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Flushing Out Gearbox Oil


matt_urban
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I have been changing my oil after every ride since i changed the pump seal but the oil is still crappy and bike is not loosing water! can i flush it out fully

Is theresome way maybe take cluth plates out and put a car engine flush in and run it up then drop it out ?

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Seems to always be this way, best you can do is fill it right up with cheapest gearbox oil of the right type you can find, open the drain screw for a few seconds... Run the engine for a minute or so, going through all the gears a few times with the bike on the stand. Make sure to get them revs high in 6th!

Straight off and dump the oil through a very fine filter, re-flush with the filtered fluid, using the same technuique. After using this technuique for a while, if the oil doesnt run clear, then it probably wont anytime soon.

Dont worry about it though, black/grey oil is normal, normally. It's only milky oil you need to worry about!

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Water is heavier then oil so any that sets in the low spots and doesn't emulsify will just stay there. I imagine each successive oil change will remove some more. There's almost always some residual water finds its way into the gearbox just from condensation alone. If the bike isn't going to be sitting for weeks/months but is in constant use then it really isn't going to do any harm as the working bits will get coated with oil after use. If the bike sits unused for a long time then I could see the residual water being an issue. One reason to start and put around in the winter once a week or so.

Be careful as flushing with any kind of solvent could affect the seals and gaskets.

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Seems to always be this way, best you can do is fill it right up with cheapest gearbox oil of the right type you can find, open the drain screw for a few seconds... Run the engine for a minute or so, going through all the gears a few times with the bike on the stand. Make sure to get them revs high in 6th!

Straight off and dump the oil through a very fine filter, re-flush with the filtered fluid, using the same technique. After using this technique for a while, if the oil doesn't run clear, then it probably wont anytime soon.

Don't worry about it though, black/grey oil is normal, normally. It's only milky oil you need to worry about!

As above. But I use any cheap engine oil (10/40 - 15/40 - 20/50 etc diesel or petrol as it doesn't matter) and mix it 50/50 with clean paraffin.

Run the engine up on a paddock stand without the chain on and go up and down the gears a few times (using the clutch to clean the plates off) and then leave it in top with the tick-over turned up until the fan kicks in (10 - 15 mins).

Drain the oil/paraffin mix out (with the clutch lever pulled to the handlebar to separate the plates) and any crap that's in there comes out as is out for good!

Re-fill with your chosen gear oil and I can guarantee it will stay cleaner for longer.

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I was told by a very respected trials bike mechanic to put some of the petrol / oil pre mix in. This bloke knows his stuff.

I decided to be a bit over cautious so I used heating oil (Kerosine), as I have oil heating and a tank with 2000l of the stuff in the garden. Diesel would do the job though its marginally heavier than kerosine. Obviously don't put the gearbox under any load run it for a short while drain it and re do it.

I my Rev 3 I used to use AFT in the gearbox and it worked as well as any other oil. Buy it by the gallon from a motor factors and it's about

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