i run the new hpd race pipe on scrambler 400 2x4,
i only get 7000 rpm at full shift out with the proper aggressive clutch kit and pwk 39 mm carb and hpd claim to get the pipe at 7350 to 7550 at peak mods,what are you guys rev this pipe to,thanks.

 

whats your gear ratio?

 

[img]i/expressions/face-icon-small-happy.gif[/img] Hey scrablered, you did not mention whether or not your cylinder has been ported. If you are running a stock cylinder, then about 7000 is all it will turn to work correctly. A trail ported cylinder will go about 7200, and the race porting will go about 7400-7500. Gear ratio on a variable transmission has nothing to do with the rpm of the engine. That is all determined by the clutches and the motor output. As your clutch starts working, it loads the motor. Naturally a ported motor will keep the rpms up where it should be while it shifts out. If your motor has been ported, then you might have to change your primary spring. I run the blue primary with 10A weights. When swapping to the race setup, fine tuning becomes more crtical on these machines. Good luck and dont give up.Bubba

 

Like Bubba said, the tuning is in the clutch. Give Darrell or Mike a call, they'll help dial you in.

Ken

 

the motor is trail ported with hpd heads,run 13-30 gearing with the sprockets,42-36 hpd helix,hpd aggressive clutch kit...
is the blue hpd primary spring you're running?
what the 10a weights for real?thanks.

 

i'm only to find out where i can peak my clutch tuning here,with a new
hpd belt with trail ported motor it turn 7200-7300 easily so i think
it alright...
i run the hpd clutch kit wich seem not perfectly dialed-in right now,
i really suggest the 13-30 gearing to get most of the rear wheel hp,with a litle more helix to start to you got a cool top end power...
the biggest problem on those 380 2 stroke is when full modded the engine radiator capacities isn't enough to get cool-consistent performances.

 

Not bashing here....but watch the primary clutch for grooving when using the HPD kevlar belt. Just picked up a new clutch and gonna try the 700 belt.

Ken

 

for all of you running on race gas like 105,108 octane heads,do you proceed normally to pre-mix the proper oil ratio?
i run klotz r-50 oil with ER metal conditioner only,thinking to put back the 14.1 head...

 

I run 40:1 pre-mix with 110 octane, and plain old Polaris blue non-synthetic.

Ken

 

o k,i known what you're talking about,the klotz oil is for use in hight rpm engines...