This is just a curious question. Both these modifications up the displacement in different ways.

What are the differences between the two, in terms of : reliability? powerbands? cost? and pros/cons of both.

You see alot more over-boring than stroking. Why is this?

And if you are feeling up to it, which do you prefer and why?

 

Overbore only requires removing the cylinder and leaving the block in tact and in the ATV. That alone would not take much effort at all.

A STROKER lengthens the stroke (movement up and down of the piston in the cylinder) and requires removing and replacing (or having modified) the crank, Rod and/or piston.

An overbore WITH a stroker kit is the best way to add reasonable displacement.

Maybe someone else can post opinion on which does better for power and in what power band.

 

Well, I know that. I'm looking for specifics such as those listed in my original post.

 

my understanding is you gain alot more power over all from the bigger bore. stoking improves the torque aspect, as opposed to making have more horse power. go big bore

 

This is what the guy at Wiseco told me when I bought my crank. A stroker will be better for low end tourqe. Overbore will get you the top end speed. Reason he gave was that he piston has a longer stroke, which in turn lenghtens time it takes to cycle between intake and exhaust. With the overbore, you are keeping the stroke to a minimum, but still trying to increase your intake and exhaust.

He used some gee whizz garble that I am not even going to try to explain, but he gets paid the big bucks and it sounded good. He said the biggest problems that people make when doing either (or both) upgrades is spark and air. He said the first thing you need to do is get more air in and out. Stock air filters will not get all the power that your upgrade is capable of. Once you get the air in and out, make sure the fuel air mix on the carb is set right. Lastly, he said usually a decent spark plug will do, but in some cases a bigger coil is needed.

I have a winter project that will take a 400ex to a 440 with a 12:5:1 Stroke and a ported head. Probably run dual exhaust and move the battery under the seat into an aluminum airbox. I have most of the stuff, just need to get a real nice coil.