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Help needed re fcr33 jets where to start?

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Nobbsie

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Help needed re fcr33 jets where to start?

PostSun Sep 24, 2017 8:07 pm

Hello everyone,
Been searching the old posts but can't seem to bring up anything.
I have a standard rm gk76a, it has standard pipes and exhaust but does have the k&n.
I see for the standard people suggest around a 115 main ish,
But does anyone know a ball park to start with the fcrs?
I got the fcrs cheap with no main jets,
Cheers
Nobbsie
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moforockband

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  • Bike owned: GK73a SP CRM250 mk3

Re: Help needed re fcr33 jets where to start?

PostWed Sep 27, 2017 10:41 am

I had 185/190 in a ram air fcr33 zxr400. But that had a large ram air airbox.
On a std bike, I think you will struggle with carbs as large as that. I would start at 95 with a std airbox, and work from there. An fcr33 is designed to flow A LOT of air, and running them at low air volumes/speeds usually ends with problems.
I sent my bike back to the tuner who custom fab'd some air deflectors to fit over the intakes, just so I could get some flexibility at low revs.
I noticed that I could only ever set the bike up to run when the engine was hot. If I went out on track from cold it ran like a BOS, and always threatened to foul a plug. But when hot, it was usually the fastest bike out there!
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Nobbsie

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Re: Help needed re fcr33 jets where to start?

PostWed Sep 27, 2017 9:42 pm

Thanks I'll start from there, what size slow jets did you run?
It will not stay standard for long, just brought these first as they where super cheap.
Have you used the ebc jets? Was thinking about just buying a dealer kit and getting it over with?
Cheers
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moforockband

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Re: Help needed re fcr33 jets where to start?

PostWed Sep 27, 2017 11:06 pm

I can't remember what the other jets were. I only leaned off the top end at the track when it was raining. EBC jets are ok for std carbs, but I would stick to Keihin genuine jets for the fcr's.
I'd decide on the spec of your set-up 1st, and get it built, then sort the carbs. FCR's are a real bitch to get right, and you only want to do it once, trust me, it gets expensive :D
Do you have the ones with the choke?
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Nobbsie

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Re: Help needed re fcr33 jets where to start?

PostTue Oct 10, 2017 8:54 pm

Perfect I guess I'll try get genuine jets for it!
Can't wait to get them on the bike!!!

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