keihin main jet Q??

cuz · September 10th, 2011, 08:33 AM

i bought in advance removing the air-box 2X 112 keihin main jets at my local motorcycle store but the ones she gave me are the long type and not the circle short one will they still work? well txs

kbryant · September 10th, 2011, 11:25 AM

The long ones are for FCR and some Harley Carbs. The OEM short style ones are for CV/CVK models (your 250r).

I did testing on substituting long and short Keihin main jets many years ago, and I don't actually recall it making any difference on the Dyno. But obviously the FCR style is twice as long as your OEM main jet, so this is wrong. The bottom line is that you should get the correct style (short) main jets for the OEM 250r CV carbs.

k-os · September 10th, 2011, 01:52 PM

Quote:

Originally Posted by kbryant

The long ones are for FCR and some Harley Carbs. The OEM short style ones are for CV/CVK models (your 250r).

I did testing on substituting long and short Keihin main jets many years ago, and I don't actually recall it making any difference on the Dyno. But obviously the FCR style is twice as long as your OEM main jet, so this is wrong. The bottom line is that you should get the correct style (short) main jets for the OEM 250r CV carbs.

I'd think that the longer jets could be a problem if your float height isn't set right, or if it contacts the covers for the float bowls.

greatwhiteninja · September 10th, 2011, 08:27 PM

I'd use what's in there .. the short ones, Jetsrus.com can't go wrong

September 10th, 2011, 08:27 PM	#4
greatwhiteninja Ridin Dirty Name: Ed Location: Delaware Join Date: Jun 2011 Motorcycle(s): 2011 white se 250r , 2008 zx6R Posts: 921	I'd use what's in there .. the short ones, Jetsrus.com can't go wrong __________________________________________________ #1

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September 10th, 2011, 11:25 AM	#2
kbryant Area P Name: Kerry Location: SoCal & South Florida Join Date: Dec 2008 Motorcycle(s): Too many to list Posts: 439	The long ones are for FCR and some Harley Carbs. The OEM short style ones are for CV/CVK models (your 250r). I did testing on substituting long and short Keihin main jets many years ago, and I don't actually recall it making any difference on the Dyno. But obviously the FCR style is twice as long as your OEM main jet, so this is wrong. The bottom line is that you should get the correct style (short) main jets for the OEM 250r CV carbs.