hello,
maybe pat or someone who's done the 904 can help me out with my questions here.
i'm hoping someone can give me some feedback. my motor recently took a crap on me at 50,000 miles. i haven't taken it apart yet but i think it might be a bent valve or something came loose in the head. it just started making a bunch of clackity clack and that was it. fortunately i have someone who "rented" me a temporary motor while i take care of my problem. so i'm running that for now. i've been wanting to do the 904 big bore for awhile along with porting the head, and possibly the b/c stage I street cam, AND fcr or cr's.
my question is about the difference in bonneville, thruxton, and america motors. my understanding is the 270 firing angle makes for a smoother acceleration while the 360 provides more torque and power. if i'm after torque and power then is there any advantage to having an america motor?
next question is about compression? i don't really know why more compression is better but i know it is, if someone can explain. and i see that the thruxton comes 10:2:1 while america and bonneville is 9:2:1. what kind of compression does the 904 provide?
which leads me to my next question. i often go on long rides of 1,000+ miles and i would say i ride my bike pretty hard (80-95mph.) if the 904 adds more compression than originally intended for the motor, is something more likely to break under the stress? especially with more miles?
i've been wanting to upgrade the performance of my bike for some time from the setup i've been running (epco pipes, no snorkel, thrux needles) and i'm finally approaching the time to do it. but i was checking out the specs of the thruxton and i see they're almost at what the 904 does. there's a couple thruxton motors for sale now so it got me wondering. i plan on keeping this bike forever and don't want to mess with performance upgrades in the future. may i also add i would be doing this all myself and have never taken an engine apart before. but i do feel that i am pretty mechanically inclined.
what do you think? what should i do?
unbiased opinion please
