They is no substitute for cubic inches, lots of torque! There is a lot of other things that need to be changed to make that combo work. I don't have the funds to try it but the imagination runs wild![img]i/expressions/face-icon-small-happy.gif[/img]

 

You don't see many of the super big bore 727 and 770 because in my opinion with a proper engine build you can accomplish the same gains with a 660 or a 672. The ability to rev is what wins races. I think people get caught up in this huge displacement war when it comes to the raptor motor ,not knowing it's true inner workings. The raptor get's 90% of it gains through extensive port work and the valve angles and the other 10% is your pipe, cam, carbs, etc. etc. You figure out to make those two work together and you can take a stock bore machine and easily out run 770.

Another aspect of the game that people seem to neglect when building a quote unqote drag racing quad is their gearing and suspension set up. I've seen guys and have been one myself where you get your @ss waxed on the drag strip due to improper gearing and suspension. You can have 10 more HP than the next guy and with improper he will leave you behind wanting everytime.

 

from what i have seen with a raptor i would want a big motor. to ME they don't seem to rev good. so get all you can get out of them on the bottom end, (big bore stroker)

 

I agree 100% with velocityraptor, thats why I am only working with a standard bore 660. I want to see for myself how much in performance gains (port work, cam, ignition modifications) I can get without going big bore. Also a standard bore raptor would be a lot more reliable in my opinion.
I have seen standard bore 350cc Banshees produce 65 horsepower with the proper portwork and pipe all this can happen. I am not saying that you also can build 65 HP out of a stock raptor, 50 to 55 HP is more realistic.

 

There are stock bore Banshees putting out around 90hp but you are talking about total drag monsters running on alky or meth, some of them will run in the low 4s in 300ft drags.

 

Going "big bore" wont hurt your revs will it? just stroking it increases piston speed therefore limiting your revs. Be careful who you get to do your porting though, I think they have one port job for their race bikes, and one job for us "civillans"(if your not a civillan your competition and really dont want em to port it [img]i/expressions/face-icon-small-happy.gif[/img]), wouldnt you? Not that anyone on this forum would do it to you [img]i/expressions/face-icon-small-wink.gif[/img] . Pretty much your just screwed unless you happen to be friends with a shop owner or racer, or learn to do it yourself. Another part of that is they are probable scared they will over do it and mess up your stuff (atleast thats what they tell themselves [img]i/expressions/face-icon-small-happy.gif[/img])

 

Why is it that a big bore won't rev as well as a standard bore? My guess would be piston weight, right? So if a larger bore piston was made to the same weight, or close, what would the limiting factor be then?

 

When ever you go to a larger bore size you must increase the air/fuel delivery going into the combustion chamber. If you do not you will loose revs and it will feel like a stock 660R at top end, but it will feel like a 770 at bottom through mid range. Higher rpm can be gained by increased cam lift and duration, a lot of port and bowl work on the cylinder head and a good exhaust to get the gases out of the cylinder head, also a good air filter (K&N) Yes lighter rotating components will help as well.