the full face on the crank is interesting, i'm sure ther is a good reason for this but i don't understand the thought behind this type of design, but it is not filled in behind as you can see

Hi EdwardN!!

May I ask why 51% of the weight and not 50% or even 100%?

It is hard for me to picture that in my mind! It would occur to me that the counterweight should balance the whole weight of piston, rod, wrist pin and g-clips, wouldn't it?

Isn't it like the whole weight of the piston/rod assembly is permanently attached to the crank pin, like the lead sleeve on the pin (bob), and thus we should account for 100%?

Also, if I decide to cut the crankshaft, then that means I must remove weight from the piston or rod accordingly? I imagine that is why EB Mods cuts the rods as well.

Thanks!

colt has ported a few airplane motors. maybe he could be of some help, i and i doubt he has seen a motor like that.

Sure you can ask any quetions-this is why we came here in forum to learn, share etc.
Number 51% came from many years of trials and it is our numbers, it doesn't mean everybody use the same numbers. It is target number but not always can be easy reach.
BTW, try to make 100%-you won't be able to do that, regardless how much tungsten you will put there. It is doesn't metter how much you can lightening piston assembly-you can go just to reasonble limit where parts will be strong enough to don't brake under the load while motor is running 40+ K RPM. Ones you will make them srong enough they will have some weight.
One of the reason why in air models (there is space to do it) some people try and do carb on opposite side, but we don't have that luxery. Tehere is way to make better way to do balancing-use rear induction-you can locate induction position that it will help achive best balancing with minimum unbalanced rotating mass ( way lesss then we use front induction), but again it is depend of aplication-some place is possible, some not. Please see the pics of samples.
Balancing is whole hell of controversial ideas and theories and people stick with something they find work better for them.
BTW, look the pic of sleeve-it is art of work!!!!

Hi MugenB.
That one is really old motor-that balancing on cranck was popular because on that time idea was that cuts which we have now on cranck will increase case volume, so everybody was making those cuts and some times even put sleeve over it to cover cuts. But later it was proven that web regardless the shape at rotating in our RPM is concidered as full round body, so after it was proven, everybody switched to DELTA type ( or alomost everybody ).
As far as engine-pics are really not focused, but for sure what I will do is make the cuts which going from transfer ports to booster-it will be firstTo make sure mixture passage is good to all ports, second I will do is to make chamfer on induction hole ( or you can make turbo scoop). Will make sure that booster angle is at list 45 degrees.
Try to make please more focused pics of the side of sleeve where we can see transfer ports and booster.

Thanks for taking the time to answer this kind of question.

Not many people out there are willing to share this much good info!!

You are very welcome.
It is not secret info at all-it is very well know facts in engine design world. I am not sure why people is hiding this kind of info from the community ( if they have this info), I don't see problem to help people to understand as much as possible on nitro engines.
But please understand me right-all info which I am sharing here is info which I presonaly with my firends got over the years, it doesn't mean it is mother nature laws, it just what we have learn. Some of the info is not supported by any mechanical, thermodynamical, flow etc rulls or laws, it was collected over the years and found that is the best fit. Some times we even so leasy to go and try to match some scintific development to the findings. Just found and used.

ED, i just had a guy tell me that when you reduce head clearence that it will increase power and also reduce engine temp. is this accurate. in my experence it has increased temp. go to the head clearence post and see what i'm talking about please.

ED,German,Colt
can you tell me what size degree wheel i should use on my engines, does it matter, i would think so. just not sure. Thanks

I am using this protractor http://quintgraphics.net/cart/index....2b8fdb138e119d, you can easy get from Home Depot or most hardware store. I love it because it is not 360 degrees, it is 2 X180.
It is really doesn't metter the size as long as it is handy for you to use.

What Ed posted would work just fine. And also very cheap and easy to get ahold of.

sorry but that link shows 2. is it the round one or the long one, and why wouldn't you not want one that is 360 compared to 180. why is that better for you thanks ed i know that boost port angles and induction angles are very important to know for the sleeve along with boost port passege angles and fuel port paseg angles in the cace of the motor. what too do i need to check those.