Hey folks,

I thought I might hit ya'all up here before I trust a mechanic's judgement and tell me it's something more serious than it really is.

I have a '94 CBR 1000F with 73,000kms on the clock (mostly outback/country miles apparently), and due to a busy year behind me I rarely rode it at all, just 550kms for the entire year. Battery went dead flat at one stage so I bought a new one along with a motorcycle trickle charger to keep it happy.

Now, ever since I bought it in 2004 i noticed that when at under 70kph in 6th gear there was always a noticable gear whine(which gets higher pitched as you increase speed) and oddly on some rides it would be louder than others... but once you got to around 80/85kph I would notice the whine would dissapear, though it may just be that it's so high pitched by that stage that your ears dont pick it up.

But after having left it for a few months in the garage up until a couple weeks ago, i decided to go for a cruise and noticed that the 6th gear whine is *EXTREMELY* noisy, much more than I ever remember it before, and the other thing is i can still hear it whining away at 90/95kph.. it's not until i get past 100kph that it seems to drop out. Maybe it's just that i'm more tuned to the noise of it now because i haven't ridden it for a few months, but i could swear it's gotten a lot louder, at 65kph in a residential area it sounds like an always active supercharger or something ridiculous whining away down there.. kinda embarrassing.

A few notes, the bike's gear changes are always precise, never slip or anything.. moving from 5th to 6th is as solid a click as moving between any other gears, but it's only 6th that brings on this horrific whine noise. 5th seems to have a slight slight whine at the low 45 to 60 k/ph speeds too, but it's *nothing* like 6th.

Could the engine oil be the cause of this? Considering the bike's been sitting in a cold/hot garage over the last year for the most part the oil can get contaminated somehow or? - As another point I did an oil change in early April 07. I was told that due to the cam chain/tensioner fault with these bikes i should not be running full synthetic oil, I believe the oil in it at the moment is a full mineral Shell oil; though it may possibly be a half synthetic i can't recall.

I haven't changed the oil mostly because i've just barely ridden it since the last change, and i figured the oil would still be nice and clean as a result (it certainly still looks a nice golden brown colour).

In any case, should i stop riding the bike like it is? am I doing it damage based on the above symptoms or is it a trait of these bikes?

I figure if 6th gear was on its way to death, gear changes would be nasty / it'd slip out of gear etc.. but there's never any of that.. it's perfect in that regard. I'm just worried that these existing whining symptoms will lead to it....

I won't ride it again until I (hopefully) get the all-clear from some of you experienced mechanical buffs in the know... i'm pretty clueless when it comes to the mechanical side of my toys.

Cheers for the help folks.

 

Difficult to diagnose even if one is close to the bike. The whine could depend in numerous things. I would howeverstart to check and adjust the engine balancer, this is described in other posts in the forum in case you not have a shop manual. Well, the shop manual is also downloadable on the site if youlook around.

Hope the issue turns out well for you :-)

 

The whine is definitely not standard - mine's 18 years old with 60, 000K's up and has never whined in any gear. Don't think it's your oil, either
As R1000 says, hard to diagnose, but I'd consider another cause - wheel bearings ! If the bike has high mileage, they may not have been attended to (not too hard a job, and fairly cheap) and as you accellerate, the whine would get worse.Dangerous if left unattended to....
A fellow member, Noe, had a nasty noise which turned out as R1000 says, to be the engine balance shaft, which is often a forgotten item in the servicing......Chapter 10 sect 4 for the balancer (thanks Noe) and if you need a manual, send me yr e-mail addy and it'll be on its way.
Check your chain as well, sometimes a dry chain can cause the strangest noises.....
I wouldn't go to far, or fast, on it until you've identified the problem.
Let us know how you get on.

