stroker450 Posted April 4, 2011 Report Posted April 4, 2011 I rebuilding a 350 alcohol cheetah cub motor. I have a few question on it, the pistons i bought Are 513M06500 Wiesco Prolites 65mm. The windows on the new pistons are alot smaller than the ones that were in it. My question is should i just take those to the machine shop to have them matched or can i buy the correct ones already cut to the correct window size. Also since the the cylinders are nikasil can i have that honed? or do i need to replate it. Quote
BigRed350x Posted April 4, 2011 Report Posted April 4, 2011 I rebuilding a 350 alcohol cheetah cub motor. I have a few question on it, the pistons i bought Are 513M06500 Wiesco Prolites 65mm. The windows on the new pistons are alot smaller than the ones that were in it. My question is should i just take those to the machine shop to have them matched or can i buy the correct ones already cut to the correct window size. Also since the the cylinders are nikasil can i have that honed? or do i need to replate it. You can port-match the piston windows if you want. Its good for MAYBE 1-2hp. But you're weakening the pistons and increasing the risk of having a broken skirt. Port matching your cases would be a better investment of your time and materials. You can hone nikasil, but it requires a diamond hone to be done correctly. Don't go too crazy with it though, you just need a light cross-hatch on the cylinders to get the new rings seated. Quote
theshee Posted April 4, 2011 Report Posted April 4, 2011 You can port-match the piston windows if you want. Its good for MAYBE 1-2hp. But you're weakening the pistons and increasing the risk of having a broken skirt. Port matching your cases would be a better investment of your time and materials. You can hone nikasil, but it requires a diamond hone to be done correctly. Don't go too crazy with it though, you just need a light cross-hatch on the cylinders to get the new rings seated. Damn Jared that good info... i remember when I got my last pistons ported i was told it was worth way more power then that... if its only 2 horse I would fuck with it and risk breaking a skirt and causing more damage then its worth... (stroker450 is Mario Jared, guy we rode with at walden that time with Dan, Katie, you and I)... Quote
stroker450 Posted April 4, 2011 Author Report Posted April 4, 2011 Thanks for the info guys!! Whats would port matching cases, sorry im new to all this? And where can i get a diamond hone?? Quote
J-Madd Posted April 4, 2011 Report Posted April 4, 2011 You don't usually have to hone nicasil at all. Also, what were the numbers on the old pistons? Are you running a stock rod length crank or + 5mm? Quote
BigRed350x Posted April 4, 2011 Report Posted April 4, 2011 Damn Jared that good info... i remember when I got my last pistons ported i was told it was worth way more power then that... if its only 2 horse I would fuck with it and risk breaking a skirt and causing more damage then its worth... (stroker450 is Mario Jared, guy we rode with at walden that time with Dan, Katie, you and I)... Ahh, good to know! He sent me a PM today. The hp number is just what I've been told by a couple different builders. I haven't ever done any dyno time to confirm/deny it though. - Jared Quote
BigRed350x Posted April 4, 2011 Report Posted April 4, 2011 Thanks for the info guys!! Whats would port matching cases, sorry im new to all this? And where can i get a diamond hone?? Mario, I'm not totally sure on the nikasil stuff. I haven't run anything with nikasil in years. I'm part of the billet crowd and our cylinders have iron sleeves. You might not need to hone at all. J-Madd says you might not need to hone. Give Kevin at Herr Jugs Racing a call and ask him, he won't steer you wrong. His number is in my signature. - Jared Quote
stroker450 Posted April 5, 2011 Author Report Posted April 5, 2011 Numbers on old piston were 513M06500 Wiesco Prolites 65mm. I bought some of the same ones. should i just throw it all back together without honing? and what compression numbers should i be at? Quote
J-Madd Posted April 5, 2011 Report Posted April 5, 2011 Yes, unless the plating is damaged, just put it back together with new pistons. What size domes are you running? You should've checked compression on the old pistons so you would have a baseline to go by. On the latest Cub I rebuilt, the new pistons and rings only brought up the PSI by about 5. The motor was ran hard all last year at the track and even had some deto while on the dyno, but I didn't change the pistons. Quote
stroker450 Posted April 6, 2011 Author Report Posted April 6, 2011 My numbers where 125psi on each one. Domes are cut by kim at K&t for alcohol. so where should i be at Quote
J-Madd Posted April 6, 2011 Report Posted April 6, 2011 So your running different domes this year....I thought you were running the same. All of my 421 Cubs have 180 - 185 PSI. I have 19.75 cc domes in one, and 19 or 20 cc domes in the others. PSI will differ based on the exhaust port height. Those 421 cubs are usually 197 *- 198*. I don' t know what the 350 Cubs usually are. I'm sure K&T will put the domes right where they need to be for ya. Quote
BigRed350x Posted April 7, 2011 Report Posted April 7, 2011 So your running different domes this year....I thought you were running the same. All of my 421 Cubs have 180 - 185 PSI. I have 19.75 cc domes in one, and 19 or 20 cc domes in the others. PSI will differ based on the exhaust port height. Those 421 cubs are usually 197 *- 198*. I don' t know what the 350 Cubs usually are. I'm sure K&T will put the domes right where they need to be for ya. The static compression will also be greatly affected by altitude. We are a lot higher than you J-Madd. 19 and 20cc domes are still pump-gas range around here. We need 17's and 18's to get up close to where you're at with 19's and 20's. LOL - Jared Quote
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