Hey there, second post, first problem! Hope my english ist decent enough to explain.

My Nightster startet to rattle the other day, 8.000 miles run so far...it rattles slightly but inconsistant while smooth rinding, and rattles the most while full throttle, just for 2-3 seconds, and then it's gone but it will come back again and again.

it started to rattle after customization: new bars, speedometer relocation, relocation of the LED turnsignals to the fork and a new sissybar with custom licence plate holder

but maybe it's the engine? I just can't find the problem. The HD dealer i consulted is not sure about it, opended the engine, checked the exhaust but couldn't find anything and says he DOES NOT KNOW why the bike is ratlling!! wtf?

so here is a video I made:


skip to 0:30 if u want

I really appreciate your help!

thx David

 

StreetReaper:

Sounds like a loose primary chain.....it seems to get louder when the camera is closer to the left side of the bike.It's an easy adjustment,about a 20 minute job.

Glock Man

 

If your referring to the metallic rattle when you whack the throttle open, it sounds like "pinging" to me. Primary causes are, octane too low, A/F mixture too lean or timing too far advanced. Are you running Premium grade fuel? Without a good tuner module you can't do much with the A/F ratio or timing.

 

thanks for the answers so far. it's definitely not the primary chain and not the fuel since i run premium and both potential causes are checked and found not to be the cause. :-(

 

What are you referring to here, the primary chain and fuel or the timing and A/F ratio? If you're saying the dealer checked the timing and A/F ratio, there's not much for them to check and adjust with the stock ECM, you need a programmable tuner for that.

Ignoring a "pinging" problem is a bad idea, it often leads to a hole in a piston.

 

it's clear when u ride it that it's not pinging, it would just cause another noise, that's also what the mechanics at HD say. and it has the stock ECM, i always used the same premium fuel which was perfect for thousands of miles and now it appeared all of a sudden after about 8.000 miles on the clock....

 

Well here's some thoughts,

It sure acts like pinging...open to full throttle noise appears then disappears.
Yet you've ruled that out..OK.

Does the noise occur with a smooth roll on to full throttle or only when the throttle is "whacked" open?

Next does it occur only in/ at a certain RPM (or miles per hour in a certain gear) range?


Easy inspections...primary chain, sprocket bolts/ belt, other critical fasteners, clutch adjustment, throttle body butterfly operation and mounting bolts, compression/ leak down test. Not as easy inspect valve train.

One notorious area of Sportsters is the clutch and clutch basket.
I think that might be the first area to inspect.
Drain the trans oil, remove the derby have a look.

Good luck.

 

I vote this.

 

thanks for your comment! the noise appears more silent and hard to hear while smooth riding and appears the loudest when the throttle is whacked open, but I have the Impression that the frequency of the noise increases more and faster than the RPM.
you can see in the video that RPM is low and starts to get higher when the throttle is whacked open but the noise frequency starts to increase faster and disapears when RPM gets higher....

 

Fuel tank mounting bolts loose?

John