Crankshaft balancing ? help me..

[belongtomes3]

i'm building a perform street engine 1 cylinder bore x stroke 58 x 57.9 (the original bore is 52.5)

bigger piston makes it unbalance in horizontal direction ( A <-> B in the example picture )

and i figure it out that if i balance in A-B direction, the crankshaft will unbalance in vertical direction ( C-D )

the question is: crankshaft balance in A-B or C-D is better for high RPM( about 10000~11000 RPM ), drag racing ???

and which carbs is better for my engine , PWK 28mm or PWK 33mm
58x57.9 , intake valve 30mm , ex valve 26mm , running at 11000RPM ?

 

[Blaaster]

In my experience it seems best to have an over square motor for higher revs.

In relation to the carby, what size is the intake port where the carby attaches?

 

[Larry's Shee]

How much more does the new piston weigh than the old?

Darn near square bore:stroke now.

Only place I know of is Falicon Crankshafts,
Single plain brg $255, single pressed crank $337

Have you ran this new combo?

 

[belongtomes3]

In my experience it seems best to have an over square motor for higher revs.

In relation to the carby, what size is the intake port where the carby attaches?

my english isn't good, please tell me what does it mean " over square motor " ?

intake port for carbs can be modified so i want to know what carb is better for my engine and i will make the intake port follow the carb

How much more does the new piston weigh than the old?

Darn near square bore:stroke now.

Only place I know of is Falicon Crankshafts,
Single plain brg $255, single pressed crank $337

Have you ran this new combo?

i haven't measured the weight of piston , but i think new piston = ~1.5 old piston

what do you mean square bore:stroke , 58 x 57.9(~58) is it square ??

 

[Blaaster]

Square is bore and stroke the same, over square is bore bigger.

No point in fitting a carby that is larger than the throat size of the inlet tract.

 

[Larry's Shee]

What is this engine in? Bike or scooter?
What make is this engine? Honda, Pollini, etc. ?
Have you had this running and it shakes?
Have others been getting these high engine speeds?
Did you put in a different camshaft to help reach these speeds?

 

[belongtomes3]

Square is bore and stroke the same, over square is bore bigger.

No point in fitting a carby that is larger than the throat size of the inlet tract.

you mean carbs size often smaller than inlet tract, my intake valve is 30mm so maybe i will make my inlet tract 30mm and use pwk 28mm , is it ok

What is this engine in? Bike or scooter?
What make is this engine? Honda, Pollini, etc. ?
Have you had this running and it shakes?
Have others been getting these high engine speeds?
Did you put in a different camshaft to help reach these speeds?

it's honda engine , and often shake at ~3000rpm ,

 

[Awk08]

you mean carbs size often smaller than inlet tract, my intake valve is 30mm so maybe i will make my inlet tract 30mm and use pwk 28mm , is it ok
it's honda engine , and often shake at ~3000rpm ,

these pwk's you mention are airscrew type carbs designed for 2 strokes.

i'd be looking for a fuel screw type 4 stroke carb such as the keihin PE, CR, CVK, or FCR series designed for 4 strokes.

read......

2-stroke carb on a 4-stroke - Intake - Jetting / Fuel Injection - ThumperTalk

Quote from above link:
This is a nightmare project! Jetting is plenty of hard work when you have a carb designed for the engine type! Working on one designed for something different you need to be smarter than those you are asking as they are smart enough to not put a 2 stroke carb on a 4 stroke so knowbody has the answer to your question "


also:

https://groups.google.com/forum/#!topic/rec.motorcycles.tech/CZiqp-23W5g