LOUD start up clunk/knock noise

[legiteuphoria]

Hey guys I have 09 xb12r. Sometimes when I start up my bike I have to hold down the starter button, the bike will turn over once, pause, and then begin to turn over again and start. Sometimes instead of pausing it will turn over and a huge knock/clunk noise is made, it sounds terrible, It generally only happens once the bike is hot, like if I go out to get gas and then start the bike up again. Has anyone had this problem and figured out what it is?
I was wondering if it might have something to do with the battery/electrical when starting the bike since there is more resistance in the wires when the bike has been running already, if so does anyone know if the EBR buell battery would fix this, I was unsure whether they put out a higher amount of juice over the stock battery.

 

[2hy2ride]

How many volt @ the battery? How often do u ride? What type of battery is it?(Agm, sealed acid, lead acid, full gel, lithium)

 

[freak2180]

The pause at initial start up is common with these bikes. It's caused when you kill the bike the piston stops just before TDC. When you try to start the bike the starter has to overcome the cyl pressure before it can spin the motor fast enough to start.

The knock you here I'm not sure about but I'm curious to here the outcome.

 

[legiteuphoria]

I will check tomorrow and see what type of battery it is. The battery has never been changed though so it is the stock battery for the 2009 XB12R.
I bought the bike about 3 months ago and just started riding it this month, so far I've put 900 miles on it in 3 weeks so I'm riding it quite a bit.

The pause at initial start up is common with these bikes.   It's caused when you kill the bike the piston stops just before TDC.   When you try to start the bike the starter has to overcome the cyl pressure before it can spin the motor fast enough to start.   

This makes absolute perfect sense, thank you for describing in detail! As far as the knocking we shall see.

 

[twoguns]

i have the same sometimes. and i htink the knock is movement in the gearbox. i notice it most when i have rolled the bike in idle before turning off. next i start it i most likely get hte clunk.

 

[qhrjsdl]

Im using agm battery since 2009. Still working awesome...

 

[user_deleted]

The pause at initial start up is common with these bikes. It's caused when you kill the bike the piston stops just before TDC.

yes sir. it is called "compression bump" and i've described it many times on here. it happens randomly and perhaps 50% or higher during initial start-up. sometimes you will get a brief clunk but nothing indicating any type of engine or starter problem.

 

[redsfannz]

I had, and still get occasionally that clunk noise. A while back I had an issue where the starter pinion gear dropped down onto the starter motor (I think). Stopped the engine turning over. Im wondering whether its come loose again and is causing the crunch noise, again.

 

[Lrick1]

Thread revival!

I'm wondering if this has been fixed, I get the same banging noise once in a while, but only when the bike is hot (most of the time when I stop for gas). I don't think it's an electrical problem, but that noise scares the crap out of me every time, it sounds like the engine is chewing its own pistons!

 

[Danny522]

Mine did this the other day also. I started the bike then shut it right off because I forgot to put something under the passenger seat. When I restarted it made a loud clunk, scared me alittle bit. Like someone said I thought it sounded like the gear box. Only did it that one time.

 

[BambamXB12r]

I know this is an old thread but has anyone successfully diagnosed the grinding noise on startup? Mine just started to do it and am curios if there is anything I can do. Just like everyone says, only when it's hot and only once. Starts up next push just fine or I can just keep holding it and it will start. Any solutions yet?

 

[rchuff]

Make sure your engine light goes out before you start your bike this might help.

 

[BambamXB12r]

I always do that and it still does it every now and then.

 

[user_deleted]

check for proper room temperature adjustment of your primary drive chain....then live with the occasional "clunk". it's an H-D driveline thing. virtually all big-twins occasionally do it and tons of sportsters as well. why is anyone's guess.

 

[UMDterp13]

Mine does this too... No clue why. Some of my 08+ do it, some don't. until a rod comes through the case or my trans blows apart I don't worry about noises with Buells