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Booster Plug or Rapid Bike Easy?

26K views 78 replies 22 participants last post by  KTMasean 
#1 ·
I want to cure the low down jerkiness of my standard Duke 390. I am looking at two options based on functionality and price: Either the Booster Plug (cheapest option) or the Rapid Bike Easy (has a bit more adjustability). Has anyone here more real time on the road info of any of the two devices mentioned? Regards!
 
#69 ·
my bike is 2016 model and it was literally impossible to maintain 8 mph smoothly in 1st gear without using the clutch, with the boosterplug fitted it is now possible,
it was also impossible to maintain 12 or 15 mph in second gear smoothly without using the clutch, again it is now possible,
changing final gearing ratios would not change how my bike reacted at tiny throttle openings, when you change gearing you can only change so far until 1st gear effectively becomes the same as the standard 2nd gear, basically like losing the standard 1st gear,
if changing the gearing on your bike helped then that is great, but don't assume one method will help in all cases, check out youtube videos to see how many brands of bike get improved low rpm running according to their owners by fitting such devices,
maybe this engine is as it is at low rpm running is because it was destined to be in an off road bike where it would be used hard,
you also have to remember that we are from different countries and our atmospheres and air qualities may be better or worse than others for our bikes which will make them behave differently, also the quality of fuel may differ from country to country
 
#70 ·
my bike is 2016 model and it was literally impossible to maintain 8 mph smoothly in 1st gear without using the clutch, with the boosterplug fitted it is now possible,
it was also impossible to maintain 12 or 15 mph in second gear smoothly without using the clutch, again it is now possible,
changing final gearing ratios would not change how my bike reacted at tiny throttle openings, when you change gearing you can only change so far until 1st gear effectively becomes the same as the standard 2nd gear, basically like losing the standard 1st gear,
if changing the gearing on your bike helped then that is great, but don't assume one method will help in all cases, check out youtube videos to see how many brands of bike get improved low rpm running according to their owners by fitting such devices,
maybe this engine is as it is at low rpm running is because it was destined to be in an off road bike where it would be used hard,
you also have to remember that we are from different countries and our atmospheres and air qualities may be better or worse than others for our bikes which will make them behave differently, also the quality of fuel may differ from country to country
16's are different bud, I have a 16 and the fueling issues are def real with them.
 
#72 ·
Gen 1 bikes were definitely rougher at low revs but whilst KTM smoothed out the low end of the gen 2 map I’m not convinced that they made it less lean. The gen 1 bikes are reported to faster. I suspect all KTM did was to smooth off the power peaks at low revs, reducing the fuel input and making it smoother but slower. On a gen 2 bike nothing exciting happens at low revs.
 
#74 ·
Ive owned both Gen 1 and Gen 2 390's and riden them both un modified and fettled ...... the Gen 1 out the box was lumpy bumpy and jerky as fruck ..... then you go on that journey to get it be nice to live with on a day to day basis - for me it involved a -3 rear sprocket - it was good but the bike still needed more fiddling with..... then had internal parts of the zorst removed by the KTM Dealer (bit louder but not crazy) and then they re-mapped it - quoting a " plus 6hp" increase ..... you certainly could feel the difference and it was much much smoother and easier to live with - would it be faster than my Gen 2 - with -4 sprocket and k and n filter ? god only knows .... almost a year appart for one ..... all toll'd - the Gen 2 is a much much improved version of the 390 and imho, needs minimal faffing with compared to the Gen 1 .......if you were today looking to get a s/h 390 - i'd recommend giving the Gen 1 a wide birth and going for the Gen 2 ....
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When the 490 hits the shores later this year, you can bet your bottom dollar that it will be a huge improvement over the Gen 2 390 ......
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#76 · (Edited)
Hi guys, I've just been riding around the my new duke and while i find it lurchy in 1st (and think a 16T would prob help with that). I still find it's pretty touchy even when just cruising in third etc. Did the Booster or RPE help much here ? I think alot of this is just how fuel injection works (very responsive). I'm used to a carby'd dirtbike...
 
#79 ·
A thing to consider with the Booster Plug is that due to the way this functions it will increase the amount of fuel regardless.
This means that in the closed-loop you'd probably be okay BUT in the open-loop, where KTM engines often run too rich the Booster-Plug will worsen this situation.
The overly rich situation could lead to oil contamination by the unburned fuel and resulting in washing off the necessary oil film on the cylinder bore increasing the likelihood of the piston rings and piston wearing out a lot faster.
The Rapid Bike units adjust the fuel injected by sensing the O2 readings and adjust these accordingly so in the open-loop the Rapid Bike units have hardly a thing to do.
To maintain the oil film on your cylinder bore it is also important that you use the correct grade (not too thin) oil and to keep the oil 'good' (fuel contamination always happens, it is the amount that counts, less than 2%) refresh oil and oil filter at least every 5,000 km.
 
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