Porpoise during 1st gear acceleration - Stromtrooper Forum : Suzuki V-Strom Motorcycle Forums
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post #1 of 17 Old 08-27-2013, 07:22 PM Thread Starter
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Porpoise during 1st gear acceleration

I have a 2012 DL650 with 7500 miles, and wanted to run this by you guys in the general forum, since it may be something to do with chain-driven bikes in general.

Under hard acceleration (WOT) in first gear, I am noticing a slight porpoise with a frequency of about 4 per second. My first thought is that perhaps I am feeling a tight spot in the chain. Lube doesn't appear to affect anything. Any ideas?
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post #2 of 17 Old 08-27-2013, 08:04 PM
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No help

lift the rear end and spin the rear wheel and see if there are stiff spots
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post #3 of 17 Old 08-27-2013, 08:44 PM
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Quote:
Originally Posted by Kelly2012 View Post
I am noticing a slight porpoise
You can tune a fish, but you can't tunafish........

Why are you holding your bike in first gear for seconds on end, anyway?

Perhaps a picture of Lux Interior, of The Cramps, might help.........

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Last edited by jokermtb; 08-27-2013 at 08:48 PM.
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post #4 of 17 Old 08-27-2013, 09:48 PM
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post #5 of 17 Old 08-27-2013, 10:01 PM Thread Starter
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Tough crowd. Maybe it's second gear- since I'm not a squid I don't do it very much :-).


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post #6 of 17 Old 08-28-2013, 04:31 AM
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Not gonna make jokes. This is a new one on me but I'll throw out what comes to mind. Like Richw mentioned, check for tight spots in the chain as a first step. If you have a center stand, put the bike on it and spin the wheel and look for chain kinking or wheel wobbling. On second thought after re-reading your post, are you saying that the front or rear of the bike porpoises? From my experience, the term 'porpoising' refers to a boat's trim being too high which pushes down on the rear of the boat causing it to bounce up and down at the front under full throttle causing the operator to cut the throttle. I'm assuming that the rear of the bike is 'porpoising'. If that's the case, and eliminating the chain kinking, I'd have to consider an unbalanced tire next. Perhaps a weight came off. I'm making a stab in the dark here as I don't really know what the bike feels like.

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post #7 of 17 Old 08-28-2013, 09:27 AM
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Let me ask a question, using a scenario, to see if we can get some clarrification.

If I'm in traffic, and I'm just allowing Idle to pull me along in 1st gear (just letting go of clutch, no throttle) the bike will tend to be very jerky. I'd say about every 2 seconds or so. It kinda feels like it syncronizes with the sounds coming from the engine, but i'm unsure.

Is this what you are talking about? If not, would anyone like to enlighten me on why this.

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post #8 of 17 Old 08-28-2013, 11:49 AM Thread Starter
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Quote:
Originally Posted by lordneeko View Post
Let me ask a question, using a scenario, to see if we can get some clarrification.

If I'm in traffic, and I'm just allowing Idle to pull me along in 1st gear (just letting go of clutch, no throttle) the bike will tend to be very jerky. I'd say about every 2 seconds or so. It kinda feels like it syncronizes with the sounds coming from the engine, but i'm unsure.

Is this what you are talking about? If not, would anyone like to enlighten me on why this.
To clarify, and to provide more fodder, it's more of a twerk. There are many videos on youtube if you would like to see an example of the frequency of my bikes twerk. As an aside, I am performing a study on mass vs. twerking frequency in Hertz. My current problem is that the observer impacts the excitation frequency.

It only happens for about a second, and twerks about 3-4 times. I feel it in the front end. I do know my chain has a tight section, but I thought all chains did to a certain extent.
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post #9 of 17 Old 08-28-2013, 11:58 AM
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Is it possible you are bouncing off the rev limiter?

Pat- 2007 DL650A was ridden to all 48 contiguous states. I didn't quite make it to 17,000 miles on the 2012 DL650A.
Nicknames I use to lessen typing, Vee = 2002-2012 DL1000s. Vee2=2014-2016 DL1000s. Wee = 2004-2011 DL650s. Glee = 2012-2016 DL650s
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post #10 of 17 Old 08-28-2013, 12:11 PM
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mass vs. twerking frequency in Hertz

Holly molly, I've ridden my Vee lots and I don't even understand this question. But I'm curious so I'll ask my friend Mr Google and search up "twerks" on youtube.

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