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Weird knocking...

11K views 46 replies 10 participants last post by  my12r 
#1 ·
So, I just got my 12 out of the shop; my charging system died on me so I had a new one installed. It rides great and all (with the exception of needing a PCIIIUSB...)... but I noticed when cruising in 6th gear going about 40mph I could feel this 'knocking' through the foot pegs as I accelerated. The more I accelerated the faster the knocking got. I dropped down a gear and couldn't feel it anymore... went back into 6th and it came back... at about 50mph idk if the knocking stopped... or just got to a point where it was too fast to feel... but when I slowed back to about 40mph it was back again. I tried to lay my head off to the side to listen and I could hear what almost sounded like a banging coming from the engine compartment...

... anyone have any idea wtf that could be? Bike feels like it's running just fine and I can only hear it when I'm in 6th and going slow... :puzzled:
 
#3 ·
Right? I have had the worst luck with this bike :lol:

Between my headlights not working... Faulty Batteries... buying a brand new tire and getting a nail in it about a week after getting it installed... my ECU board going to shit... PCIIIUSB dying on me... Charging system dying... etc... granted most of this isn't necessarily the bike, it's still frustrating because it all usually equals the same thing = I can't ride my beloved 12 :angry:
 
#4 ·
You'll have a new 12 by the time you're done...:thumbup: (The silver lining....)

Yeah. My motor has a strange knock in it as well. It appears to go away on revvs but I found that it doesn't. I'm gonna try that idea rundog I think it was gave me about the tensioner.

Yours sounds to be something in the transmission. But if it was missing a tooth, you'd think it'd get worse the faster you go.
 
#5 ·
Might as well go ahead and bore this one out :lol:

My biggest concern is if I should stop riding it (which seems logical) or if it's okay to... because I'm sick of my 12 just sitting... been down for almost 2 months (2 months of not running 100%)... I never know what to do. lol
 
#8 ·
Got a rear stand?
I'd be extremely cautious but it's a way to simulate running conditions
And be able to get a better vantage point.
You might be able to find a mechanics stethoscope at the autoparts store.
Or the poor mans method.... Long hard handle screw driver against your ear...
Just thinking out loud....
 
#13 ·
:puzzled:
... when cruising in 6th gear going about 40mph I could feel this 'knocking' through the foot pegs as I accelerated. The more I accelerated the faster the knocking got.
If the owners manual shows what gear you should be in, it is not in 6th then accel away @ 40 or high 30 mph, the speedo is off say.

Say, I say I say, shift down some gears. You are banging the bottom end and chattering the clutch basket, sir. That is my guess, 'it goes away when I'm in a better gear' sound like it's rider error? :thumbup:
 
#15 ·
:puzzled:

If the owners manual shows what gear you should be in, it is not in 6th then accel away @ 40 or high 30 mph, the speedo is off say.

Say, I say I say, shift down some gears. You are banging the bottom end and chattering the clutch basket, sir. That is my guess, 'it goes away when I'm in a better gear' sound like it's rider error? :thumbup:
Is it bad (probably a stupid question :lol:) to run in too high of a gear? To save on gas I try to get to 6th as fast as I can...

In other news, I listened a little better (hung my head practically right by the engine) and even when I switched gears I could hear the knocking and feel it through the pegs... bike runs fine otherwise.
 
#16 ·
I've come to the conclusion....it's broken. FIX IT!

Yes you can indeed harm the engine/trans running too high a gear at too low a speed. I'm lucky if I make it out of 2nd around town. I usually hold that gear to 45~50. You don't want to lug the motor. Not only are you lugging the engine, you ain't charging your battery for shit. Full output of the stator is at 4k. In 6th gear at 40mph...I bet your at like 1750. You ain't saving any gas at this speed. An engine is at its most efficient point at your peak torque. Nobody wants to scream around at 7~8k so....I'd say 2nd...maybe 3rd gear is best at 40mph...3rd if you don't want to annoy those around you with a loud pipe...

Hell, you could go anywhere in the world at legal speed limits in 1st gear if you really wanted to on a 12R.:evil:

:thumbup:
 
#25 ·
Well, 22Man, I'm not saying you can't run that combination you are used to. I'm looking for that vibration at the feet. How about you go back out, listen to the engine again, but this time, pull the clutch lever in. Did that make a difference in noise? Did it quiet down some?

Maybe I'm hitting the wrong avenue, she makes no difference. If you sync the throttle bodies, you can make 2 more cylinders run closer together. That says less buzz at the bars and pegs.

That says, check your sync. Where are they?
 
#27 ·
When I pull the clutch in the knock goes away completely... I only hear it around 35mph from 4th-6th gear. (At 3rd the bike is revving to high to hear or feel anything distinctive)

Check my sync you say... hmm... I'm a guy who just recently learned how to do oil changes :rotflmao:... but I'll give it a try and see what I come up with
 
#28 ·
You need a manometer to do TB syncing. You go turning screws willy nilly, you'll create more trouble....

