421 Cub - What pipes ?

[Pasi S.]

OK. I´m asking this for my friend.

He has un ported 421 Cub with 34PJ´s, VF3, pod´s, coolhead, stock timing plate and T6 pipes.

I don´t know the compression, but he needs to use 110 race fuel.

He likes to ride open and fast trails, hill climbing and 1/8 on asphalt just for fun.

If I remember right he has +2 swinger and 17/38 gearing.

 

What I would like to know is whitch pipes are best for him for that kind of riding?

 

I was thinking CPI´s (sb-if) and +4 timing .. but I would like to hear your opinion about this.

Also if someone can tell the power difference between T6 and CPI.

 

Thanks!

-Pasi S.

Edited November 8, 2009 by Pasi S.

[dekker]

OK. I´m asking this for my friend.

He has un ported 421 Cub with 34PJ´s, VF3, pod´s, coolhead, stock timing plate and T6 pipes.

I don´t know the compression, but he needs to use 110 race fuel.

He likes to ride open and fast trails, hill climbing and 1/8 on asphalt just for fun.

If I remember right he has +2 swinger and 17/38 gearing.

 

What I would like to know is whitch pipes are best for him for that kind of riding?

 

I was thinking CPI´s (sb-if) and +4 timing .. but I would like to hear your opinion about this.

Also if someone can tell the power difference between T6 and CPI.

 

Thanks!

-Pasi S.

\

 

 

CPI or Shearer are definately the way to go with a cub. The T6's that he is running are designed for a stock port machine. CPI's power is going to come on later and pull longer than whats currently on the bike. Keep in mind both the Cpi and the Shearer are in frame drag pipes that work best in the higher rpm range.

[rubberneck]

I ran shearer inframes on my duner 421 cub, it ran hard. CPIs are supposed to come on a bit earlier and that may be an advantage if the bike is not a strict drag bike. I have never tried the CPIs but would probably go that route if i were doing it over. Shearer pipes fit like shit and the chrome is horrible. I have a set of inframes and oof and Ill never buy another shearer pipe.

[r/atvshee]

If its not a drag bike, then I would go with a set of CPI's. I used them on my old 421 cub and they were great pipes. I never got a chance to try a set of Shearers though.

 

Also, since he's running race fuel. Bump the timing to +7.

Good luck keeping the front end down with that +2 swinger..

[potpye]

CPI inframes, if you have any doubt give Mike at CPI a call he is very sharp.