2 stroke and gearbox oil

[back off road]

the pump is for convienience , surely if it was the b all and end all 2t bikes would be auto lube

[garyd]

To fit a pump is extra £ss,but there is no getting away from the fact that the pump is actually the b all end all ,it takes the guess work out of it

[twistednuts]

Even with a pump, goin down a very long steep hill on a 2 stroke requires a blip on the throttle.
Its the only time the engine revs high without throttle use, hence not enough oil to lubricate.

[back off road]

no guess work, accurate measurments of fuel and oil ,simples

[garyd]

[quote="twistednuts"]Even with a pump, goin down a very long steep hill on a 2 stroke requires a blip on the throttle.
Its the only time the engine revs high without throttle use, hence not enough oil to lubricate.[/quote]
You havent followed any of this have you ??the pump is set up to give a constant /controlled oil feed at ANY engine speed /revs,do you honestly think a bike that is ticking over is MORE likely to sieze than a bike that is being ragged silly?this confusion over more oil is a schoolboy error and THE reason why soooo many premixed bikes sieze "ill give it a bit more oil to be safe",read up on oil/fuel mixtures by volume till you get a handle on the subject,till then use a pump!!

[twistednuts]

I beg to differ. The pump is set to give a certain amount at tick over. It is then governed by the throttle.

For simplicity lets assume half throttle is 5000 revs. At this the pump will give out say 5 drops of oil.
Now lets say it pumps 1 drop of oil at tickover.
When you go down a long hill under engine braking, the revs may get to 5000 revs with no throttle use, hence only getting one drop of oil instead of the required 5.

If im wrong i'll hold my hand up, this is just how i presume the pump works

[twistednuts]

I also wouldnt add extra oil 'for luck' to a pre mix, cos i know it weakens the mixture.

[garyd]

Ok lets draw a line under this ,you blip away ,ill run me pump with closed throttle down hills

[twistednuts]

Ok lets draw a line under this ,you blip away ,ill run me pump with closed throttle down hills

Ok, sounds good to me.

[back off road]

and i will keep mixing it myself

[lgingell]

the pump is driven by the engine, so at 5000 rpm the pump will be turning pretty fast - regardless of if the throttle is opened or closed.

the pump is ALSO governed by throttle opening

so to recap

THE PUMP OUTPUT IS CONTROLLED BY BOTH ENGINE SPEED AND ENGINE LOAD(THROTTLE POSITION)

[knackeredMk1]

Also remember that a closed throttle doesn't mean the pump is closed. In fact you will find that the pump is still open a significant amount when the throttle is off.

[twistednuts]

Oh, i thought we'd laid this one to rest.

Its a fact that 2 strokes have a flaw with lubrication. Engine braking just isnt good for them, whether theres a hill or not. They prefer more time with the throttle on than off.

Im even gonna stick my neck out and say pre-mix is better, simply because with the correct mixture you get the correct amount of oil at all times. Autolube is convenient, but has drawbacks - it relies on a cable, which can fail or stretch. Do you check for correct pump operation every time you start your bike?

And with 5000rpm with throttle shut you dont get the same amount of oil as you do with 5000rpm throttle open, if you did the mixture would be mega weak and oil rich. The throttle determines the oil flow, the engine just makes the pump.. erhhh .. pump

[john7780]

i would just say buy a premixing bottle off fleabay and do it the old fashioned way

[back off road]

john +1