Crazy Tach + Sputtering

TennsDog · May 4th, 2017, 11:39 AM

My motorcycle's been having a strange behaviour basically since starting it up this spring. The two main symptoms I'm seeing are 1) the tachometer going all crazy and bouncing around between the real value and 5k above and 2) the engine sputtering as though it's not getting gas.

When the tach bounces around, there's no real change in feel of the motorcycle, so it doesn't really seem like the engine is actually doing that, but it's going so fast up and down I don't know if it's even possible for the engine to do that or if I'd notice if it could. When I went to take it out recently, it was doing that immediately on start-up, and I noticed that the lights (headlight and dash) were flickering a lot too. I decided I lacked confidence in it to get me to and from safely, so I opted for the car.

I originally thought it might be something wrong with the fuel line and it actually was not getting gas and then getting too much or whatever, but with the lights flickering, that seems to indicate something electrical. I did have my battery on a tender all winter, so I'd think it should be fine. And I had the carburetors rebuilt about 4k miles ago.

Anyone have any ideas what this could be?

Triple Jim · May 4th, 2017, 11:44 AM

It appears to be an electrical problem. I'd start by measuring battery voltage with the engine off and with it running at various speeds to see what's going on. You could have a loose connection or a bad regulator, among other things.

jkv45 · May 4th, 2017, 01:28 PM

^ As TJ said - check the battery voltage and connections.

TennsDog · May 16th, 2017, 02:30 PM

Thanks for the replies. Turns out the battery cables were terribly loose. My best guess as to what happened was that I didn't get the cables tight enough after reinstalling the battery from storage, and my first ride loosened 'em right up so that they were making a really bad connection, and even just the vibration from the engine while still was enough to cause issues.

I got them all tightened up and have had no issues on several rides since.

May 4th, 2017, 11:39 AM	#1
TennsDog ninjette.org member Name: Damon Location: WI Join Date: Aug 2015 Motorcycle(s): 2006 Ninja 250 Posts: 19	Crazy Tach + Sputtering My motorcycle's been having a strange behaviour basically since starting it up this spring. The two main symptoms I'm seeing are 1) the tachometer going all crazy and bouncing around between the real value and 5k above and 2) the engine sputtering as though it's not getting gas. When the tach bounces around, there's no real change in feel of the motorcycle, so it doesn't really seem like the engine is actually doing that, but it's going so fast up and down I don't know if it's even possible for the engine to do that or if I'd notice if it could. When I went to take it out recently, it was doing that immediately on start-up, and I noticed that the lights (headlight and dash) were flickering a lot too. I decided I lacked confidence in it to get me to and from safely, so I opted for the car. I originally thought it might be something wrong with the fuel line and it actually was not getting gas and then getting too much or whatever, but with the lights flickering, that seems to indicate something electrical. I did have my battery on a tender all winter, so I'd think it should be fine. And I had the carburetors rebuilt about 4k miles ago. Anyone have any ideas what this could be? Last futzed with by TennsDog; May 4th, 2017 at 11:43 AM. Reason: Fixed typo

May 4th, 2017, 11:44 AM	#2
Triple Jim Guy Who Enjoys Riding Name: Jim Location: North Carolina Join Date: Jul 2016 Motorcycle(s): Ninja 250 Posts: A lot. MOTM - Oct '18, Aug '17, Aug '16	It appears to be an electrical problem. I'd start by measuring battery voltage with the engine off and with it running at various speeds to see what's going on. You could have a loose connection or a bad regulator, among other things.
	2 out of 2 members found this post helpful.

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May 4th, 2017, 01:28 PM	#3
jkv45 Rev Limiter Name: Jay Location: WI Join Date: Jul 2013 Motorcycle(s): '06 SV650n, '00 Derbi GPR, '64 CA77 Dream 305, '70 CL450 Scrambler, numerous dirt bikes Posts: A lot. MOTM - Jun '18, Oct '16	^ As TJ said - check the battery voltage and connections.

May 16th, 2017, 02:30 PM	#4
TennsDog ninjette.org member Name: Damon Location: WI Join Date: Aug 2015 Motorcycle(s): 2006 Ninja 250 Posts: 19	Thanks for the replies. Turns out the battery cables were terribly loose. My best guess as to what happened was that I didn't get the cables tight enough after reinstalling the battery from storage, and my first ride loosened 'em right up so that they were making a really bad connection, and even just the vibration from the engine while still was enough to cause issues. I got them all tightened up and have had no issues on several rides since.