Not accelarating properly - Wrist Twisters
 
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post #1 of 15 Old 06-28-2015, 01:13 PM Thread Starter
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Not accelarating properly

Hey guys
Hope someone can give me some advice .
So here are the simptoms :
In sixth gear doesn't accelarates over 170-175km/h
It has k&n airfilter (clean) and an akrapovic exhaust end pipe .

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post #2 of 15 Old 06-28-2015, 02:16 PM
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This is only when in 6th gear? Will any other gears exceed 108mph/175kph?

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post #3 of 15 Old 06-28-2015, 10:18 PM Thread Starter
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In 5th it goes faster but not whit much . It feels like it runs out of hp.

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post #4 of 15 Old 06-28-2015, 11:24 PM
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Quote:
Originally Posted by Lucian View Post
In 5th it goes faster but not whit much . It feels like it runs out of hp.
What sprocket ratios are you running?

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post #5 of 15 Old 06-28-2015, 11:32 PM Thread Starter
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The gearing is factory setting. Today im taking out the k&n and cleaning it maybe thats the awnser.

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post #6 of 15 Old 06-29-2015, 11:06 AM
just send it.
 
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170 KPH is about 105 MPH... I don't think the 9er has much more oomph to go any faster. Remember, this is a naked bike and you don't have aerodynamics working in your favor at those speeds.



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post #7 of 15 Old 06-29-2015, 11:27 AM
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Quote:
Originally Posted by crakerjac View Post
170 KPH is about 105 MPH... I don't think the 9er has much more oomph to go any faster. Remember, this is a naked bike and you don't have aerodynamics working in your favor at those speeds.
With 17/44 gearing I can very easily get to 120 mph, from there it will slowly get to to 137 mph if given the room. 105 is low and something is amis.

What rpms are you shifting at as you go through the gears? It's possible you might be shifting to low.

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post #8 of 15 Old 06-29-2015, 01:36 PM
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Quote:
Originally Posted by crakerjac View Post
170 KPH is about 105 MPH... I don't think the 9er has much more oomph to go any faster. Remember, this is a naked bike and you don't have aerodynamics working in your favor at those speeds.
Seriously?? I'm certain I've had mine up to at least 125 if not 130. Claimed top speed is 142. 105 is dog slow compared to what it should be capable of pulling. Sure, aero sucks on a naked, but the motor still pulls like a tractor. It just gets more uncomfortable as you increase speed above 80mph.

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post #9 of 15 Old 06-29-2015, 01:41 PM
just send it.
 
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Maybe I just remember things poorly, but I thought the 9er would go like a bat out of hell up until about 110, then just slowly climb upwards until you ran out of road.



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post #10 of 15 Old 06-29-2015, 02:13 PM
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Unless there are other running complaints there are only a limited number of causes for the loss of power at the speeds you are talking about. They are, in no particular order:

Weak ignition caused by both coils going bad, high tension wires / plug caps old and arcing, weak or intermittent signal from the ECU, or badly worn plugs. Any of these would cause other running problems.

Restricted exhaust. Unlikely with the system you are running.

Low fuel pressure / delivery during high demand running. This can be caused by a fuel pump on its last legs, a clogged pump inlet screen, a partially clogged fuel filter, or all of the injectors contaminated with old fuel varnish. Of all of these the most likely is the fuel screen or filter, both of which are in the tank.

Restricted air inlet. Either the filter (unlikely with the clean K&N), or the inlet flapper valve, there to decrease the inlet noise in order to pass noise level requirements. Of these I'd say the flapper valve is the most likely, and the easiest to address. Go here: https://www.wristtwisters.com/forums/...ion-12219.html for a more or less comprehensive description of the "flapper mod". If it's stuck closed by a malfunctioning solenoid valve it would definitely restrict air flow enough to cause the symptom you describe.

Just for grins I took my 919 out for a ride and ran it past 100 starting at about 60 or so in 6th. It took just over 3 seconds to blow by 100, and was obviously anxious to keep right on accelerating. At that speed the motor is as smooth as a turbine. A while back I laid down on the tank and let 'er rip -- it showed signs of running out of breath at a calculated 134.6 MPH, but up to that point it was quite anxious to keep on accelerating. It's definitely no slouch.

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post #11 of 15 Old 06-29-2015, 05:32 PM
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Since Rob has chimed it, and it's my favorite answer, any chance its the FPR but only showing its head at high speeds?

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post #12 of 15 Old 06-29-2015, 05:44 PM
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Quote:
Originally Posted by crakerjac View Post
Maybe I just remember things poorly, but I thought the 9er would go like a bat out of hell up until about 110, then just slowly climb upwards until you ran out of road.
pretty much my experience. 110-120 comes pretty quick.... the 120 to 130.5 mph gps certified that i have done took so long it seemed. But she wanted to continue..... but i pansied out and have never been that fast since.

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post #13 of 15 Old 06-29-2015, 10:04 PM
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What about battery connections/ground wire? Would they drop top end speed or would you be able to feel that all around the Rpms?

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post #14 of 15 Old 06-29-2015, 10:11 PM
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Quote:
Originally Posted by andrewebay1 View Post
What about battery connections/ground wire? Would they drop top end speed or would you be able to feel that all around the Rpms?
It wouldn't be limited to just 6th gear. I think Rob may be onto something with his comment about the possibility of the Flapper solenoid failing some how.

I did a quick test myself today on the freeway. Blew past 100 mph from 60 in 6th very rapidly, and passed 120 which took a little longer but but did it with ease before I let off. During the track days, I recall that once past 120, the bike would take noticeably longer to get to 130 and then after that it was just a matter of needing the legroom to get past 135. I topped out at around 137-138 before running out of pavement and there was just not much left there, if anything. I'm not sure if it would actually break 140 given enough room. But 105-108 should be achieved with COMPLETE EASE.

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post #15 of 15 Old 06-30-2015, 04:44 PM
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With the stock setup I found it pretty easy to reach 130mph in no time, it took a bit longer to get up to 140. I've ridden full throttle on the interstate at 140 for miles, going faster on small hills. I'm also 300lbs at 5'11". If anyone can't get this bike to 130 within two miles, I'd say there was a problem. Just my .02.

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