Ducati Sporting Club UK > General > Idle Chat > 2 smoke bikes

[rockhopper]

Am i right in thinking that a two stroke bike with an oil pump might seize if you change down at high revs becasue with a closed throttle the pump doesnt pump but the revs are still high? Is that why race bikes dump the pump and run premix?

How likley is this to happen on a road going two stroke?

[Twinfan]

I think you're right, and it depends how often you close the throttle fully at the redline and how fit your oil pump is. If it's running a leaner oil mix than it should then you'd seize it. On the road it's unlikely to seize I guess, but on a track you may push it over the edge.

At least I hope so. Must remember to top up the Silkolene on the RS250....

[rockhopper]

Perhaps with the lack of engine braking on a two stroke you wouldnt tend to change down as early as you would with a four stroke?

[keefer]

it will still pull enough oil and fuel through the cylinder due to the induction.
I thought they dumped them on race bikes because it doesn't need to be user friendly / practical.

[Spen]

We dump them on race bikes as they sap power, can break and we mix our own fuel/oil so we know we're getting the right amount in.

Yes, they can seize if you run too long on a closed throttle, that's why you should always cane a 2stroke............

[Edited on 23-12-2004 by Spen]

[crm250]

The pump on my RGV SP VJ23 is controlled electronicaly and is not controlled by cable like most strokers. This keeps on pumping when on the overrun, but with limited fuel being drawn in i guess it could still seize. On the road in reality i suspect you have more chance on winning the lottery.
On a dyno seems to be the favorite place to seize on the over run.
Saying that on the VJ23 us owners have other perils to worry about like failing crank seals on the right hand main bearing (built into the main bearing) but hopefully the belching of smoke out the right hand pipe should give that one away easy enough