Carb curious - not your normal ??

3 replies to this topic
  • jeepnrocks

Posted March 18, 2008 - 09:54 PM


Whats up all. Im new here and will be getting a WR very soon. I know a lot of people talk about the dreaded FCR bog and all the things you can do to cure it. From my experience with ATV's this bog was very odd. some bikes had it so bad that you would almost go over the bars whereas others had no hesitation at all. Anyhow my quad never came with an FCR (04 trx450R), so after coming across this site or JD jetting's site I found out about the 07 CRF 450 FCR and its improved accelerator pump circuit. I purchased this carb for my quad and never had to touch a thing. I tuned the pilot circuit slightly and rode. The throttle response was out of this world with no bog anywhere. I can't imagine any fuel injected atv having better throttle response. Anyhow, I just wondered if you had the specs and a multimeter if you could bolt that carb right up to a wr450F? I would think it wouldn't be a problem but I would like to hear from some of the experts.

  • William1

Posted March 19, 2008 - 02:15 AM


A few jets and a little tweaking will eliminate any bog. Basically, all FCR's are the same, it is the jets that are different.

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  • jeepnrocks

Posted March 19, 2008 - 04:11 AM


I know they are all very similar. I just wondered if one would bolt right up as long as you adjusted the TPS. I'm sure I will just do the mods but you never know when someone might have one of these carbs handy and would rather just bolt it on, heck it may even offer a performance gain.

  • William1

Posted March 19, 2008 - 05:44 AM


Almost all FCRs have the same outer diameter spigot mount to the engine. The intake side (Carb Bell) varies greatly. Some carbs have a removable bell and you can but the correct one, some do not. If the bell does not fit and is not removable, a few have had success at either modifying the existing one in a lathe or turning a collar. Many have met abject failure.

TPS is a very small part of the setup.

Almost never is a carb just a bolt on. To truly get it running right, jetting has to be done.


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