Hitchcocks Forum

Hi anyone know which way the timing side oil seal goes, gaiter spring towards crank or faceing timing pinion .

Facing outwards towards the timing chest. Spring always fits on the oil side, in this case the oil in the chest.

common mistake, it also does not help thats is listed in the technical note to mount spring timing cover.



if you mount it this way you risk oil blow by, it will look like your riding a two stroke.



spring crank side is the correct way.

would you mount the shaft seal alternator side inwards also?

the purpose of this type of seal is to keep the pressure in the crank chamber, and to prevent oil to be pulled in to the crank chamber from the timing/alternator side.

Ftting it as correctly shown in the picture stops oil being sucked in on the piston upstroke and overloading the scavenge pump.


Any blow-by from the crank would simply result in air bubbles rising to the top of the timing chest and pressure inside the crank chamber is relieved by the open-to-air one way breather valve and actually undesirable.

Ooh has this opened a can of worms ) I was told the spring faced the oil, I'm in the middle of rebuild here's a pic how my seal looked not completely clear pic but the spring faces towards the timing covet


steve

No 'Can of worms' here, just fit the seal with the spring facing outwards, so that you can see it when the seal is in place in the timing chest. The Bullet is not a two stroke and certainly does not want or need any crankcase pressure. The whole object is to try to keep oil from the timing chest from seeping into the crankcase and possibly causing heavy oil consumption and / or wet sumping. Cheers, Paul.

you don’t have to believe me steve t, but turn it around.

otherwise it would be like inverting the seal on for example a leg of your front suspension.

it wouldn't work that well!



because thats not howe this type of seal works.



like i said “would you invert the shaft seal on the alternator side also?”



the reason why it was mounted the wrong way is of the difficulty to not damage the spring and get it seated correctly.

with a little work around this can be avoided.



of course i do realize that i am on the lossing hand here, as it is written on paper and confirmed by a professional racer that i am wrong.



but sometimes one has to be wrong to be wright.

Sometimes wrong is actually wrong the purpose of the seal is not to keep pressure in the crankcase, the oil level in the timing case when running is up above the seal and it is there to stop that oil being drawn into the crankcase.

The side of a seal with the spring in is the 'business end'. Seals are supposed to be fitted with the spring side facing whatever the seal is meant to contain and prevent the escape of. In this instance, we are trying to prevent oil escaping from the timing chest, into the crankcase. I promise this is the case, no B.S. from B.W., honest!!

Hi t s replaced and motor run for 5 mins no white smoke from exhaust will check sun morning we were getting 200ml oil from crankcase drain plug. Oil seal we replaced had gaiter faceing out. Thanks to all for their help much appreciated.