Rotax Jetting Range for the Midwest - Again

tony zambos · 04-07-2010, 09:14 PM

What would be the greatest range of jets would I likely need for an 09 Rotax Sr and do I need to have every jet within that range? Planning on sprint racing in Indiana and Illinois, and road racing in MI, WI and IL. A search showed that Chris Lobaugh answered this question back in 2008 with a range between 155 and 168. Have heard that with the 09 motor, the bottom of the range might be as low as a 140.

Thanks in advance,
tony

Chris Lobaugh · 04-09-2010, 11:03 AM

140 sounds a little lean for the midwest but with the new style airbox it possible that you might go as low as 145

Chris Lobaugh · 04-09-2010, 11:07 AM

probably don't need to have every jet...at least not to begin with. A common jet kit would be 145, 148, 150, 152, 155, 158, 160, 162, 165, 168.

tony zambos · 04-09-2010, 04:22 PM

Thanks Chris. I am assuming that the temp on the day we get to break the engine in will be in the 60's. We're going to be using Marc's break-in procedure. I'm also assuming that a new engine will come with a 168 jet and that should be on the rich side, but OK for break in.

04-07-2010, 09:14 PM	#1
tony zambos Rookie Join Date: Feb 2010 Posts: 3	Rotax Jetting Range for the Midwest - Again What would be the greatest range of jets would I likely need for an 09 Rotax Sr and do I need to have every jet within that range? Planning on sprint racing in Indiana and Illinois, and road racing in MI, WI and IL. A search showed that Chris Lobaugh answered this question back in 2008 with a range between 155 and 168. Have heard that with the 09 motor, the bottom of the range might be as low as a 140. Thanks in advance, tony

04-09-2010, 11:03 AM	#2
Chris Lobaugh Birel Specialist / Engineer Join Date: Jan 2008 Posts: 237	140 sounds a little lean for the midwest but with the new style airbox it possible that you might go as low as 145 __________________ Chris Lobaugh Birel Engineer & Specialist chris@mrpmotorsport.com

04-09-2010, 11:07 AM	#3
Chris Lobaugh Birel Specialist / Engineer Join Date: Jan 2008 Posts: 237	probably don't need to have every jet...at least not to begin with. A common jet kit would be 145, 148, 150, 152, 155, 158, 160, 162, 165, 168. __________________ Chris Lobaugh Birel Engineer & Specialist chris@mrpmotorsport.com

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04-09-2010, 04:22 PM	#4
tony zambos Rookie Join Date: Feb 2010 Posts: 3	Thanks Chris. I am assuming that the temp on the day we get to break the engine in will be in the 60's. We're going to be using Marc's break-in procedure. I'm also assuming that a new engine will come with a 168 jet and that should be on the rich side, but OK for break in.