Which Floats and pilots are seeming to work better with New JR 09 package???

bubba53 · 11-06-2009, 09:33 AM

Hell just picked up a new 09 Rotax JR package, has the new clutch, reed cage, coil, and exhaust flange. Wondering what floats most are useing with the JR pacakge. Comes with the Lights and 60 pilots.
I know in the senior package we had the best luck with the heavy floats.
Thanks Bub

Marc Miller · 11-06-2009, 08:01 PM

Hey Bubba-

I believe this really depends on the driver. The 3.6 floats seem to make it more user friendly for drivers with a quick/heavy throttle foot (that are used to yamaha or most other kart engines). The 5.2 floats take a little more patience.

Overall - it comes down to testing the difference with your driver, looking at a little data and see which one yields the better results. Also keep in mind, one set of floats might make the best lap time, but in racing conditions, if the driver can't stay calm and roll the throttle smoothly in the heat of the moment, the overall performance might suffer.

Again - it comes down to doing a little testing.

Best of luck and contatc us if you have more questions!

Bob Francis · 11-06-2009, 08:23 PM

Depends on the current weather info and air quality. Both set ups can work very well.

jrancini · 01-08-2011, 06:02 PM

Hey mark i have a MiniMax driver, what do you mean by " roll on the throttle" ? i thought it was full on gas or on brake, is it different with minimax? thanks

Jonny

Bruce Woodrow · 01-09-2011, 09:37 PM

Jonny,

It is different for all Rotax FR125 engines that use a fully operational Dellorto VHSB34 carb. (Minimax, Junior, Senior and DD2). The difference with this engine/carb. combination is that the carb. is really oversized for the engine. The result is that if you suddenly snap the throttle open, the air velocity in the measuring section of the carb. drops too low to provide a good 'signal'. Consequently, the air/fuel mixture suffers and the atomization of the fuel is also poor, leading to poor engine response. (This is true to some extent for any carburetted engine, but the effect is exaggerated by the FR125's oversized carb.)

So, it is much better to steadily open the throttle as the engine speed rises, maintaining higher air velocity in the measuring section of the carb., leading to much better response.

I have deliberately not called this difference a 'problem' or 'issue', as that would, quite rightly, upset Marc, who will tell you that this is actually a great feature of the Rotax FR125/VHSB34 combination. This is because it rewards/teaches excellent throttle control, which can be usefully applied at any level of motorsport.

Bruce

Garry Lobaugh · 01-10-2011, 03:13 AM

Well done Bruce!

It is great to hear from you. When will you visit the US next? We are preparing for an outstanding season in Rotax.

jrancini · 01-11-2011, 01:53 PM

Makes sense Bruce, thank you for your input, it will help me alot with my Junior driver. thanks

Marc Miller · 01-13-2011, 11:22 AM

Couldn't have said it better Bruce. Experienced drivers and driver coaches use this term a lot. It is an important thing to learn to do if you wish to race cars and no other kart engine/class rewards it like the Rotax.

jrancini · 01-26-2011, 01:09 PM

i am having trouble explaining the "Rolling of throttle" concept to my cadet driver. the driver understand there should be a gradual throttle, however, how gradual? hom much On throttle? let say we have a 750' straight how long should it take for the driver to be on "full throttle"?? should it take 1/2 way down straight?, 3/4 way down straight? or end of straight?

thanks Jonny

Clay Maddox · 01-31-2011, 09:15 AM

One way I explain the Rotax driving style to new Rotax people is, "Let the engine tell you when it is ready for more throttle versus the driver telling the engine when it is ready for more throttle."

