Cylindrée maxi (in english)

Voici, à ma connaissance, l'histoire récente de la plus grosse puissance tirée du mythique 223 cc que nous connaissons tous. Cette "recette" vient de mon contact américain qui bricole ces moteurs comme Maïté les lapins de garenne. :-D

"I just finished a Performance hopup project for my father ! in law. He started riding at age 57. I told him to get a serow for obvious reasons. That coupled with the fact that my wife and I have five boys, and we are heavy into dualsport and dirt bike riding. Now after two years my father in law wants more power, but doesn't want to deal with more weight. Hence the project. Hers are the details.

Wiseco 71mm 10.25 to 1 piston custom made 2.5mm offset crank pin made by my father in law
using A2 metal heat treated to 62 rockwell. Making the effective stroke a 5mm increase.
Current bore and stroke is 71x63 total cc is now 249.4
2.5mm spacer for the cylinder to reset piston deck height.
Current calculated compression ratio is 12.3 to 1 ajusted by splitting the three ply head gasket

Had to do some minor die grinding to the cases to accomadate the extra crank throw. Also had to remove some material off of a corner of the counter balancer to clear the piston at bottom dead center

Removed aprox 1 pound from the flywheel

Modified a SUSUKI DRZ400 S model stock exhaust for unrestricted exhaust flow while keeping the bike relatively quiet ported the restricted exhaust port.

Did a minor cleaning up of the intake port installed a 6005 bearing on the sprocket side of the cam to get rid of the aluminum bearing which is prone to gauling if there is the slightest oil starvation to the head got rid of the linkage shifter and went direct while adding a inch of space between the foot peg and the shift lever total 7 inches added one link to the chain to increase wheel base dropped to a 14 tooth counter shaft sprocket the RESULT ... Amazing!

Keeping in mind that it is been hoovering between 10 and 20 degrees the last few days and the roads are a little sketchy.

Roll on in first and second gear produces wheelies.
Power shift to third pops the front end right back up in your face.
Running in sixth gear, reducing speed to 20mph. then twisting throttle produces a acceleration instead of falling on its face.
Oh ... I am running stock jetting, however I have raised the needle 75 thousanths which is standard proceedure for these bikes anyway.

It was a fun project that was cheap to do only because of my father in laws capabilites and access to the high tech equipment.

I personaly own a DRZ400 with a aftermarket pipe, so now you know where the exhaust came from."