Yep, it's a tough concept to grasp, higher rpm better mileage. Think of it like this. That motor in there is designed for high rpm use. It is built and geared to sustain your peak torque around a track. It revvs out at almost 12k....hehe. Look at some of the smaller offerings that revv out at 22k...like the inline 4 ninja 250R back in the day. Never seen one in person, but read about them. Pooped a bit when I read about its redline....Fuel consumption depends on a shitload of variables. Engine load, atmosphere conditions, elevation, ect ect ect ect....

Pulling the clutch in and the sound goes away....hmmm. Possible clutch issue.
 
#32 ·
I think you're on to something with the whole cost comes with repair idea......:thumbup:

If you pull the clutch and the noise goes away....its your plates rattling, cause the engine is lagging. Do it enough and you wear grooves in the basket/hub. Now your stuff is loose, and rattles all the time. A mere assumption, but plausible.

Have you ever driven a car in overdrive, and had a miss in the engine? You can't feel the miss when you are in the normal gears, but overdrive is pretty much direct drive, and you'll feel any tick the motor has in it here. You can't feel it in the other gears cause the torque converter and clutches soak it up. Especially in cars that lock up under 40 (not so common today, but the old C4's bolted to 302's and the turbo350/700R4 in chevys back in the day would), you'll feel every miss in the engine at low speeds.

Being as a bikes transmission is a constant mesh, you're going to beat the hell outta that clutch at those lower speeds where the punch is felt hardest.

All assumption and probably way off as usual. I like it in my world tho. Things make sense.....to me anyways.

:thumbup:
 
#35 · (Edited)
When engine pulse fires, the other pulse is either ahead or lagging the other. This mismatched lag is like a wave. One wave of power explodes, the other cannot catch up to equal it.

If both throttle plates were even, this knock or the lagging knock would disappear. What you hear is the mis-pulse of the throttle plates being out of sync. The chain whips if there is a chain from crank to main shaft.

If there is a gear driven crank to clutch basket, it still remains out of syn. It still knocks as if the chain was whipping from the change in crank speed. Pulling in of the clutch lever stops that pulse. Part of that mass is no longer connected.

If you think about it, there are two air pulses out of the throttle body. One is the throttle plate and the air under that plate. The other is the air screw and the accompanied hole. Those two adjustments need to balance each other or the total sync is null and void.
 
#46 ·
Okay... so I've been testing out this whole 'rev' higher thing and so far this is what I've noticed:

The bike does seem happier running in the lower gears and even in the high temps that have been hitting DE, whereas the bike normally seemed like it was getting ready to over heat, it now runs (according to the gauge) pretty cool. So that's a plus.

Another plus; whereas before if I really wanted to take off when I was already cruising, I would have to drop down a few gears to really get an enjoyable 'pull' without otherwise having to wait for the RPM range to get to a point where the bike would really start to 'go'... now, I don't have to worry about downshifting a ton to get a nice strong pull with a flick of the wrist.

I haven't gotten through a full tank of gas, so I'm still kinda pessimistic about the whole saving on gas thing. Another question... I hear people running the bike at about 85-90 mph for gas purposes... I've been sticking to 70-75 (again, with the assumption that lower engine speed = better mpg) should I too be running around 85-90 for better fuel range?

Now the down fall... despite the fact the bike is running around 4,000-5,000 RPM... I still feel and hear the knock at lower speeds :banghead:


Oh, and another huge plus, one I'm sure Ivor Hugh Jass will appreciate, the vibrations from the bike on my 'unmentionables' when cruising through town has given me a whole new reason to ride :thumbup::crazyloco::crackup:
 
#47 ·
:rotflmao:

As for speed of cruising, anything from 65-100 will consume pretty close to the same fuel, with slightly more the faster in this range you are. You will get your best fuel economy around 4~6k in 6th on the highways.....this is where the bike was geared to be most efficient.

If they made bikes like cars, your best economy would be top cog at 55mph. Not sure if the same really applies to bikes of this caliber tho.

You should have a slight vibration at 4,500rpm. This is good for the ladies. I ride there with passengers. This is 80mph on the highway (standard gearing top cog cruisin).

I would examine your clutch. If you can pull the clutch and it goes away, that's where you start. If taking the drive off the transmission didn't stop the noise, I'd say look at your drive gears on the basket/hub and input to tranny. But you stated the noise stops on clutch in so...this is where I'd be looking myself.

Yep, you need to ride the bike like the machine it is. If you wanted economy and grandpa ridin, you shoulda bought a goldwing....:crackup: These are thirsty monsters built for arm ripping speed.
 
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