dynamic crankshaft balancing

got the motor together last night. the crank went in easy. the clutch shaft was a problem. one of the bearings come out of the motor and stayed on the clutch shaft when i disassembled it. so getting that bearing back in the crank case was a pain. now i gotta get the motor swaped out on my bike. i have a shift kit on it so its going to take alittle longer. hopefully i can find the time to do it this weekend.
 
Hi foureasy. I have several motors that shake themselves to death. Do I sent the crank to you for the treatment? Also, do you have to split the crank?
 
Can you do the RAW motor crank as well? I am very interested in your current mods to the engine as well! I am planning a build up and would be pleased with 6hp if that's doable without killing reliability. I actually am VERY skilled at porting 4 cycle engines (I actually used to build Indy 500 Race engines for Nissan, as well as MANY other forms of racing, I literally have 1000's of porting hours under my belt), but have never attempted a 2 stroke. Any tips? I know I will need to raise and slightly widen the exhaust port, but I am not too sure what to do with the transfers and such other than just clean them up...

P.S. What carb and exhaust are you using?

Thanks a TON!! I am new to this bike stuff but its really FUN! I am hoping to get 50MPH with a shift kit and really good acceleration and off road climbing power!dnut

Thanks for the help!
 
any crank.
you have to put a degree wheel on to properly time and port a motor.
im using a hand made pipe and a 24mm flatslide mikuni
 
OK, thanks. I can do that, I always wondered how they got the timing. It sounds like you do it similar to degreeing in a camshaft?? Do you have any tips for a novice to get it running good? How about a quick and dirty on the proper timing for something like I am trying to do?

Thanks!!!
 
Hey Whiplash,
(you givin up on the lectrics? ) Grahm bell gives an excelent tutorial on the math formulas for small piston port engines. Lots of working examples. Nothing on crank ballanceing though. But every thing else is in there. Google will get you a bunch of places for a free download.

Has any one found a better rod for rebuilding these with? or better said a good big end bearing? I wll research for a yz60 or like that con rod. I have machine capability so resizing for a different crank pin is not a huge problem.

Just fishin for info.
T
http://www.kreidler.nl/artikelen/performance-tuning-graham-bell/performance-tuning-graham-bell.pdf
 
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114 intake
get a moped expansion chamber and make it fit without making it any shorter.
buy a real dellorto 16/16 sha carburetor.

@thud
i havent had any problems with any of the short rods, but i do have some better bearings for both ends. $15 for the big end and $10 for the small
 
So you shimmed that last jug at 6.75mm or did you change it?
Also are the replacement bearings bushings at the piston side?
 
I can't stand it I have a collection of China motors to play with. I am going to do a hybrid. This just sounds like a fun project!
 
Hey thanks! So these numbers are opening right? So I would look for the port to just barely open and then that is the timing right? Where do I get the bearings and is there any machining involved? Thanks!!!

I am anxious to try this!

I actually considered building my own expansion chamber, and build it with two cones and a straight section in the belly, any idea where would I find the math to figure out the profile? I was just going to try and copy an existing design to get close and then play with it till I got it right, but if you know a good starting point for these little motors I would greatly appreciate it!!

xct2
 
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