Keihin Carb. Size

I recently purchased a 2003 KTM 450 EXC. My understanding is that the stock carb is an FCR MX39. I went to pull out the Power Now off a 2005 WR450 and place it intothe KTM. The KTM carb opening was too big. I thought both bikes have the same carb.

How can I tell which carb. (maybe the FCR MX41) I have on the KTM. Does the serial number on the outside give any clues?:thumbsup:

You are correct, they both should have the same carb from what I can see. Maybe someone swapped out the KTM carb?

I recently purchased a 2003 KTM 450 EXC. My understanding is that the stock carb is an FCR MX39. I went to pull out the Power Now off a 2005 WR450 and place it intothe KTM. The KTM carb opening was too big. I thought both bikes have the same carb.

How can I tell which carb. (maybe the FCR MX41) I have on the KTM. Does the serial number on the outside give any clues?:thumbsup:

Marty, stock is fcr 39. All fcr's have the same od on the engine intake side- different id's (maybe not the 41). However, on the otherside that faces the airbox- there is a bolt on air bell. There are different sized Od's for different bikes- Some fcr carbs for OEM do not have a removable bell. Your original carb has a removable bell.

your Power Now fits inside the air bell ( on the airbox side). There might be a slight varrience in ID between the Yama and the Ktm Id, the Od's are commonly different....

Good answer from DRZ

Within the KTM family 41s all have the Hot Start (red knob) on the left side and yes they fit the intake spigot the same. Simple way to tell 39 from 41, looking at it from the engine side the part that goes into the rubber spigot the hole in the center is symetrical or centered on the 41 and bored below center on the 39.

Also that rear air bell was bolt on on all KTMs up thru 05, but Yamaha gets new stuff before KTM, in 06 KTM got the newer style with the air bell being one piece, Yamaha may have gotten it on 05?

Thanks DRZ. So on the KTM, the opening facing the airbox needs to be removed and then the Power Now fits. Afterwards, bolt the removed bell back on. The WR carb permitted the Power Now to fit right on without taking anything off.

Thanks DRZ. So on the KTM, the opening facing the airbox needs to be removed and then the Power Now fits. Afterwards, bolt the removed bell back on. The WR carb permitted the Power Now to fit right on without taking anything off.

Hey,

I actually don't own a powernow and haven't installed one or seen instructions-I assume it's supposed to slide into the bell (while the bell is on the carb)

You'll have to look at it- 'how was it installed on your WR? The Ktm is no different- in that reguard. My thing was the bell off the wr and the bell off your ktm probably are different ID's and the powernow is made for the WR is not transferrable to the Ktm, so it won't fit. I looked it up and they list different Part number's for both bikes- so there is a difference.

Get out a file and trim it a little, or sell it.

Hey,

I actually don't own a powernow and haven't installed one or seen instructions-I assume it's supposed to slide into the bell (while the bell is on the carb)

You'll have to look at it- 'how was it installed on your WR? The Ktm is no different- in that reguard. My thing was the bell off the wr and the bell off your ktm probably are different ID's and the powernow is made for the WR is not transferrable to the Ktm, so it won't fit. I looked it up and they list different Part number's for both bikes- so there is a difference.

Get out a file and trim it a little, or sell it.

The Power Now for that model replaced the rear bell of the carb, simple 2 bolt bolt on once the carb is off. In 06 the bell became built in and the slip inside style began

The Power Now for that model replaced the rear bell of the carb, simple 2 bolt bolt on once the carb is off. In 06 the bell became built in and the slip inside style began

Ok, I just thought the PowerNow Plus replaced the bell, and the powernow was the plate insert style.

Yep, I just found that out as I took out the carb., pulled of the bell housing, and it didn't fit. Oh well. I sure wish the carbs were as easy as Legos to take apart and snap back in place. I am selling this Power Now or even better trade it for one that fits my KTM.

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