Jump to content
Sign in to follow this  

Crank balancer knock

Recommended Posts

Since I've had this bike I hear a clunk upon accel, and when I did the loctite fixes I noticed a small play between the counterbalancer gear and the primary gear that drives it. Upon rotating the engine by hand I'd hear something very similar to that clunk when the counterweight went past the top and fell back. The pin is fine, it's really one gear clunking against another.

 

 

rmsp.jpg

 

 

So I'm thinking maybe it's those springs that are making this clunking stronger , what if I swapped the gear for an E model gear, that doesn't have any springs (parts nº 3 below) ??

 

10.gif

 

 

 

 

 

10.gif

Share this post


Link to post
Share on other sites

Unless the spring items are bad, there is no noticeable difference betwen the two (I've run both)

 

I assume your primary drive parts all look good too, that there is no discernable bearing play, that your clutch hub (a comon 'noisy' part) is also good?

Share this post


Link to post
Share on other sites

Unless the spring items are bad, there is no noticeable difference betwen the two (I've run both)

 

I assume your primary drive parts all look good too, that there is no discernable bearing play, that your clutch hub (a comon 'noisy' part) is also good?

 

I've been through all this quite recently doing the loctite fixes, and everything is tight and looks brand new (as it should, the bike has only 2500 mi on it).

 

Why would you have tried both gear types, was it because of this noise too ?

Share this post


Link to post
Share on other sites

No. I tried both gear types because I had them 'in stock'.

 

Brand new bike,.... I suspect you are hearing piston slap due to too low an idle. It should be above 1,800 rpm. A quick grab of the throttle at low rpm will make (and be) nasty.

Share this post


Link to post
Share on other sites

No. I tried both gear types because I had them 'in stock'.

 

Brand new bike,.... I suspect you are hearing piston slap due to too low an idle. It should be above 1,800 rpm. A quick grab of the throttle at low rpm will make (and be) nasty.

I'll try that, thanks.

 

Still, it seems intuitive that the if the CTB is spring-mounted, said springs will release their tension once the weight goes past its TDC and clunk the gears against one another all the stronger. Especially under acceleration. This clunk can be heard quite clearly, and it really sounds like the noise that bothers me when I ride, here's a video:

 

                http://youtu.be/MDkxvlwKkjc

Share this post


Link to post
Share on other sites

You are over analyzing, a big problem people have. The crank/counterbalancer spin pretty fast, even at idle. All the springs so is ever so slightly smooth the vibrations.

 

Make a new video, with the nut on.

 

 

What rpm is your idle set to?

Share this post


Link to post
Share on other sites

You are over analyzing, a big problem people have. The crank/counterbalancer spin pretty fast, even at idle. All the springs so is ever so slightly smooth the vibrations.

 

Make a new video, with the nut on.

 

 

What rpm is your idle set to?

 

Yes, I know, everybody tells me that. But I want things to be perfect, at least in the realm of mechanics.

 

Here's a video with the nut on, and another of the bike running, since I've no way of measuring the RPM.

 

http://youtu.be/efmcmsJAd4U

 

https://www.youtube.com/watch?v=hbinHwiFeO4

Share this post


Link to post
Share on other sites

Of the two videos, the first is set to 'private' and it cannot be seen.

The second, the bike sounds as normal as a poor recording can sound normal. Though RPM sounds about right.

Share this post


Link to post
Share on other sites

Of the two videos, the first is set to 'private' and it cannot be seen.

The second, the bike sounds as normal as a poor recording can sound normal. Though RPM sounds about right.

Sorry, fixed.

 

Well so piston slap it shouldn't be, that's a relief.

 

It sounds normal because the noise only comes up when riding. It's nothing really alarming or anything, not a clank or a rattle, it's just as if a small hammer were loose and tapping to the motor vibration. I already removed the decomp, but that didn't change anything. Engine runs great, lots of power. A mechanic told me that's their normal noise. I guess I'll try swapping the gears anyway when the next oil change comes around.

Share this post


Link to post
Share on other sites

Yup!  That is the EXACT knock that has been driving me crazy for the last month.  Mine is an '08SM with 2K on it that has been sitting for 4 years.  I've got it all sorted and done all checks and fixes, yet it sounds just like a rod knocking.  With about 600mi of thrashing and knocking with no metal showing up in the oil, I've just decided that the noise is just the nature of the beast and I'm gonna keep flogging! 

 

Please keep us posted as to whether the gear change eliminates the knock.  I too prefer for a perfectly running engine to sing, not knock!  :o)

 

Later,

David

Share this post


Link to post
Share on other sites

Mine used to make a similar sound , it hated to be lugged and I had to down change all of the time so I didnt get the noise if I want to accelerate . Bought a CW big bore , that fixed it ! greg

Share this post


Link to post
Share on other sites

Oh, believe me.....mine's not knocking because it is being lugged!  My other bike is a KTM SuperDuke and when I get on the poor little DRZ, it gets flogged unmercifully just to keep things entertaining!  ;o)

 

If/when it ever grenades, I will probably won't go the stroker route, but will most likely do the big bore/cams upgrade. 

Share this post


Link to post
Share on other sites

Well, interestingly enough, when I was doing the loctite fixes, a sharp-eyed member noticed, on a picture I had posted, that there was a one tooth offset on the gears that should have their markings aligned :

 

qekz.jpg

 

I was able to find one reference to a similar setup, also on an S . For some reason, it may be that the spring-mounted version of the CB gear is factory assembled that way. It's strange however, that it's one notch late rather than early (rotates ccw), as one would expect because of the spring compression. At the time I thought it was a mistake and corrected it :

 

u8ue.jpg

 

But that didn't make any difference as to the clunking/tapping noise. Still it would seem Suzuki was trying to compensate for something by assembling that way.

 

Anyway, I guess it's better to have a single part instead of six, especially when you have noise problems. I'll order the gear, nut and washer tomorrow, and will post back when things are ready.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×