 

Just some food for thought. Is there a shop in your area that could run it on a dyno tester? Could be a great way to determine where the problem is coming from. I'm wondering if the bearing on the 6th gear shaft may be bad. If it doest seem to be there under the other gears it could be the culpert. when you hear the noise, try doing a few controlled changes, like putting the clutch in or leaning on the bike left and right to see if the "singing" noise changes or goes away. At least you can rule things out of your diagnosing by doing these things. Definitly doesnt sound like oil or engine for that matter, as you would surley get the sound that you are discribing under any gear as it would be a RPM issue and not a speed issue linking it to the drive train.

 

When looking at the shop manual, there is nothing that stands out about 6th gear. However, when riding, you are in the gear longer. I would change the filter and oil. Use good motorcycle oil. You need to use motorcycle oil because the transmission and engine share the oil and the gears crush the lubricating spheroids in the oil. Check the oil for metallic flacks. They show up as silver dust floating on the oil. Also turn the filter over and check for metal.

If you have fill the tranny up with a detergent oil on the last change, it may be foaming and causing a whine.

I would think that the whine would be there all the time if it were the ballancer but , it's an easy try.

Please get back to the forum with your findings.

 

Make sure the chain's not too tight. It's supposed to have play in it (5/8" minimum) when on the sidestand because as the suspension moves through its travel it actually becomes tighter. The play assures that at no time in the travel is the chain ever actually tight, banjo string tight. Err on the loose side for this one, not the tight side.

A certain whine is normal but not excessive whine. Because they are subjective terms, who knows what that means? I'd have to hear it to really have an opinion that's worth much. As a mechanic in a previous lifetime, I developed a saying that, "One man's squeek is another man's rattle".

 

Thanks for all the input guys.... Some of you have mentioned things that I've already checked over / tried. These being things like checking the amount of play on the chain,adjusting the balanceretc.. but I already knew it wasn't likely to be any of those things because as previously described the whine only suddenly kicks in once i've switched into 6th gear, so the whine doesn't happen in any other gear irrespective of whether i'm doing 40kph or 130kph (in 4th / 5th)... but 6th gear is terribly noisy from 40/95kph then the whinedies out.

I'm beginning to think GILL might be right when he said "I'm wondering if the bearing on the 6th gear shaft may be bad. If it doest seem to be there under the other gears it could be the culpert."

The bike's 73,000kms are mostly open road travelling, so it's easy to assume it's spent most of its life in 6th gear... I wonder if it's simply just worn out. Though the bike is still shifting into 6th beautifully, never a struggle or any form of slipping out/ crunching etc.

I might take it to the local bike mechanic later this afternoon and let him go for a ride / give me his thoughts... then i'll go from there.

 

the supercharger effect that you referred to is because of gear to gear contact, the more you put load on it the louder the whine.. I just took a look at the diagrams and from what I could see its looking like a bearing, if the bearing is worn out it will allow the shafts to move a little causing more contact between the gears making an audible whine.... long story short find out which one or ones are bad and get them replaced

 

Further thought, I would thinkthat if the 6th gear bearing is bad, you might notice it in other gears that run on the same shaft as the 6th gear sprocket. That being said, it maybe more like the teeth on the actual gear are worn from using that gear so much. I used to know an old trick with bad rear-ends on cars that we would stick a couple old banana peels inside the housing to "quiet" down the noisy gears, but I dont recommend using that one! Good luck on your test drive, I hope you find the problem.

 

My 86/87 has the same problem. Started two or so years ago after reassembling the bottom end. At that point I thought it was only the large bearing behind the front sprocket. I have recently had the bottom apart again & replaced the bearings at the ends of the counter shaft. All others were ok. Now over a period of three months the whine has gone to terrible in sixth, bad in fifth & the others just noticeable. I think I will pull it all down in the winter & replace the bearings & possibly the entire gearbox. First I am curious about the oil supply to the shafts. Possibly an oil starvation problem causing it. May be a blockage somewhere or even low pressure (don't think so) orfaulty relief valve? Next is to check the oil pressure.
I agree that it's embarrassing.