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littledog · March 11th, 2010, 06:26 PM

I think my motorcycle has the odd tachometer behavior described above.

I got it on black Friday the day after Thanksgiving. The weather here has been consistently cold, until this past Tuesday I had not ridden in over 60 deg weather. I've got bunch of really warm clothes.

Due to the silly Kawasaki break in routine I know the speedometer shows 35 mph in 6th gear when the tachometer shows 4k rpm, and at 5k rpm in 6th gear, it shows 45mph. I could not stand the break in speeds, so I observed early on that I got 55mph at 6k rpm in 6th gear.

Very consistently, rpm x 9 / 1000 = mph in 6th gear.

That is until this past nice warm Tuesday afternoon, where I was going a touch over 30 mph at 4k rpm, and about 55 mph at 7k rpm. Even the idle looked to be a bit higher, but sounded no different than before. I drove the bike about 60mi while it was showing these unexpected gauge readings.

That night, at about 50 deg, I took the bike for a spin around the block, 20 mi or so. Back to the rock solid rpm x 9 / 1000 mph in 6th gear.

Today it was nice and warm again. I rode up to Martin Dam about 125 mi. round trip. For the entire ride, the tachometer - speedometer formula was about rpm x 8 / 1000 = mph in 6th gear.

What else to observe? Sound. My Ninja, when cruising in 6th at a certain speed, a new sound appears. I will call it "air box resonance", I don't know if that is an accurate term, but it always started at 6k rpm and 55mph before.

When the tachometer was "off" it started at 55mph and 7k rpm.

Air box resonance sound starts at 55mph in 6th gear, whatever the tachometer shows.

Another thing I have paid attention to is the fuel mileage. I know I am sort of ridiculous about numbers. However... if you're driving habits are consistent but your mileage goes down, there is a problem developing.

Driving back and forth to work I average 61 mpg. Driving the 45 - 55 mph back roads I get about 65mpg.

I used over half of the current tank full while the tachometer was "off", all of the current tank full used for fun riding on back roads. I just now filled it and measured 67mpg.

So,my Ninja is showing one of the tachometer symptoms, and it appears to me to be a fault with the tachometer reading only, with no loss of performance (inferred from fuel efficiency).

March 11th, 2010, 06:26 PM	#193
littledog ninjette.org member Name: Peter Location: Deep South, USA Join Date: Dec 2009 Motorcycle(s): 2009 Special Edition Ninja 250 a good memory, 2011 Suzuki DL 650 the new ride Posts: 131	I think my motorcycle has the odd tachometer behavior described above. I got it on black Friday the day after Thanksgiving. The weather here has been consistently cold, until this past Tuesday I had not ridden in over 60 deg weather. I've got bunch of really warm clothes. Due to the silly Kawasaki break in routine I know the speedometer shows 35 mph in 6th gear when the tachometer shows 4k rpm, and at 5k rpm in 6th gear, it shows 45mph. I could not stand the break in speeds, so I observed early on that I got 55mph at 6k rpm in 6th gear. Very consistently, rpm x 9 / 1000 = mph in 6th gear. That is until this past nice warm Tuesday afternoon, where I was going a touch over 30 mph at 4k rpm, and about 55 mph at 7k rpm. Even the idle looked to be a bit higher, but sounded no different than before. I drove the bike about 60mi while it was showing these unexpected gauge readings. That night, at about 50 deg, I took the bike for a spin around the block, 20 mi or so. Back to the rock solid rpm x 9 / 1000 mph in 6th gear. Today it was nice and warm again. I rode up to Martin Dam about 125 mi. round trip. For the entire ride, the tachometer - speedometer formula was about rpm x 8 / 1000 = mph in 6th gear. What else to observe? Sound. My Ninja, when cruising in 6th at a certain speed, a new sound appears. I will call it "air box resonance", I don't know if that is an accurate term, but it always started at 6k rpm and 55mph before. When the tachometer was "off" it started at 55mph and 7k rpm. Air box resonance sound starts at 55mph in 6th gear, whatever the tachometer shows. Another thing I have paid attention to is the fuel mileage. I know I am sort of ridiculous about numbers. However... if you're driving habits are consistent but your mileage goes down, there is a problem developing. Driving back and forth to work I average 61 mpg. Driving the 45 - 55 mph back roads I get about 65mpg. I used over half of the current tank full while the tachometer was "off", all of the current tank full used for fun riding on back roads. I just now filled it and measured 67mpg. So,my Ninja is showing one of the tachometer symptoms, and it appears to me to be a fault with the tachometer reading only, with no loss of performance (inferred from fuel efficiency).