GS 650g katana, Gear or shaft "howling"

[Babyblue_katana]

I have a GS 650g Katana which functions perfectly, except for a distinct noise from the transmission, it sounds a bit like a worn differential on a car. The sound is most noticeable in the 4th and 5th gears, and it only appears when the bike has to provide tourqe. What could this be?

[Zooks]

Where exactly is the noise coming from?? This is very important because being a shaft drive you could be headed for CATASTROPHIC failure.

Give us as much info as you can and the questions / answers will flow forth. There has been much discussion on this forum about shaft drive problems with GS's.

I'm not trying to scare you but you need to be careful. You don't want the back wheel locking up at high speed.

[Babyblue_katana]

It appears to be coming from the left side. I have had the bike for a cpl of months, and the noise have been consistant, not better not worse, no clanking or vibrations though. I became aware of it when a friend tried it and thought it was strange. Needless to say, its my first shaft drive bike, I just hope it doesnt involve taking the thing apart :S

[SqDancerLynn1]

I would check the big nut on the secondary gear set IF loose it could cause howling noise, or the bearing could be bad. Check for play ? In gear - how far can you turn the rear wheel ?

[tkent02]

Is there any oil in the final drive?
Secondary gear?

[Zooks]

We need you to be much more specific. Does it do it under acceleration, deceleration? Is it coming from up near the motor, or at the back wheel? As TKent said, have you checked the oil levels? Does it leak any oil, whatsoever, from anywhere?

This is potentially a very serious problem, we need you to help us to help you. Some basic maintenance could save you from wrecking your bike.

[Babyblue_katana]

I will check the final drive oil level as soon as I can.

The sound is only audible during acceleration, and it becomes louder as I go up through the gears.

After some acrobatic riding without helmet, hanging halfway down the left side of the bike I think the sound is coming from the area with the rubber boot (bad joint?).

My bikes gears (primary, secondary) seem to share the oil, and thats pretty new oil, and the level is constant, so I'm not losing (or using any).

The rear wheel has very little play in gear, almost none.

Zooks I'm definately not using the bike untill I've resolved this. I hope this information is better.

[Zooks]

Check out Basscliff's website for heaps of servicing tips on shaft drive bikes. http://members.dslextreme.com/users/bikecliff/

These two pages will be of huge benefit to you. http://members.dslextreme.com/users/...s/reardiff.pdf & http://members.dslextreme.com/users/.../bevel_oil.pdf

These bikes are famed for stripping the drive at the rear wheel (final drive) which is why I asked where the noise is coming from. If it's coming from the 'engine end' (secondary drive) then it's likely an oil issue. This oil is seperate to your engine oil and always gets forgotten .

Either that or you need to adjust the backlash in the secondary gears. This is usually only an issue if someone has had the shaft out of the engine, but it will cause enormous amounts of whining (usually under decel though).

Have a read and check both 'drive' oils and let us know. Remember your bike has three seperate oil reservoirs. Engine, secondary gears and rear hub (diff).

[TheCafeKid]

ANother thing to actually have a look at besides the lash on the drive and driven gears is the bearings in the gear housings themselves. Thats what finally killed the GK I have with 140,000 miles on it. The gear faces themselves were OK, a little chewed on the ends from the fact that the bearings blew out, and were causing the gears to skip off of eachother. If you check the lash, you'll likely have to pull the gears out to do so, so dont forget to check those bearings... And, just an additional point, not too long before the secondary box bit the dust on my GK, i started noticing a howling sound, or a loud whine i guess. I couldnt really isolate while on the bike, and it didnt really make that much noise while running it on the centerstand, so I just assumed it was probably some tranny noise, after all it did have what ammounts to a KaJillion miles on an air cooled motor...I was wrong...

[lilbilly]

Either that or you need to adjust the backlash in the secondary gears. This is usually only an issue if someone has had the shaft out of the engine, but it will cause enormous amounts of whining (usually under decel though).

Have a read and check both 'drive' oils and let us know. Remember your bike has three seperate oil reservoirs. Engine, secondary gears and rear hub (diff).

When you say backlash, what are you referring to actually?

Also, by checking these oils - do you mean just to drain them and replenish or is there a way to check if the oil needs replaced?

Sorry if these are dumb questions, have a shaft drive myself and want to make sure I'm good.

[TheCafeKid]

When you say backlash, what are you referring to actually?

Also, by checking these oils - do you mean just to drain them and replenish or is there a way to check if the oil needs replaced?

Sorry if these are dumb questions, have a shaft drive myself and want to make sure I'm good.

the "lash" he is refering to are where the gears contact eachother on the gear surfaces. Ideally you want them to contact at dead center, so there is the best possible amount of surface area for them to drive or be driven on. It basicly boils down to shiming them out or in so that you achieve that desired "lash" If they contact mostly on the front edge of the gears, you need to remove shims to get the gear further in, if they contact on the back edge, you need to shim them out....The manual explains this quite well. If you dont have one for your 650, I have them for the 850/1100 im sure they're pretty similar.

As far as the oils go, (and my experience is on the 850/1100, but its prolly pretty much the same) on the secondary box you need to pull the shifter cover off. There is a drain plug behind it. Drain the old oil out. It will take a lil while, and it will be kinda messy, so get a nice wide pan and stick it under the bike. Pull the plug and go have a beer or watch tv for a lil while. Then, when you cant see it draining anymore, replace the plug. On top of the secondary box, right near the stator cover and just below the carbs, there is a big bolt. Thats the filler hole bolt. Open that up. Now, somewhere near the shifter, above it and just behind it you will see a screw headed bolt. Thats the fill level plug. I think it even says it on the case. Remove that plug as well. Take your gear oil, and you DO use gear oil (80 weight i think) and pour it in the filler hole just untill it starts to leak out of that fill level hole. Stop pouring and let it settle, then pour a lil more in there till it does it again and stop. Replace the two plugs and your shifter cover, and ride! Dont over fill the secondary box!

[waltfen]

650 is slightly different. It does have a drain plug near the gear stick but the secondary box uses the same oil as the engine/gearbox.
When you do an engine oil change you take both drain plugs out as opposed to one on the other GS's. Replace them and then fill up as normal.
Personally I would check the final drive it sounds like it's running dry - next problem would be where has it gone?

[Zooks]

650 is slightly different. It does have a drain plug near the gear stick but the secondary box uses the same oil as the engine/gearbox.
When you do an engine oil change you take both drain plugs out as opposed to one on the other GS's. Replace them and then fill up as normal.
Personally I would check the final drive it sounds like it's running dry - next problem would be where has it gone?

I never knew that about the 650. That is very interesting. I hope we haven't given babyblue a 'bum steer'. This is why having a manual for each particular bike is so handy. I never knew that the 650 was different to larger 'shafties'.

[waltfen]

Here's the manual info :-

[Babyblue_katana]

Update!

I checked the final drive oil, and its all there + some, and it looks like new.

I then pulled the rubber boot back at the engine-end of the shaft and some 100ml of very rusty looking oil came out, I already know what that means (leaky rubber thingy at the bevel gear), it must leak slowly though since my oil level in the engine is constant so far.

I guess I have narrowed it down to the 2nd gearbox (Dammit...DAMMIT ), that fix will probably cost more than I paid for the bike