Not sure what FCR I have ?

Can anyone identify this carb ? Will it work on the SM?





This port is what's confusing me?


I really cant ID that carb, sorry, way to many possibilities..
I can say from looking at the pics, JB weld on the carb body, RTV gunked on the cap and choke pull and around the air boot adapter I would sooner use that carb as a wheel chock then a carburetor.

Will it fit? Might will it work correctly if it fits? not by looking at it...... 
Measure the head side and air boot side.. Measure the bore..what size?
Look at the slide, vacuum reseal plate and seal  for wear and or damage.
Look at the carb body where the slide wheels contact, is it worn? grooved?
Is there play in the throttle wheel shaft? (Common on older carbs and thats a vac leak you can not reasonable fix)

I think I've seen the Yamaha WR426F FCR had that 90° vent but I'm not 100% sure.


While buying a used carburetor isn't necessarily bad, (all carbs are used as soon as fuel goes in the bowl) you definitely need to be cautious. MX bikes have been FI for almost 10 years now so the supply is aging. Keep in mind, well kept machines generally don't get parted out. I can just imagine what the rest of the bike that carb originated looked like.


Secondly, nearly all the questions about FCR jetting are from people with used carbs. I've tried 1 used FCR and 2 brand new. The brand new carbs ran cleanly following the typical jet recommendations on the site. Might not of been optimal but was more than ridable. The used FCR needed something very different to run decent, likely due to body wear as Eric described.


There is also the KLR carb option that will provide similar gains without shelling out nearly a grand for a new FCR.






Looks like it has a removable bell, but the vent is different than the TT-Sudco.

Here’s s pic of my FCR39MX from Sudco for example...



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