Quote:
Originally Posted by fan4chevy
Sycarms, good explanation. I can fully understand that weaker metals can overheat or prematurely fail.
I think I am likely to go with a 60-61mm kit. I hated to have to take it to a machinest locally who is the only one in town so is about $50. So I was considering the bolt in 60mm or the bolt in NCY 61mm.
Xlint89 I have 13/40 internal gears too. How is the performance after all the parts upgrade with those gears?
Xlint89, you did not feel the need to go with the 30mm carb set with big bore and stroke?
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I believe it was Jmansrocket who stated not to go with the 60-61mm drop in.Now I'll reinforce that statement today. Do not go with a drop in any larger than 58.5mm. The 58.5 is nothing but a bored out 57.4 stock cylinder. Any larger than 58.5 the case needs to be bored out to fit the larger OD diameter cylinder sleeve. I know a dealer who once sold the 61mm drop in cylinders. Everyone he had sold failed. The reason is simple. A stock cylinder can be bored safely to 58.5mm any more and the sleeve is too thin. To achieve a 61mm or larger cylinder the sleeve needs to be a larger diameter OD in order to have enough metal to handle the constant forces of piston to wall. What the Chinese have done is to take a 61mm cylinder and to make it a drop in machine material off the bottom of sleeve that protrudes the cylinder. This leave too thin of material at the critical point where the piston transitions from down to up. It is this point that the piston creates sidewall pressure against the bottom of the sleeve. It will eventually crack the sleeve and most times at high rpm's forcing the piston up sideways destroying crank, cylinder, case and head. A big bore kit alone will not give you any more power. Your power 90% will be made from the head and camshaft. A Quality performance head properly ported along with a performance camshaft will give you the most bang for your buck. Only after your head and cam have been upgraded will a big bore kit make any difference. The good quality performance parts for these buggies cost a fraction of what it would cost for any of the popular Jap brands. If your on a budget than save until you have the funds to do it correctly otherwise you will have wasted money on a short lived project leaving you disappointed and with no ride to enjoy. There are only 2 ways to do something, the correct way or the cheap way.