Injector making a racket

[pwillikers]

There's a serious clackety noise coming, I'm pretty sure, from the left injector. At idle it's quiet but if I just crack the throttle, off idle it takes to a clacketing. It quiets back down around 3k RPM and above and it runs just fine. Please listen to the Injector Noise and weigh in with your experience. Is this an injector about to fail or something else? Should it be replaced?

[wswartzwel]

Have you checked the throttle shafts for wear?

[pwillikers]

Thanks Swart, no I didn't check. There's only one page, p. 126, in the manual concerning the "throttle valve stub pipe" and there's no mention of checking the throttle shafts for wear. Only that the "Throttle stub pipe intl. dia." should be 45mm. So, you're suggesting I remove the "throttle valve stub pipe" and check the throttle plate shaft for excessive play in the pivot in the body - enough to rattle and clack about?

[pwillikers]

Duh Swartster,

If I put my finger on the throttle shaft, the noise goes away. Is it likely the shaft or the TB that's worn? Do I need to replace the entire TB or can just the shaft be replaced? The parts aren't listed separately.

[Moybin]

Probably a bit of both for wear (shaft & body). I've wondered if a bushing could be sweated into the body and the shafts coated. It would make more sense to use a sealed needle bearing to get the low resistance to rotating needed while maintaining a gas-tight seal.

[Moybin]

Another high-tech option would be to create a magnetic liquid seal, similar to those being used in high-end woofers & tweeters to dissipate heat off the voice coil. Gas-tight and totally free to rotate. Might require a non-ferro magnetic shaft (not carbon steel or 400 stainless).

[signit98]

...with the heat cycling, the static and inductive energy, the friction involved and some other, minor (i.e. weather) influences, I am not sure of the feasibility, Moybin!?

[JonyRR]

there are various car places out there that replace TB bushings.
the BBparts site talks about both boring the TB's and replacing the shaft bushing. might check it out.

[wswartzwel]

The simplest option would be replacement.... With a R1200S.

Paul, while I am sure there are some shops around that could rebuild yours, I would just replace them, either low mileage used ones or new... $600 for the pair, and be done with it.

[Graeme P]

I went through a similar mind numbing exersize trying to find a rattle ,replacing everything that moved adjusted rocker clearance twice replaced cam chain tensioner ,adjusted rocker side movement etc.
Finally seconds before I smashed the heads off with an axe I touched the left side plug cover and found it was jumping up and down in time with the noise I pushed on the cover and the noise stopped .
On close examination the plug wasn't loose in the head but the ceramic was loose in the metal body ,when it warmed up it would get looser and jump in and out.
Reaclling when the noise started I had to stop rather quick in traffic then checking out the blond in the car beside me I neglected to change back to first susequently stalling in 2nd or 3rd gear ,sounds rediculouse but it must have over pressurised the plug and loosened the crimp on the ceramic isolator and click click click.
Good luck with yours.

[pwillikers]

To recap, My left side TB made a racket. Listen here. (The "tack, tack" you hear is from the throttle plate pivot shaft banging around inside it's pivot in the TB.) Does yours? With the engine running put your finger on the pulley for the throttle cable. Its on the inside of the TB between the TB and the engine. If the noise stops your throttle shaft is worn out.

My search yielded these alternatives for a fix:

• Buy a replacement from BMW - $300.
• BingCarburetor.com has a rebuild kit for $75. It's not listed on their website - call and ask for TS. Tell him you want the rebuild kit. You need the Bing part number which is stamped into the web on the bottom of the throttle body. My part number was: "BING 75/45/109"
• Beemerboneyard had a left side TB with position sensor available for $130.

I was in a hurry so I went the quick and easy Boneyard route. If I'd had the time, I would have gotten the rebuild kit from Bing and learned something new.

I replaced the TB, did the "zero=zero" setup and balanced the TBs. The clackety noise is significantly reduced but not quite gone. I wonder if the salvage TB is slightly worn? I recorded the noise of the salvage TB for comparison sake. Listen here..

Also, my bike has had a persistent roughness or "stumble" at very small, steady throttle openings between 3K and 4K RPMs since I picked it up - 50K miles ago. I initially thought it was the fabled BMW twin "surging" and became very familiar with IBMWR.org, my TwinMax and a box fan - balancing the TBs in repeated, unsuccessful attempts to eliminate it.

About 20K miles ago, when I installed a shorter torque arm and Ohlins, I did experience "surging", a "rum, rum. rum" in fourth gear in the 3-4k rev range, which I also was never able to TB balance away. It progressively went away on it's own. I think it might have been due to a realignment of the drive shaft u joints caused by the longer shocks and a shorter torque arm. I was never able to really tell for sure. And it's gone now.

Anyway, the really good news is that the stumble is now significantly improved with the better, salvage TB. It's still there but much less noticeable. I can't help wonder if I'd rebuilt the TB instead of installing the salvage one if the throttle roughness would have been eliminated altogether.

[Bigred455]

Paul ARGG! Just went and test rode the bike after the fuel system repairs and I have distinct Clackety clack noise coming from the RH bank. I remembered your post here so I reached down and pushed up on the throttle body shaft, noise gone haha. I'll grab one of my spares for the mean time, but definitely am going to attempt a repair. I will have to dissassemble and to get a real idea of what will need to be done, thanks for the heads up though.