General topics » Loud knock on startup?

Has anyone experienced a loud knock upon attempting to start their bike? It has happened three times in the last 10 months. I go to start the bike and there is a noticeable loud knock, almost like there’s no oil in the engine but I know there is. I release the starter button, what a few seconds and it starts like normal.

It should be noted that I had minimal (like the tiniest amount) of metal shavings on my oil plug when I changed it last month.

Should I just wait longer when I stand it up off the side stand? Or should I be more concerned than I currently am.

It happened a couple times on my wife's K1300S and I had the cam chain tensioner replaced.
It was a cheap fix for a scary noise.

The R1200RS also has a cam chain tensioner.

Zitat von Lee im Beitrag #3

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It happened a couple times on my wife's K1300S and I had the cam chain tensioner replaced.
It was a cheap fix for a scary noise.

The R1200RS also has a cam chain tensioner.

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Zitat von Doc4216 im Beitrag #4

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Thank Lee. I am going to have the dealer do my 12k maintenance and after that I will take over. I will have them check it.

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My recollection is that this was an issue with some oil head boxers. It was said to be the result of the time that it took for the hydraulic cam chain tensioner to fill with oil. Until it did, there was sometimes a loud knock. However, I have not heard that noise on my RS, but I did hear it occasionally on my R1150 and R1200 oil-head models.

Zitat von Lee im Beitrag #5

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Zitat von Doc4216 im Beitrag #4

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Thank Lee. I am going to have the dealer do my 12k maintenance and after that I will take over. I will have them check it.

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The forum did not let me edit before you replied.
On my wife's K1300S the noise continued for 5 to 1o seconds after starting.
Did yours sound normal after it started?

2 times my R1200RS gave a loud knock for a split second when starting then sounded normal while running.
I don't have a clue what caused it.

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Mines done that on cold start up from new. Dealer said it was the oil pressure buiilding in the camchain tensioners. Lasts less that two seconds just a know, a rattle and all good.

The move to HyVo chains (I think my memory is correct) on the 1250 has eliminated this.

I've never noticed this phenomenon. However, I'm admittedly oblivious to a great many things and rarely, if ever, use the side stand.

Zitat von Grumpy Goat im Beitrag #9

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Zitat von Lee im Beitrag #5

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Zitat von Doc4216 im Beitrag #4

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2 times my R1200RS gave a loud knock for a split second when starting then sounded normal while running.
I don't have a clue what caused it.

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In the 4 years I have owned my bike, I have experienced a loud "clack" (not "knock"; its a sharper sound on my bike) on first press of the starter button, and immediately after hearing that noise I have always released the button and not persisted starting the bike on that button-press. The second press of the starter button (a second after the first) resulted in a perfectly normal start, with no clacking or knocking after the bike started running.

So I have no idea of the persistence of the sound after / if the bike did start. This experience happened less than a handful of times in the 4 years. I always thought it might be some sort of "starter engagement" issue, not knowing exactly the gearing arrangement there. It so far has not caused enough concern for me to pursue a fix. Good to know that it may be related to the cam chain.

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I have experienced a loud "clack" (not "knock"; its a sharper sound on my bike) on first press of the starter button, I always thought it might be some sort of "starter engagement" issue

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If the cam chain tensioner is not holding pressure when the bike is off, the noise will continue for a few seconds after starting as pressure builds back up in the tensioner.

Thanks all, seems like others have experienced this "clack" or "knock" that I have.

I sometimes get a cough and a 'kickback' and a refusal to fire. It is loud but I wouldn't call it a knock. It's only happened very rarely and it may be because I've been too quick to release the starter button.

Zitat von Sanemancured im Beitrag #14

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I sometimes get a cough and a 'kickback' and a refusal to fire. It is loud but I wouldn't call it a knock. It's only happened very rarely and it may be because I've been too quick to release the starter button.

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