I already have my order in on the 105.5 big bore with 14:1 which will bring me to 726cc. Also plan on adding a race head (larger valves, porting, springs and cams). I am trying to decide if the stroker crank is something I should consider while I have the motor apart. It would bring me to a total of 800cc. Price along with performance are some of the factors. Any suggestions on which direction to go?

 

have you seen one of the 105 bore machines run yet? the big strokers are interesting and probably have more pure potentual but so far the 720 are pretty close. could be a monster machine when all done.

 

do you want topend power or low/mid torque? how many RPMs do you want to turn? the extra long stroke will limit RPMs.

I know of a stock bore, stock stroke DS, stock valves, on alky making 80RWHP. It can turn over 12,000RPM.

 

Yep. I agree with Scooby and Sandman. Dont look at biggest CC and longest stroke as the goal. If you can get rmp and torque in a shorter and more effecient stroke, thats the way to go for the DS.[img]i/expressions/face-icon-small-tongue.gif[/img]

 

So who or what type of ridding would a big bore long stroke engine be targeted at?

 

At this time my 720 is faster than the 770 but the big boy is more fun to ride!!!!!!!!!!!!!!!!!!!!!!!!

 

Wy make 80hp at 12000rpm when you can make it at 7500rpm? I have learned from my little high rpm 200x that big rpm requires lots of maintenance.

 

My 733 is stroked 5mm and it has no trouble turning rpm! In fact i have to be carfull and keep an eye on the tach!
I turn it to about 9500 with no problems but im leary to turn it higher do to piston speed. Theres no real point in turning it higher than that because it made peak power at 9000, thats what gears are for!

 

Since you have both, what makes the 770 more fun to ride? Your 720 is faster because it can rev faster?

 

Excellent point.