11-06-2009, 09:33 AM	#1
bubba53 Rookie Join Date: Mar 2008 Posts: 8	Which Floats and pilots are seeming to work better with New JR 09 package??? Hell just picked up a new 09 Rotax JR package, has the new clutch, reed cage, coil, and exhaust flange. Wondering what floats most are useing with the JR pacakge. Comes with the Lights and 60 pilots. I know in the senior package we had the best luck with the heavy floats. Thanks Bub

11-06-2009, 08:01 PM	#2
Marc Miller Birel & Rotax Specialist Join Date: Jan 2008 Posts: 850	Hey Bubba- I believe this really depends on the driver. The 3.6 floats seem to make it more user friendly for drivers with a quick/heavy throttle foot (that are used to yamaha or most other kart engines). The 5.2 floats take a little more patience. Overall - it comes down to testing the difference with your driver, looking at a little data and see which one yields the better results. Also keep in mind, one set of floats might make the best lap time, but in racing conditions, if the driver can't stay calm and roll the throttle smoothly in the heat of the moment, the overall performance might suffer. Again - it comes down to doing a little testing. Best of luck and contatc us if you have more questions! __________________ Marc Miller Director of Brand Development MRP Motorsport/Birel

01-13-2011, 11:22 AM	#8
Marc Miller Birel & Rotax Specialist Join Date: Jan 2008 Posts: 850	Couldn't have said it better Bruce. Experienced drivers and driver coaches use this term a lot. It is an important thing to learn to do if you wish to race cars and no other kart engine/class rewards it like the Rotax. __________________ Marc Miller Director of Brand Development MRP Motorsport/Birel

01-26-2011, 01:09 PM	#9
jrancini Rookie Join Date: Sep 2008 Posts: 25	i am having trouble explaining the "Rolling of throttle" concept to my cadet driver. the driver understand there should be a gradual throttle, however, how gradual? hom much On throttle? let say we have a 750' straight how long should it take for the driver to be on "full throttle"?? should it take 1/2 way down straight?, 3/4 way down straight? or end of straight? thanks Jonny Last edited by jrancini; 01-26-2011 at 01:41 PM.

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11-06-2009, 08:23 PM	#3
Bob Francis Rookie Join Date: Jan 2008 Posts: 6	Depends on the current weather info and air quality. Both set ups can work very well.

01-08-2011, 06:02 PM	#4
jrancini Rookie Join Date: Sep 2008 Posts: 25	Hey mark i have a MiniMax driver, what do you mean by " roll on the throttle" ? i thought it was full on gas or on brake, is it different with minimax? thanks Jonny

01-09-2011, 09:37 PM	#5
Bruce Woodrow Rookie Join Date: Jan 2008 Posts: 37	Jonny, It is different for all Rotax FR125 engines that use a fully operational Dellorto VHSB34 carb. (Minimax, Junior, Senior and DD2). The difference with this engine/carb. combination is that the carb. is really oversized for the engine. The result is that if you suddenly snap the throttle open, the air velocity in the measuring section of the carb. drops too low to provide a good 'signal'. Consequently, the air/fuel mixture suffers and the atomization of the fuel is also poor, leading to poor engine response. (This is true to some extent for any carburetted engine, but the effect is exaggerated by the FR125's oversized carb.) So, it is much better to steadily open the throttle as the engine speed rises, maintaining higher air velocity in the measuring section of the carb., leading to much better response. I have deliberately not called this difference a 'problem' or 'issue', as that would, quite rightly, upset Marc, who will tell you that this is actually a great feature of the Rotax FR125/VHSB34 combination. This is because it rewards/teaches excellent throttle control, which can be usefully applied at any level of motorsport. Bruce

01-10-2011, 03:13 AM	#6
Garry Lobaugh MRP Motorsport - President Join Date: Jan 2008 Posts: 1,780	Well done Bruce! It is great to hear from you. When will you visit the US next? We are preparing for an outstanding season in Rotax.

01-11-2011, 01:53 PM	#7
jrancini Rookie Join Date: Sep 2008 Posts: 25	Makes sense Bruce, thank you for your input, it will help me alot with my Junior driver. thanks

01-31-2011, 09:15 AM	#10
Clay Maddox Rookie Join Date: Jan 2008 Posts: 31	One way I explain the Rotax driving style to new Rotax people is, "Let the engine tell you when it is ready for more throttle versus the driver telling the engine when it is ready for more throttle."