interesting post,..
i recently built a 1610cc 5mm over bore with 6.25 welded falicon and stock length carrillos with .125 spacer.
pros-cons,... my experiances with busa's even with update starter drive gears,. etc and very good battery can be hard start if not well tuned. add any combination of bigger motor higher comp, its gonna have hard start and especially hot start problems,.. no offense to those who have no problems,.. in my shop i get one or two a week to diagnose and try and repair!
bigger is bigger period! the main difference is how reliable and user friendly it is!
as to reliable,.. that is in fact directly related to RPM/HP i've heard from reliable sources that stock rods are good to 500 hp,.. in my years of engine building never one!!!
any stroker/bore will raise the compression ratio and or produce harder starts and better gas requirements!
if you talk to very experianced racers builders they'll all rule against shorter rods,.. then stock as it decreases engine power and efficency, and the increased piston speed and higher rod angle greatly increases wear and tear!
All of the "Reputable experienced builders reccommend stock length rods and spacers,..
problem with even an 1/8 inch spacer is the upper motor mounts dont fit gatta drill out or jury rigg it!, also 6.25 mm stroker is considered the max to use the stock length chain other wise different chaing gear set up,.. which id do anyway!
id not waste my time building a bigger motor with hahaha stock cams and head,.. why bother?
Personally from my own builds id build a stock engine size with GREAT HEADS and CAMS,.. degreed,. with full system exhaust and velocity stacks,... a few other small things,.. its totally relable,. and mostly easy to build up and works the the best stock bike on the road!
whatever you decide good luck,... may the HP be with you! robert
I'm about to pull the trigger on a weld-up stroker crank (billet is too much $$$ for my poor ass).
Initially my plan was an 8mm or so, with 2.5mm shorter rods and appropriate spacer. Now I'm thinking of just doing the more common 5mm to end up with what should be a more reliable 1507.
What are everyone's thoughts? Is it worth considering the 8mm? Will it be that much harder on everything? How significant would the difference in power be between 5mm and 8mm?
I think I'm down to either 5mm, or 8mm... I'm not keen on the idea of a 6.25mm, since it would require a thicker spacer plate with stock length rods, and I don't want to run a shorter connecting rod if I don'