KX Riders

Maintenance & Technical => KX500 Original => Topic started by: IridiumRed on March 13, 2005, 06:57:49 PM

Title: FCR Carb on KX500?
Post by: IridiumRed on March 13, 2005, 06:57:49 PM

Hey Guys

Love the site.  I recently bought a 97 KX500 (due in no small part to what i read here!!)

question - I've got a Keihin FCR41 (41 mm flatslide race carb..... basically as nice as carbs get!!).  I bought it to use on my KLX650 dual purpose bike, but now i'm wondering, could I use this on the KX500?

I know i'd have to screw with the jetting, but i wonder if it would help with some of the jetting issues that the KX500 is known for??  It has a large (but somewhat adjustable) accelerator pump built in.....

I'm new to 2strokes (know a bit about 4 strokes), and I know that the FCR's are LOVED on 4strokes, but never heard of someone using one on ANY 2 stroke............

Of course, the 41 might be too big, but I could always get a 37 or 39.... they're way easier to find anyways

thanks!!

Title: FCR Carb on KX500?
Post by: Timbowe on March 13, 2005, 07:16:34 PM

Not sure bout the 500 but I know those carbs are the bees knees on my Duc S/L. Years ago some of the boys used to put 2 stroke carbs on some of the big bore 4 strokes. Was a popular mod. I'm sure some one here will have the answer for you. Cant wait to find out myself!

Title: FCR Carb on KX500?
Post by: gowen on March 13, 2005, 11:12:32 PM

I am unsure about the exact carb you speak of, but I have a carb for my 500 that is a 41mm Kehin PWK. Something like that would be better posted on Dirtrider.net for the guru Rich Rohrich to answere.

Title: FCR Carb on KX500?
Post by: KXcam22 on March 14, 2005, 04:49:47 AM

IR,
  Might be fun to try.  I suspect you will have to disable the accelerator pump. 2-strokes typically don't need them. Have fun. Cam.

Title: FCR Carb on KX500?
Post by: IridiumRed on March 14, 2005, 07:47:27 AM

yeah, the accelerator pump could be disconnected, that actually probably wouldn't be too hard.....

i really dont know if an FCR would work on a 2 stroke, but I know with 4 strokes, the FCR is king of the hill.  There are flatslides similar to the PWK (hell, maybe varieties of the PWK will work on a 4 stroke too), but the FCR performs a lot better.

The PWK just looks like a dated design to me (and thats only my opinion and i could be way off).  The FCR has a slide that is supported on rollers for very low friction, for example - but of course, thats so that the slide isn't really hard to open due to engine vacuum, but.... maybe thats just not as big of a deal with a 2stroke.....

Title: FCR Carb on KX500?
Post by: Arigato on March 16, 2005, 02:59:47 PM

I think that because of the different intake velocities, the FCR would not work nor would it be necessary.  If you have your PWK bored to 41mm you would be better off.

Title: FCR Carb on KX500?
Post by: gowen on March 16, 2005, 03:30:18 PM

Arigato is right, I would have a tapered bore though, it saves a hell'ova lot of jetting.