whats the samllest dome/most compression

[snowmanzz13]

some where i read that when you run smaller sized domes, such as 18's, or smaller, you run a risk of really hurting the crank, it makes sense but i don't want to be the one who does this expierment. SO whats the smallest domes that would be safe to run on a stock, un welded crank? and also whats the smallest dome you run period?

[theshee]

smallest ones Ive ever seen are 16s. I run 20s in my bikes.

[snowmanzz13]

so i really don't need to worry about my crank on a smaller dome size like a 17 or a 16 then? i've been thinking and i really want power so i'm thinking of actually going beyond 18's

[chevy7398]

youll be needen some high octane high dollar fuel to run that high of compression, i run 108 octane and its 5.25 a gallon and if your going that low you better be runnin higher than 108

[Snopczynski]

I run 50/50 race gas on 19cc on a stock unwelded crank.

[snowmanzz13]

i'm def going to do a compression check and of course ask on here what would be recomended octane for that compression and i know where to get vp 112 and 115 i think is what it is but i guess i'll be loking for like 16's

[zach45]

i have seen 15-14 on ebay...

[shee rips]

be prepared to lose a bunch of rpm on top with that high of compression

also i would think the rings would wear out significantly quicker, im not sure about that though.

[400rednEX]

my crank started separating running a ported 145psi 355 so i would check it often or better yet, weld the crank.

[jbooker82]

My compression is 185-190 on my blaster piston 400cc motor. I just run Sunoco Standard 110.

[RoostRocket]

my crank started to seperate running 18cc domes before i had it welded. but my buddy had 19cc domes on a stock crank no problems. so it really depends on what condition your bike is in. im sure the 1cc diff. wasnt what caused my crank to seperate but rather my bike had been abused far more than my buddys.

[rocketboy]

be prepared to lose a bunch of rpm on top with that high of compression

also i would think the rings would wear out significantly quicker, im not sure about that though.

 

 

yep youll get lots of lowend on anything below 18cc ...but theres a hefty price to pay ...like lose probably 1500 rpms and thats most likely where your bike will make most of its hp and torque.you will also murder your crank and rod bearings and rings will wear faster at over 180lbs of static compression .if your stock unwelded crank is thinking about seperating it will do so under those extreme pressures .id run either 19cc or maybe 18cc on a 350 ,your porting plays a big part in this too