I have always thought big bore kits made their power from the extra CC's they deliver over stock. The extra CC's do help, no doubt about it. I believe the power comes from the internal modifications. Like valves, valve springs, cams, etc. Now my question is this.

If I bought a big bore kit and did everything to my quad to take advantage of the extra power would I notice a big power difference if I don't install the larger pistons. Everything but the extra CC's. I think I would attain about 85% of the power without the extra CC's but I would gain the reliability of a stock bore motor. Now I have another question.

Would the kit work properly without the extra CC's the kit was designed for? I like the idea of mad power but I don't like the idea of new pistons, machining the cylinders, etc.

Thanks for your input.

 

The oversized pistons have deeper valve pockets so that they will have enough valve clearance to work with the bigger cam. If you put a four stroke tech cam in a V-Force with stock pistons, then the pistons get to eat the valves for lunch. So if you are going to "do everything but the pistons" you would need to do it with a different brand of camshaft, such as webcam or hotcam.

 

Go big or stay home[img]i/expressions/face-icon-small-happy.gif[/img] Just kidding!
I think if you are going to do all that internal why not finish the job right. The more CC's equal the HP you make! I am no where near capable of being right, just my opinion!

 

Have to agree with wildwill.... you are gonna be spending loads of moolah on this so why not do it all? you say you might gain as much as 85% as what you woulld gain by doing the larger bore and I think thats a bit liberal -- Make it big and throaty and you wont be dissapointed.

 

I think the only reason big bore kits sell is because of the extra CC's they deliver, the internal mods make all the power not the extra CC's. The CC's sell the kit that is all. Of course they help the power delivery downlow but thats about it.


I'm wondering if I get the entire kit beside the pistons and sleaves and different cams that if it will still work as intended but not with as much power. Of course I would like the big bore but reliability is much more important to me.

 

i like the bore on the machines that i have done

 

There's only 1 problem with that theory. With the larger cams thatyou would be getting with the FST kit(longer duration, more lift, and overlap) you need higher compression for those cams to work properly. If you don't raise compression you WILL lose power. Even Mickey said that his cams are not for stock engines. You may be able to get away with installing his high compression pistons for the stock bore.

 

I would use the cams meant for a stock bore, web or hot cams.

 

Mickey has high compression pistons in the stock size (he said that once).

-You don't need to have a big bore kit to use his cams as long as you raise the comp (and have clearance, obviously).
-You will gain upper RPM horses with his cam even if you don't raise the comp. You will loose lower rpm power if you don't raise the compression while using his cams.
-Although any cam is better than stock (even stock retarded), you really should have professionals port the heads if you are expecting to get more umph.

If I was gonna mod mine, I would probably do everything except the bigger bore.

I like to ride mine a bit easier. It has enough power with the Dyna CDI right now. I don't need to mess.