willing to go to a kit that will require case machining. Any suggestions would be greatly appreciated!

Posted by: baker250r

ive heard bad things about the CT packages. I dont mean to start a big arguement, but i guess thats what ive heard. from eveybody ive talked to that has their kits. I would keep the stock cylinder and get a port job on that, or else buy a cylinder off ebay and port that, and keep ur cylinder in stock porting and bore and everything. then run a pipe and air filter, and u should have a nice quad. I am a duncan man myself, so I would go with a duncan cylinder kit. but LRD, ESR, and Baldwin all are good companies.

Posted by: Knips178

definately go ESR. Call eddie sanders and tell him what your looking for and he'll make some recommendations. They have 330cc bolt on kits available that should give you some very good power.

http://www.esr250.com/

the phone number is 559-625-3157

Posted by: YFZRob

Thanks for the replies! I contacted Darren at ESR this morning. He suggested their complete 310cc kit which comes with the following: 310cc ESR cylinder, ESR head, ESR pipe and silencer, CR reed block w/ intake boot, piston, rings, wrist pin, gaskets, and Keihin PWK38A/S carb. Total cost is around $1800....still $350 more than CT, but it seems that ESR has the better reputation with the 250R than CT. This would be EXACTLY what I am looking for. YFZ450 power, reliability, and a complete top end swap, literally. I can take the entire stock top-end and set it aside.

Posted by: Knips178

ESR is worth it from everything I've read. I don't personally own an ESR cylinder, but I've ridden with and against people with them and they fly. did you ask specifically if it would feel like your yfz450? cause even with the lowend port job, it will still feel different. i don't know if you own any 2 stroke quads, but it's quite a bit different from your yfz.

Posted by: YFZRob

I didn't get into it specifically, but I know of the drastic difference in the powerbands. I have never owned a 250R, but have ridden quite a few. I personally find a 2 stroke more exciting to ride, so if I can get similar power numbers from the 250R, I'll have more fun riding it. My main goal is to get the two to be similar in a drag race. I really enjoy drag racing, and there's nothing sweeter than the sound of a piped and ported 2 stroke ringing through the gears at full throttle. The main objective of the 250R is to use it for trail riding and some "just for fun" drag racing. I will stick to the YFZ for competitive racing.

Posted by: Knips178

then you should go with ESR's mid port job, i think it's the trx7 port job, but not sure on that number. would give you a good medium between drag racing topend and woods riding lowend.

Posted by: beak7707

I am also a huge ESR fan, thats what I would recommend.

Posted by: ZillaRider02

I don't run an ESR cylinder, but can vouch for their TRX-5 Center Mount Pipe, 39 PWK Carb, Cool Head, and Filter Kit. Top notch stuff. Made a HUGE difference on my bike (265cc stock cylinder). BTW, they have super fast shipping and excellent customer service.