Motorcycle gearbox and gearbox oil

[HardDriver]

Hi, its a bad if I used a motul 5100 4t engine oil to gearbox instead of motul transoil expert 10w40 (especially for gearbox)?

Also if in a gearbox is 50ml or 60ml lack of oil, also is it affected somehow to the gearbox?


How to know if clutch plates, sprockets or clutch system is worn? Also what about gearbox gear (toothed). What is the symptoms is something broken?

[mentalboy]

Oooh, you have a pre-unit motorcycle. Do tell us more about it

[HardDriver]

Pre-unit motorcycle ? Please tell me more what is that?

[mentalboy]

[HardDriver]

[mentalboy]

Four stroke and two stroke oils burn differently - Four stroke will leave deposits on a spark plug that are difficult to remove

80km should have done no significant damage to other parts (possibly not even the spark plug, check it and see!!)

Clutch gears etc should be fine, you have still used a motorcycle oil, just one that is designed to be used slightly differently.

Whilst 1050ml may be the specified amount, the best way to tell if there is enough is either by using the filler cap dipstick or sight glass (whichever method the RG employed!). 50/60ml too little is unlikely to make a significant difference over a short running period.

If you have problems they are likely to be pre-existing ones or for some other reason. You should have nothing to worry about. Just change the oil for the correct type and it should be fine

[Taught2BCauti...]

I'm a bit confused - I thought that on a 2-stroke, the oil that lubricates the engine is mixed in with the petrol, and the gearbox oil is separate and doesn't get burned!

The first sign of a clutch problem developing, is 'slipping' - where the engine speed increases without a proportional increase in road speed - often accompanied by a horrible smell, like burning fish, from the filler plug. Another clutch problem can be caused by incorrect cable adjustment, which prevents the clutch plates from fully engaging or dis-engaging.

Gearbox problems are usually heard as well as felt - reluctance to go from one gear to another, clunking and grinding noises, etc. but check clutch adjustment before assuming the worst.
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[RhynoCZ]

[mentalboy]

[Teflon-Mike]

Gear-box oil tends to be a heavier viscosity, 90wt typically. Gears tend To run 'sumped' in the stuff, the gears ad bearings sitting i the box with the gears and bearings, that just slosh it around as they turn, it's not 'pumped' around them by a separate pump or galleries or anything.


Four-Stroke Engine oil, will normally be thinner, and a 'multi-grade' viscosity, say 10w40, so it maintain's a viscocity somewhere in the middle when it gets hot; ie it's t as heavy on start up, when cold, and its being pumped around all the little nooks and crannies of the engine, when a thick oil would refuse to flow; but it doesn't thin out so much as the engine warms up, that it flows out from between moving metal, so fast.

Single grade oils tend to be cheaper than multi-grades... so if yu have used engine oil in the gear-box, first off you have probably wasted a bit of dosh on an oil that gives benefits.

As to possible 'damage'? Main difference is the multi-grade engine oil is thinner... means that it's more likely to get squashed out from stuff its supposed to lube when under load and warm, that could result in 'accelerated wear' and or premature failure... BUT... its an RG125... a 12bhp motorbike, it's ulikely it can but that much load on the gear-box, that thinner oil would 'make' it break, in much of a hurry....

In racing, used to be common practice to either run a gear-box on less and thinner oil, deliberately, to reduce the 'drag' sapping power in the transmission, and just change it every race; but then you don't expect race bikes to last high mileages anyway!!

As to gear-bx damage? As said, wrong-oil is unlikely to cause much if any that's at all noticeable, unless the box was fucked already.

When bearings start to wear out, they might make a sort of grumbling or whining noise; gears, will make a distinct whining, which will change i pitch and go through a silent period when you go from power on to power off. BUT, more likely problems are in the selector mechanism; and that will tend to be obvious; falls out of gear under load, a 'sloppy' change that doesn't always 'catch' the cog you want. Sign of wear or damage on the selector ratchet, the selector drum or selector forks.. makes little odds what it is, its a box strip job to sort t.

Clutch? If you have a wet-clutch sat i the gear-oil, and you have used thinner multi-grade, chances are it's bite-piont will be 'wandering' as the viscosity effects the friction between the plates as you load them up to take load. A failed clutch will tend to simply not transmit drive, and just 'slip'. Before it completely fails, though, worn or buggered clutch plates, will start to fail and refuse to transmit higher loads, so when under fl throttle in the lower gears accelerating, normally, revs will go crazy like you had pulled teh clutch in.

Clutch problems can make gear changes clumsy, and hnit at a selector problem, or amplify one.

Stop panicking; dump the 'wrong' oil; put in the correct; adjust the clutch, check & adjust the external gear-link between engine and toe-lever, and do whatever you can to remove any slop in that, then see what you got.
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[stinkwheel]

Many 2-strokes take standard multigrade engine oil in the gearbox anyway.

It's unlikely to damage anything and if it did, not immediately.

The gearbox componants are nearly identical to those on a 4-stroke bike anyway and they use the same 10w-40 as goes through the top end of the engine. If anything, it should cope better in your little stroker.

I would say with a high degree of confidence that putting 10w-40 engine oil in a gearbox designed for light gear oil will cause no problems at all. The viscosity is correct and it's mechanically robust enough to go in a gearbox transmitting more than 10 times the horsepower your bike can produce. It's probably got a load of detergent in you don't really need.

If it was me, I wouldn't even change it.
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