38mm Keihin Air Striker on KX500

[Enginerd]

Hey gents,

I was thinking about swapping the factory 39mm PWK on my 95 KX5 for a new 38mm Quad-Vent Air Striker.  Do you think the 1mm smaller diameter will have horrible effects on the KX5's power characteristics?  The 38mm carb could be bored to a 39mm or 40mm to make sure that the same I.D as the factory carb is maintained.

Thoughts?
Warnings?
Stern admonishments?   

Thanks for your input!

[don46]

I have used the 38 air striker on several bikes, I bored mine to 40.5 mm. I like the airstriker because it is much shorter and moves the slide closer to the piston, great throttle response. You will have to build a neck on the back of the carb as it is probably 1/2 to 3/4" shorter.

What is your reasoning for going to the 38mm? I've been using the Lectron one one of my bikes, but they seem to be dependant on what you have in your motor as to how well they work.

[Enginerd]

I have used the 38 air striker on several bikes, I bored mine to 40.5 mm. I like the airstriker because it is much shorter and moves the slide closer to the piston, great throttle response. You will have to build a neck on the back of the carb as it is probably 1/2 to 3/4" shorter.

What is your reasoning for going to the 38mm? I've been using the Lectron one one of my bikes, but they seem to be dependant on what you have in your motor as to how well they work.

Don, thanks for the reply. My reason for considering the Airstriker swap is just as you stated. Better throttle response. My motor is stock except for a KIPS bolt, a thin head gasket, and an FMF Desert pipe with Power Core silencer. Bike runs great, and the FMF Desert really helped the top-end!  I thought I could get better response and get the quad vent setup at the same time.

I've also considered boring the Airstriker carb, and maybe having the horizontal divider plate added as well. Maybe something like this: http://www.rb-designs.com/bore-plate-carbs.htm

What do you think?

[dave916]

There are two differant lenghts of the 38mm Keihin Air Striker pwk 

[don46]

I have used the 38 air striker on several bikes, I bored mine to 40.5 mm. I like the airstriker because it is much shorter and moves the slide closer to the piston, great throttle response. You will have to build a neck on the back of the carb as it is probably 1/2 to 3/4" shorter.

What is your reasoning for going to the 38mm? I've been using the Lectron one one of my bikes, but they seem to be dependant on what you have in your motor as to how well they work.

Don, thanks for the reply. My reason for considering the Airstriker swap is just as you stated. Better throttle response. My motor is stock except for a KIPS bolt, a thin head gasket, and an FMF Desert pipe with Power Core silencer. Bike runs great, and the FMF Desert really helped the top-end!  I thought I could get better response and get the quad vent setup at the same time.

I've also considered boring the Airstriker carb, and maybe having the horizontal divider plate added as well. Maybe something like this: http://www.rb-designs.com/bore-plate-carbs.htm

There is a company called starting line products, they make performance product for snowmobiles primarily, but, they had the divider plate setup you are talking about for a 39mm carb, in fact it is 2 plates and did work well. they had these long before companies like power now and others. theirs was installed on the reed side of the car where as some others are on both sides or on the inlet. there is something to turbulance and performance at the carb, on one of my old sleds it had mikuni round slides, I bought a product that went in the bottom of the slide to smooth out the bottom of the slide, seriously they worked.

What do you think?

[Enginerd]

There are two differant lenghts of the 38mm Keihin Air Striker pwk 

I was planning to use a 96-97 KX250 factory carb.  I would guess its the longer of the two lengths.

[Enginerd]

I have used the 38 air striker on several bikes, I bored mine to 40.5 mm. I like the airstriker because it is much shorter and moves the slide closer to the piston, great throttle response. You will have to build a neck on the back of the carb as it is probably 1/2 to 3/4" shorter.

What is your reasoning for going to the 38mm? I've been using the Lectron one one of my bikes, but they seem to be dependant on what you have in your motor as to how well they work.

Don, thanks for the reply. My reason for considering the Airstriker swap is just as you stated. Better throttle response. My motor is stock except for a KIPS bolt, a thin head gasket, and an FMF Desert pipe with Power Core silencer. Bike runs great, and the FMF Desert really helped the top-end!  I thought I could get better response and get the quad vent setup at the same time.

I've also considered boring the Airstriker carb, and maybe having the horizontal divider plate added as well. Maybe something like this: http://www.rb-designs.com/bore-plate-carbs.htm

What do you think?

There is a company called starting line products, they make performance product for snowmobiles primarily, but, they had the divider plate setup you are talking about for a 39mm carb, in fact it is 2 plates and did work well. They had these long before companies like power now and others. Theirs was installed on the reed side of the carb where as some others are on both sides or on the inlet. There is something to turbulance and performance at the carb. On one of my old sleds it had Mikuni round slides. I bought a product that went in the bottom of the slide to smooth out the bottom of the slide, seriously they worked.

I'll look at what SLP offers.  The product that goes in the bottom of the slide on a Mikuni roundslide is called a UFO. I have one of those on the VM36 in my Bultaco Pursang.

[DoldGuy]

There are two differant lenghts of the 38mm Keihin Air Striker pwk 

I was planning to use a 96-97 KX250 factory carb.  I would guess its the longer of the two lengths.

Yes the 96/97 are the Original Style (Long) PWK, 99 & up are the short PWK (with electronics).

DoldGuy

[Enginerd]

There are two differant lenghts of the 38mm Keihin Air Striker pwk 

I was planning to use a 96-97 KX250 factory carb.  I would guess its the longer of the two lengths.

Yes the 96/97 are the Original Style (Long) PWK, 99 & up are the short PWK (with electronics).

DoldGuy

Also, I figure that OEM carbs may be better in terms of casting quality than non-OEM PWKs'.  Or is that a bad assumption?

[dave916]

[/quote]
DoldGuy
[/quote]Also, I figure that OEM carbs may be better in terms of casting quality than non-OEM PWKs'.  Or is that a bad assumption?
[/quote]
 The two on the are the short pwk{no electronics} all are OEM carb
http://i246.photobucket.com/albums/gg119/cr500-af/P1020453.jpg

[DoldGuy]

DoldGuy
[/quote]Also, I figure that OEM carbs may be better in terms of casting quality than non-OEM PWKs'.  Or is that a bad assumption?
[/quote]
 The two on the are the short pwk{no electronics} all are OEM carb
http://i246.photobucket.com/albums/gg119/cr500-af/P1020453.jpg

[/quote]

Not trying to Pee on the Bush but,

The two on the Left are not from a KX250 as 1999-2007 KX250 came with the "Short" PWK with Electronics (TPS/PJ) & the 1998 came with the "Long" style PWK with PJ & no TPS.
There were other Manufactures that came with the "Short" style PWK with no electronics but as stated not the KX250.

DoldGuy