low idle and clacking noises-maybe clutch/tranny

[Luca]

Hi everyone,

Today as I got home from work, I noticed that my 82R65LS was idling low  with the engine fully warmed up after the 20 mile ride(500-750... I have it set around 1000)

There was also a sort of clacking noise that sounded like a loose cam chain, but it quiets down with the clutch lever pulled.  I have recently lubed the transmission splines with honda moly 60... just a light coat applied with a toothbrush.  The transmission still appears square to the bell housing

Though I haven't yet checked the carbs, I fully serviced them not more than a month ago and they were perfectly balanced.  The plug wires are firmly in the coil, and plugs fully seated into the head.

I'm having scary thoughts about the $2000 dollar o-ring (3K if you wreck the crankshaft).

I have done some sustained speeds with the engine around 6K (fifth gear of course), but I can't imagine the bike couldnt handle that.  Once I get off idle, the engine quiets down and the shifting is always smooth.

Also, I just retorqued the motor mounts the other night to 45 ft-lb front and 40 ft-lb rear

I'd appreciate any advice on what to look for, or if these sound like the symptoms of a common problem.  I guess I'll be checking my oil filter in a few minutes.  Dont worry, I have a spare oring and 2 shims.

Thanks,
Luca

[Mike V]

Luca,

Have you drained your transmission fluid lately?  Had a close look at your magnetic transmission drain plug?

[Luca]

I did service the transmission when I put the bike on the road, about 1K miles/1 month ago.  There was one noticable fleck of metal on the plug, the rest was fuzz.  It does draw a little bit of oil up from the driveshaft, perhaps because I have no sealant on the bolt in the bottom of the airbox that goes to the transmission.

Though pulling the clutch quiets the noise, the idle still seems to stay low

[Luca]

Update:

There was some fine grit on the magnetic drain plug.  No signs of water in the oil.

Using a screwdriver as a stethoscope I got the loudest noise at the transmission housing

[Mike V]

Luca,

I think you may be dealing with two separate issues; idle speed and transmission noise.  

Does your idle speed stay constant when you engage and disengage the clutch while in neutral?  If you have some transmission bearings failing you can sometimes distinguish tell-tale noise by spinning and rocking your rear wheel back and forth with the transmission in neutral.  I can tell from first hand experience a transmission with bad bearings is noisy - especially when hot and in neutral, engaging and disengaging the clutch.  I would keep an eye on your transmission fluid and magnetic drain plug for continuing metal particles.  Unbalanced carbs can amplify the noise of a failing transmission because the engines combustion pulses are not in harmony.

Get a second opinion if you can if you have a knowledgeable source nearby.  These transmissions do make some noise when hot, even the healthy ones.  If your transmission is trying to tell you something it's best to get it looked at $$ooner than later.  You mentioned there's no signs of water in your gear oil or emulsification - hopefully that's a good thing.

Try doing a full carb balance and idle mixture-speed adjustment to get that taken care of, 500-750rpm sounds a bit low.  I would shoot for 850-900rpm.  Maybe the "LS" guys and gals can chime in and give you a better answer regarding the idle speed.

[Julio A.]

Hey, I have the same symptoms in my R65. The tranny has this sound which only worsens when hot but goes away as soon as you pull in the clutch. I've checked the transmission oil a lot of time and found no signs of water contamination and no metal flakes in the magnetic plug; only fuzz. Regarding the transmission, I have no idea what to look out for.  :-/

[Luca]

Thanks Mike,

I think you're right about two different problems.  I got a bit paranoid when they showed up at the same time.  Gonna go over to my friends where all my tools and manometer are and sync them on my way to work.  Might also try adding some more gas to the tank (although what's in there is fresh, it's possible to get bad gas  [smiley=embarassed.gif])

As for the transmission, I did spin the wheel through all the gears with the clutch pulled.  I can hear stuff turning, but nothing sounds or feels crunchy.  Neutral spins very quietly, and that was where I was noticing the noise.

I think I'll just pay attention to the sounds for now, and pull it over if it starts to get louder.  Also found this article on micapeak, which comforted me a bit and might be of interest to some folks here:

http://micapeak.com/bmw-gs/trans.html

[Mike V]

Luca,

Sounds like a solid plan.  Keep an eye on the noise and magnetic plug and as long as it doesn't worsen what you may be hearing is normal wear amplified by out of balance carbs.  And any changes in gear shifting characteristics may also be a warning sign.

Make sure that speedo cable boot is in good condition, especially if you water wash your bike. You probably already know; pressure washing is never a good idea as water will find it's way into components.

As I mentioned before; these transmissions can be a bit noisy - the key is determining when it becomes too much.

[Luca]

Yep, I dont use hoses on bike components unless they have been removed.  Speedo boot is original, but I put silicone on it before I put it on the road.

So heres the deal...  an intake side backfire must have blown off my left vacuum cap, resulting in poor idle.  I currently have the rubber airbox valve plugged, since it was shot, but I'm ordering a new one this weekend.  Didn't hear the vacuum leak until I pulled into the gas station (and when I had felt for the cap the other night, I guess the wiggly end of my glove finger felt like the rubber nib)  So, feeling like an idiot, I resynced the carbs anyway, but they were pretty much fine.  Just took in a bit of slack on the right throttle cable.

The tranny still rattles, but only when hot.  Kind of sounds healthy, to be honest.  I think this might be attributed to my new motor mount torques.  Everything still runs smooth.  4th gear whine is maybe a tad more pronounced, but ill play with motor mount torques before jumping to conclusions again.

check all the simple stuff first  [smiley=wall.gif]