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FCR39 on a standard bike

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Hi guys.. I just got a FCR 39 carb, originally off a KTM. So you know its the newer style and not the slanted body, has choke but no hot start and it does have TPS. No coast enrichener thing.

I'm looking to jet it to run on a standard SM exhaust (only for the moment but getting a system is a few months off). I will be modifying the airbox, most likely beyond the 3x3 but otherwise standard engine.

As base/get it running jetting I was going to run standard E model (UK spec) jets all round. I'll be running it on our dyno at work so should be able to correct things but wanted a ball park idea before I installed the carb.

Thanks in advance for any reccomendations. :confused:

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if you plan on modifying the air box beyond 3x3,you are pretty much on your own.

you have a dyno,strap it down and make some pulls.

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I have a good idea for which jets to try first.. After some searching around I'm going with:

155 Main Jet

45 Pilot Jet

65 Starter Jet

100 Pilot Air Jet

200 Main Air Jet

EMN Needle Clip 3 or 4

Will order some other jets at the same time just so I have options.

Couple of questions if I may Eddie (or anyone else for that matter :confused: ), what effects on fueling do the pilot and main air jets have (I wondered where they work in terms of throttle postion).

Also, is the E model intake bell 60mm (2 3/8"), want to know if it will fit into the SM airbox rubber or if I should order an adapter from TT (I'm in the UK otherwise I would have ordered one already).

Thanks, Rich

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the E model intake bell only works with the E model air boot.

pilot air jet works in conjunction with the pilot jet and fuel screw.idle and just off idle.like 1/16 throttle.

the main air jet controls the mixture at wot like the main jet but at lower end of the rpm scale.

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I have a good idea for which jets to try first.. After some searching around I'm going with:

155 Main Jet

45 Pilot Jet

65 Starter Jet

100 Pilot Air Jet

200 Main Air Jet

EMN Needle Clip 3 or 4

Will order some other jets at the same time just so I have options.

Couple of questions if I may Eddie (or anyone else for that matter :confused: ), what effects on fueling do the pilot and main air jets have (I wondered where they work in terms of throttle postion).

Also, is the E model intake bell 60mm (2 3/8"), want to know if it will fit into the SM airbox rubber or if I should order an adapter from TT (I'm in the UK otherwise I would have ordered one already).

Thanks, Rich

hey Rich

what is your altitude ??

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hey Rich

what is your altitude ??

Sea level, same as everyone else in the UK :confused:

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This is the UK mate, we don't really have any altitude!! lol

Approx 200 feet so call it sea level-1000ft

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Oh, and you should really remove the Pilot Air jet.

Hey Headster.. Saw that mentioned somewhere else, why does it need removing dude?

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Hey Headster.. Saw that mentioned somewhere else, why does it need removing dude?

If its installed you have to start dropping Pilot jets by big numbers.

Off memory some people went down into the 30's

Remove the PAJ and the 45 Pilot is perfect :confused:

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what about wales :confused:

I didnt know it was possible to jet for 0 - 200ft underwater :excuseme: :excuseme:

okay parts of wales and scotland might just be over 1000 ft

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thats only on the aftermarket fcr-mx.

he has the old stlye fcr.needs a 100 pilot air jet installed.

Oh woops.

My Bad. :confused:

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the E model intake bell only works with the E model air boot.

If I got the intake bell and the E model air boot will the air boot fit the SM airbox?

Its almost ready to go in but I'm going to New Zealand for a few weeks and I won't be able to play now for a month!! Sucks big time!!

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