Why is it that everywhere you turn around, you hear people talking about wanting to bore their quad's cylinder "to the max" to get "more power"? What do you gain in boring a little single cylinder engine - 5, 8, 12 cc's?? That's what?, about 1/4 of a weedeater engine? Of course the end gain depends on the original displacement, too.

My '87 TB 250 engine has been bored gradually over the past 16 years to the point of 1.00mm (.040"). Using the formula in mm [ (bore X bore X stroke X 0.0031416) / 4 ] that's from 244 cc's to 251 cc's - what a HUGE gain - 7 cc's [img]i/expressions/face-icon-small-shocked.gif[/img] What about the 500 engines? - stock 498 cc's to 1.00mm (.040") = 509 cc's - another HUGE gain - 11 cc's [img]i/expressions/face-icon-small-shocked.gif[/img] [img]i/expressions/face-icon-small-shocked.gif[/img]

My 2 cents - Is it not more sensible to bore the cylinder to the next required size, saving the cylinder for several future repairs?

 

An old hot rodder's saying might answer your question.

"There is no replacement for displacement" except nitrous, turbo, supechargers,yada yada yada. LOL

Most of the guys I know don't really care about saving the machine for years and building it when it needs it. They just want the instant gratification that comes from building a machine that beats everthing on the hill this week.
They live by the addage of "Run what ya brung and hope ya brung enough". And it is also good for the economy.
LOL


Rider

 

More conservative people like myself only bore to what is necessary for reliabilty.Excessive boring I feel is a waste. If you wanted more cc's get a larger engine.Or quad in some instances.

 

Kind of on topic. I have a 330 Trail Boss. I've piped it, K&N and vented air box, jetted it and installed a better primary spring. What to do next?

Well, RCR sells the 414 kit. It consists of a new sleeve and American piston for this Fuji engine - 414cc. He will also polish the ports. He'll do this to the Trail Boss 325 - still looking at the 330 to verify the feasibility.

Is it worth it? I think so. It will give it more lower end torque and off-the-line-speed. I like the quad and would do it all over again. To each his/her own. Remember, the refrigerator is never full. Most everything of this nature (quads) asks for more. I like to give to it.

Lukester