Engine Rattle Between 2500-3000 RPM

[chip0704]

2005 Triumph Sprint ST. All stock. Great bike. Owned it since new. Starting to notice a slight rattling noise between 2500-3000 RPM. Doesn't matter what geat I'm in, but it's more noticeable if in a higher gear and lumbering through. Once I hit 3000 RPM, it goes away.

Normal? Anyone else notice it?

[oldndumb]

Can't really tell, but are you saying that you lumber in a higher gear? If so, you should understand that these bikes do not like that. They are meant to be operated in the power band by being in the correct gear.

Do you hear the noise at idle, in neutral? If so, does pulling the clutch lever have any effect on the noise? Do you hear the noise at 2/3K while in neutral?

Have you considered something loose under the fairings as the noise source?

Bottom line, even though some members are going to tell you about noise sources on their bikes, it is very doubtful anyone is going to pinpoint your noise for you. You are going to have to do some work on your own and try to isolate it. The exhaust system and the radiator and oil cooler frames are a good places to start.

[dolson]

What grade fuel are you using? What's the OS temp.
We need more info.

[chip0704]

Thanks for the questions/suggestions. Providing more info:

Noise is more of a tinging sound, not loud, but I notice it because I'm like that.

Fuel type: 89 or 91 octane
Oil was changed in April, about 1000 miles ago.
Outside Temperature: 70-85 degrees F
At idle (whether in neutral or 1st gear): no noise
I've also heard the noise when accelerating in 2nd gear (between 2500-3000 RPM), so that seems to eliminate the higher gear observation. It's possible the noise is there at higher RPM and perhaps the natural sound of the engine drowns it out, not sure.

I agree I need to troubleshoot more. Seems to be more of an engine noise than a cosmetic rattle. But I'm no mechanic so I'll keep checking before my next service. I actually had my dealer check on this last summer, and they put it on the dyno and said there was no issue.

[DrTriumph]

If you can safely record the noise somehow, I am sure someone can more accurately point out what could be wrong. One thing that seems simple but may be causing it is the chain. If it is too tight or too loose it can make funny noises at certain RPM's. My old bike Honda VF100F 1984, made a funny noise at 3000rpm when the chain was too tight once, corrected the chain tension and fixed the problem.

Hope it is something simple like this.

Dr. T

[shockingelectrician]

I am no expert on Triumphs, I just purchased a '98 Sprint. While I was on my quest to purchase one I did run across a common problem, with an easy fix. It does seem like the noise you are describing could be this.
On many of the triples, it seem like the fan for the alternator come loose on the alternator shaft and makes a tinny rattle noise. The fix is as simple as removing the alternator cover, re-threading the bolt hole for the fan and installing a new bolt with lock washer and medium strength thread lock.

[Croak]

OnD is right, these engines are meant to operate higher in the RPM band, and most new riders and/or V-twin riders tend to run them too low in the RPM band. You should pretty much never see 2500-3000 RPM in any gear but 1st.

Lugging causes all kinds of problems, and one of them is a tendency for pinging, even with high octane fuel, which is my guess on what you're hearing.

[DTONA]

Originally Posted by Croak

OnD is right, these engines are meant to operate higher in the RPM band, and most new riders and/or V-twin riders tend to run them too low in the RPM band. You should pretty much never see 2500-3000 RPM in any gear but 1st.

Lugging causes all kinds of problems, and one of them is a tendency for pinging, even with high octane fuel, which is my guess on what you're hearing.

Firstly, OnD and Croak have hit the nail on the head. If your running at 2500rpm in higher gears you are labouring the motor. These bikes are happiest cruizing at 3500-4000rpm, maybe dropping down to 2750rpm on the straight and flat, but don't try and increase your speed from there, safer to drop back a gear or 2.

Second, I don't know about the 2005model, but in my manual for the 2009 model it advised to use no less than 95ron. if you are running regular unleaded you are damaging your motor. The science behind it is, the lower the ron the faster the fuel burns. 98ron will give you a longer burn per stroke, meaning less jolting to reduce 'pinging' and being that it is buring longer there is greater expansion meaning greater power, and also being that it is burning longer it is burning off more of the carbon, which means less carbon build up in your motor. It doesn't matter so much in the older 955 sprint motors as they had a lower compression ratio than the 1050 which means carbon build up is not a problem and with the engine not being as tight there is less resistance onthe stroke meaning it is less likely to ping.
for the sake of an extra $1 per tank of fuel, run 98 octane. Your motor will run cleaner, smoother and last longer, and for the sake of trying to save a negligable amount of fuel on your journeys, run at a higher rpm to avoid labouring the motor. If you've been running 91octane for a while, you may not notice the difference for a few tanks of fuel.

[chip0704]

Ok, I did some more observing of my machine tonight. I usually ride with a full face helmet and didn't notice this before:

The pinging noise DOES occur at idle, and in neutral. It seems to be more evident in the 2500-3000 RPM range, and after that is harder to hear mainly due to wind noise. But the slight pinging noise is always there.

I have a short city commute to work, so I find myself around the 3K RPM range a lot unfortunately. I guess I'm doing something wrong if you're saying I shouldn't be. I have also rolled on the throttle in higher gears from lower speeds to see what type of response I would get and know how it would perform.

Regarding fuel, my manual simply says 89 octane or higher (US ratings). Our highest octane is 93. I can increase it, no problem.

[DaveM]

Originally Posted by chip0704

Ok, I did some more observing of my machine tonight. I usually ride with a full face helmet and didn't notice this before:

The pinging noise DOES occur at idle, and in neutral. It seems to be more evident in the 2500-3000 RPM range, and after that is harder to hear mainly due to wind noise. But the slight pinging noise is always there.

I have a short city commute to work, so I find myself around the 3K RPM range a lot unfortunately. I guess I'm doing something wrong if you're saying I shouldn't be. I have also rolled on the throttle in higher gears from lower speeds to see what type of response I would get and know how it would perform.

Regarding fuel, my manual simply says 89 octane or higher (US ratings). Our highest octane is 93. I can increase it, no problem.

That is basically idling and ok for a big Vee twin but not a Triple.

DaveM