Can anyone tell me which kit I should get? I have all the parts he offers but I think the 502 will win because it has an aluminum billet crank with a +6 stroke and a +2 bore. Sparks is a +4 stroke and a +2 bore. Any details will help.

 

this is on a yfz i assume?

 

yes on a yfz

 

who makes the 502 kit, look at my pics their is a RIS/Mad Racing 505yfz. it hauls ***, and it lost to a ESR 480R. Look at it this way bro, and im not kidding, curtis sparks makes some of the best damn engines on the planet. He puts so little into the 490, and the power gains are tremendous. You should be around 60hp with those kits. Stroking that 450 is going to make the power come up on the top end strong and hard, you might not like that unless your plan on drag racing your 450. i know you can get 62hp on a well built 480. you can get it up to 75hp on a 495kit running alky/nos. I would stay away from the bores over 500cc, look into a well built 480 to make the same power. One major disadvantage, and this is a big one. Any motor work done by Sparks (ie. complete engine build, or even a port and polish) The waiting time to get his hands on your motor is 1 1/2 to 2 years. So if you can wait that long for a sparks build, take a number, and get in line my friend. Oh let me clarify this also, 1 1/2 wait doesnt mean you pay for it and when the time come for your bike to be worked on you send him your motor...no. You send you motor, pay for and get it back in almost 2 years. so you'll be 2 years without a motor in your yfz...lol... good luck. you might want to look into Kenz Cycle Tech

 

the bore is to a 460 and then i stroke it to a 502. Sparks is doing the same except stroking it to a 490

 

Never heard of sparks have strokers for 490s ?? Dave (CPC) had a 495 stroker at Glamis but blew up so couldnt compete at FSW, he had a 460 at Sand Mtn, NV racing the ESR 480 (new bike was stroker) and kept up with him on couple runs. Your CC level doesnt mean you will have a butt load of power, I know some stock bore bikes running with 470s and 480s. And stroking will give you more torque, but not worth it from some peoples mind. Go to YFZtech.com and ask some questions.

 

i have all of the stuff sparks offers. he did my porting cams and all of the rest of my motor work. max power is just putting the longer crank. and the crank is billet aluminum. and sparks cant do anything else to my bike except bore and stroke. i have all of his other stuff and his little tricks. right now it is a 450.