Carb Jet sizes help.

Andy B · 16-12-2018, 05:13 PM

Hi guys, doing a bit of TLC on the 900.

Its been burning oil since buying it in the first place, and i've kind of been putting off fixing it until now, and whilst i'm in there i decided to give the carbs a going over with too..

I actually bought new carbs shortly after buying the bike as I was convinced it was running rich, and the mixture screws were seized solid.

I still have the old carbs (i like keeping spares) and curiosity made me compare the two for jet sizes..

The carbs that came on the bike have 144 main jets, and 40 pilot jets.

The new carbs I bought have 127.5 mains and 42.5 pilots...

(i havent checked the needle position yet)

So I guess, first question is, does anyone know what the stock jet sizes is for a 900?

Thanks in advance for any info

Dennis menace · 17-12-2018, 10:10 AM

According to Haynes (for models made between 91-96) the main jet is 140, main air jet is 70, needle jet is Y-2, needle is 5C19 - 4th notch from the top, pilot jet is 40 and pilot air jet is 60/1.4.

Andy B · 17-12-2018, 04:13 PM

Brill, thanks very much.. bit odd with the 127.5 then, might throw the 144 in and see how she behaves once the piston rings have been sorted...

16-12-2018, 05:13 PM	#1
Andy B Registered User Join Date: Sep 2014 Location: Bromborough Bike: M900 Posts: 94	Carb Jet sizes help. Hi guys, doing a bit of TLC on the 900. Its been burning oil since buying it in the first place, and i've kind of been putting off fixing it until now, and whilst i'm in there i decided to give the carbs a going over with too.. I actually bought new carbs shortly after buying the bike as I was convinced it was running rich, and the mixture screws were seized solid. I still have the old carbs (i like keeping spares) and curiosity made me compare the two for jet sizes.. The carbs that came on the bike have 144 main jets, and 40 pilot jets. The new carbs I bought have 127.5 mains and 42.5 pilots... (i havent checked the needle position yet) So I guess, first question is, does anyone know what the stock jet sizes is for a 900? Thanks in advance for any info

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17-12-2018, 10:10 AM	#2
Dennis menace Registered User Join Date: Nov 2013 Location: Farnsfield Bike: Other Ducati Posts: 300	According to Haynes (for models made between 91-96) the main jet is 140, main air jet is 70, needle jet is Y-2, needle is 5C19 - 4th notch from the top, pilot jet is 40 and pilot air jet is 60/1.4.

17-12-2018, 04:13 PM	#3
Andy B Registered User Join Date: Sep 2014 Location: Bromborough Bike: M900 Posts: 94	Brill, thanks very much.. bit odd with the 127.5 then, might throw the 144 in and see how she behaves once the piston rings have been sorted...