Low end noise.. - Wrist Twisters
 
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post #1 of 14 Old 10-10-2007, 12:47 PM Thread Starter
 
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Low end noise..

Hello all,
I've had my '03 919 for about 4 months now and really do love it. My gixxer 750 was killing me in Atlanta traffic so I had to make a change.

As I'm getting used to this bike I've noticed a few things about it that kind of worry me.. first is the fscking front brakes howling at low speed, my god that noise just screams "Hey look at me and my POS Hoopty!". But the worst is a knocking noise that I hear at low rpm under heavy load. To me it sounds like an american V8 with hydraulic lifters that aren't pumped up with oil, like a quick rattling sound, but then it disappears at about 3000 or so. Everything else about the bike is smooth, easy, and comfortable, but I want to make sure this isn't some kind of internal engine issue that I need to look out for. Does anyone else's bike sound like this? Would mis-adjusted valves make this kind of noise, especially since it idles quietly and is quiet otherwise.

Thanks in advance

Shawn

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post #2 of 14 Old 10-10-2007, 01:15 PM
 
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Do these bikes have a Hydrolic cma chain tensioner ? My CBR 600 F2 sounded like it was coming apart when it stopped working really well. Replaced it and horrible noise was gone -

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post #3 of 14 Old 10-10-2007, 01:35 PM
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It's just the fuel injectors making noise. Nothing to worry about. Mine did it too.

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post #4 of 14 Old 10-10-2007, 02:21 PM
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Quote:
Originally Posted by hooker_47 View Post
It's just the fuel injectors making noise. Nothing to worry about. Mine did it too.
+1.

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post #5 of 14 Old 10-10-2007, 02:45 PM
 
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What grade fuel are you running?

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post #6 of 14 Old 10-10-2007, 03:30 PM
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Quote:
Originally Posted by HondaJim View Post
+1.
Air box / intake noise as well. All is normal.

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post #7 of 14 Old 10-10-2007, 07:21 PM Thread Starter
 
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Low end noise..

Thanks for the reassurance, I was hoping it was ok, but buying a used bike that you aren't familiar with can be dicey.
I had started off running premium, only out of habit because that's what the Gixxer needed, but have been running regular for the last couple of months and have had no issues.
I got the service manual today, so this weekend I'll dig into it a bit and check the valves and cam chain(s) and give myself some peace of mind.

I need to get some pictures up, but honestly it looks just like everyone elses asphalt black one right now, so there's no real reason.

Thanks for the replies.

Shawn

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post #8 of 14 Old 10-10-2007, 09:47 PM
 
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Mine makes a bit of noise under load as well. (bought with 0 miles) After a week or so and some reasuring posts from guys here, it has gotten so it doesnt worry me, but i still want to get rid of the noise. Not entirely sure how injectors work, but presumably the computer sends some variable amount of current, or pulses for a specific time to deliver a specific amount of fuel, and what we are hearing is when those injectors bottom out?


I'm only getting around 30MPG. I think that means it is runing verrry rich, so it is already close to maxing out the injectors... (?) anyway i've ordered a power commander hoping that will improve the mileage, and maybe reduce the noise as well? Is it easy to adjust that "accelerator pump" setting?

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post #9 of 14 Old 10-10-2007, 11:01 PM
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ZekesGarage:
And anyone else -- the camchain tensioner is an oil damped mechanical type consisting of a rotationally spring loaded cylindrical ramped collar with a series of detents cut in it bearing against the plunger at one end and a hardened steel pin at the other. As the camchain tension changes, especially at low RPM, the collar rotates back and forth slightly until it goes far enough to engage the next detent. If the collar rotates almost but not quite far enough to engage the next detent, it springs back to the previous one, resulting in a little noise from the chain which can sound like a knock. If it bothers you a cure may be affected by removing the tensioner and making a new gasket from slightly thicker material, which may allow the collar enough rotation to stop the noise. Having said that, keep in mind it's a Honda -- it can make the same noise for 100,000 miles without problems!
Spaceman spiff:
The solenoid type injectors are driven by a signal from the ECU of varying duration: the longer they are open, the more fuel delivered. One of the most important characteristics of any injector is a positive shut off -- the valve pintle "slams" shut because it is driven not only by a fairly stiff spring, but also by fuel pressure behind it. This is essential for two main reasons: first, it positively closes instead of bouncing, which prevents excess fuel from being injected; and the closing force helps keep the pintle face and seat clean. This slam causes the noise which is common to practically all injected motors, and is not a cause for concern: indeed, if you don't hear it there is a problem.
Either that, or setting your blaster to "medium rare" instead of "shake and bake" may decrease the noise (at least according to Hobbes).
As for your 30MPG: how do you normally ride it? If it spends a lot of time over 7,000 RPM, that may explain it. Otherwise, there is a problem such as a weak coil or spark plug insulator cracked which should be addressed before resorting to a PCIII: the point being if one cylinder is running rich leaning everything out may help that one, but will cause too lean in the other three, possibly causing problems down the road.

Rob

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post #10 of 14 Old 10-11-2007, 07:09 AM Thread Starter
 
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Detents and Pintles oh my!

Rob,
Thanks for the info on the chain tensioner, feeling even better about this machine now. I never heard the injectors on my gixxer, too much noise in the gearbox! I'll just ride the pee out of it and see what I get.

Shawn

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post #11 of 14 Old 10-11-2007, 09:37 AM
 
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Quote:
Originally Posted by ZekesGarage View Post
I had started off running premium, only out of habit because that's what the Gixxer needed, but have been running regular for the last couple of months and have had no issues.


Shawn
Did you notice the noise before you stopped using premium?

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post #12 of 14 Old 10-11-2007, 01:42 PM Thread Starter
 
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Tubby,
I can't recall when I started noticing the noise, but I did run a couple of tanks of 93 through it thinking it might be detonation, but it didn't help.

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post #13 of 14 Old 10-11-2007, 01:49 PM
 
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Well damn.

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post #14 of 14 Old 10-11-2007, 02:12 PM
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Don't worry about octane numbers, this beast will run on low test Mexican cactus juice!

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