Dobeck or no Dobeck?
- Thread starter Cruisermy637
- Start date
as most have said yes add fuel but the Dobeck with the supplied Defeaters for the 02 Sensors moves the entire AFR fuel map into open circuit, its a lot more complicated than its used be , but the dobeck is one of the simplist and it works.
For reference Harleys as a rule and all bikes and cars for that matter do not actually run lean they run stometrically correct at 14.5/14.6 AFR which for the scientists amongst us is perfect burn ratio for normal run of the mill gasoline, the SE tuner has base maps for all ranges of fuel including the new high octane fuels and this drop down setting alters AFR/VE/Spark allowing again correct burn within the closed loop circuit of the fuel map which is were 99% ride which then allows the sensors to do their job of mapping the fuel within the parameters set in the ECU.
the heat is because of the Cats within the exhaust, yes adding fuel across the range will make the bike run seemingly better and cooler (like they used to, as carbs as rule run rich) because your pouring fuel into the system to act not only as the go juice but also as a coolant.
When i get my lappy back i will post up the maps from the SE tuner but for reference this is an image from toyota showing AFRs and a bit of other data, also here from people how make wide band stand alone sensors
SAFR - Standalone Air Fuel Ratio Diagnostic Tool
IDLE / LIGHT CRUISE: 13.5 AFR
When you start your vehicle we refer to this as being in IDLE condition. When you shift into gear and drive at a low mph we refer to this as being a LIGHT CRUISE driving condition. With 14.6 being the industry standard stoich AFR value, we typically like to see these conditions run slightly richer. We are looking to fine tune an engine to get the smoothest operation.
CRUISING: 14 AFR
Most of the time you are driving your vehicle you will be within the state of CRUISING. This condition is the most wide open for customer preference based on two factors. If you prefer better GAS MILEAGE then run a leaner mixture. Most stock to slightly modified engines will run just fine at an AFR of 15 and yield better MPG. If you prefer better PERFORMANCE then we suggest to run an AFR of 14 or even richer to around 13.
WIDE OPEN THROTTLE: 12.5 AFR
Driving full out within a gear will bring you into a WIDE OPEN THROTTLE driving condition. This condition is where the peak horsepower value is obtained. We typcially like to run a richer AFR here to get the best performance. Best performance for most vehicles is in the 12.5 to 13 AFR range. Going too rich will have the opposite affect and decrease your performance.
ACCELERATION: 12 AFR
Getting up to cruising speed or getting ready to pass someone, you usually are looking for the performance to get up and go. We refer to any fast turn of the throttle as being in an ACCELERATION driving condition. Again, we typcially like to run a richer AFR here to get the best performance. Best performance for most vehicles is around 12 AFR. Going too rich will cause a sluggish roll-on to get up to speed.
NOTE: OPTIMAL AFR VALUES WILL CHANGE BASED ON FORCED AIR INDUCTION VS NATURALLY ASPIRATED AND FUEL TYPES
For reference Harleys as a rule and all bikes and cars for that matter do not actually run lean they run stometrically correct at 14.5/14.6 AFR which for the scientists amongst us is perfect burn ratio for normal run of the mill gasoline, the SE tuner has base maps for all ranges of fuel including the new high octane fuels and this drop down setting alters AFR/VE/Spark allowing again correct burn within the closed loop circuit of the fuel map which is were 99% ride which then allows the sensors to do their job of mapping the fuel within the parameters set in the ECU.
the heat is because of the Cats within the exhaust, yes adding fuel across the range will make the bike run seemingly better and cooler (like they used to, as carbs as rule run rich) because your pouring fuel into the system to act not only as the go juice but also as a coolant.
When i get my lappy back i will post up the maps from the SE tuner but for reference this is an image from toyota showing AFRs and a bit of other data, also here from people how make wide band stand alone sensors
SAFR - Standalone Air Fuel Ratio Diagnostic Tool
IDLE / LIGHT CRUISE: 13.5 AFR
When you start your vehicle we refer to this as being in IDLE condition. When you shift into gear and drive at a low mph we refer to this as being a LIGHT CRUISE driving condition. With 14.6 being the industry standard stoich AFR value, we typically like to see these conditions run slightly richer. We are looking to fine tune an engine to get the smoothest operation.
CRUISING: 14 AFR
Most of the time you are driving your vehicle you will be within the state of CRUISING. This condition is the most wide open for customer preference based on two factors. If you prefer better GAS MILEAGE then run a leaner mixture. Most stock to slightly modified engines will run just fine at an AFR of 15 and yield better MPG. If you prefer better PERFORMANCE then we suggest to run an AFR of 14 or even richer to around 13.
WIDE OPEN THROTTLE: 12.5 AFR
Driving full out within a gear will bring you into a WIDE OPEN THROTTLE driving condition. This condition is where the peak horsepower value is obtained. We typcially like to run a richer AFR here to get the best performance. Best performance for most vehicles is in the 12.5 to 13 AFR range. Going too rich will have the opposite affect and decrease your performance.
ACCELERATION: 12 AFR
Getting up to cruising speed or getting ready to pass someone, you usually are looking for the performance to get up and go. We refer to any fast turn of the throttle as being in an ACCELERATION driving condition. Again, we typcially like to run a richer AFR here to get the best performance. Best performance for most vehicles is around 12 AFR. Going too rich will cause a sluggish roll-on to get up to speed.
NOTE: OPTIMAL AFR VALUES WILL CHANGE BASED ON FORCED AIR INDUCTION VS NATURALLY ASPIRATED AND FUEL TYPES
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dolt
Well-Known Member
Personally, I would opt for the TTS Mastertune and a proper dyno tune. Sure, a little more expensive but truly the only way to optimize performance from idle to WOT and everywhere in between; but that's me.
Having said that, if I were to opt for a Dobeck system, I would have to add the AFR meter to the package and eliminate the AFR guess work. That would be the SAFR meter referred to in Hobbit's post. If I didn't have cheap access to dyno time, I would have the SAFR meter installed on my carbureted all bore 107" in my '02 FLHT to fine tune the carb.
One last comment. Forget about stoichiometric, or 14.7 AFR as it is just not practical with an air cooled vtwin Harley. If one desires a cool running motor, an AFR of 13.5-13.8 is about where the AFR should be. Water cooled motors can run leaner at cruise; they can handle the additional heat a lean AFR will generate. You have to give the motor what it wants.:newsmile07:
Having said that, if I were to opt for a Dobeck system, I would have to add the AFR meter to the package and eliminate the AFR guess work. That would be the SAFR meter referred to in Hobbit's post. If I didn't have cheap access to dyno time, I would have the SAFR meter installed on my carbureted all bore 107" in my '02 FLHT to fine tune the carb.
One last comment. Forget about stoichiometric, or 14.7 AFR as it is just not practical with an air cooled vtwin Harley. If one desires a cool running motor, an AFR of 13.5-13.8 is about where the AFR should be. Water cooled motors can run leaner at cruise; they can handle the additional heat a lean AFR will generate. You have to give the motor what it wants.:newsmile07:
Lucky Doug
Member
I got the original Dobeck TFI second hand and it does as intended. I have full stage 1 on my 07 Street Bob and wanted to adjust my fuel ratios to my liking. I don't care if it is super tuned and I am not going to put in on a dyno. Installation was easy and I can tune it by ear and adjust on the road if necessary (never needed too). Perfect for me and will probably do the same thing on my next bike.