Advice on starting point jets for 421 with Keihin pwk 35s

[itsascrewdriver]

Hi there,

I'm currently building a 421 4 mil and I'm hoping someone can point me to a good starting point set of jets since I've never run a Keihin carb before.

I'm in Utah and most riding is done around 4500-5000 ft above sea level

I'll be running Keihin PWK 35mm carbs, K&N pod filters, VForce4 reeds, SLP in frame pipes, cool head with 21cc domes, and 4 degree timing advance.

 

From the What Jets are you running sticky I found a likely seeming setup posted by Handyman that's using
155 mains with 48 pilots, I was thinking of starting a little richer and doing chops to tune it in.

 

Any advice would be appreciated

 

Thanks 🙂

[dano3]

Redline serval with same mods except i run shearers and depending on temp at 1000ft above sea level I range from 148-158M and 42-48P with a CEL needle. Start rich and work your way down slowly. I followed that duncan racing jetting PDF to get pilots close when I first put it together. Also, ask your builder???? 

[itsascrewdriver]

Unfortunately I'm my builder, so asking me isn't a great option. /s
Thanks for the info on what you're running though.

[dano3]

3 hours ago, itsascrewdriver said:

Unfortunately I'm my builder, so asking me isn't a great option. /s
Thanks for the info on what you're running though.

Who is porting cylinders and cutting domes for you? Ask them