Hello,

I would like to find a smaller jackshaft pulley with 2 or 3 tooth less.

On my setup, this pulley is used only for the oil pump.

I am looking for a smaller pulley to increase the speed of the oil pump espacially at idle speed.

Any idea for that ?

 

The question is why? If its due to low idle pressure then this is a proper bodge around an actual cause.
Equally, have you considered the impact of speeding it up? Cavitation comes to mind immediately.

 

never heard of this mod on a YB engine but it is common on Hayabusa bike engines!

also, the jackshaft pulley is exactly twice as many teeth as the crank pulley and if you're using the distributor cap (or the phase sensor within the distributor body) the sparks will lose sync with the crank position which will be fun

 

I agree with you about finding a cause first and solution after.
When I rebuilt my engine, I checked the clearances of the bearings with plastigauge. I was in the range but not far from the maximum clearance.
I changed the oil pump after the rebuild in a second time.
The pressure at idle is about 1.6 bar (28 PSI) hot.

For the cavitation, I am not sure if we are concerned with oil. I don't expect a big increase of oil pump RPM, maybe something about 10% to 20% maximum.
Mecanically, some people remove the rev limiter and they don't care about the oil pump if revolutions reach 7500 rpm or more.

Good to know about the Hayabusa. For the ignition distributor and the phase sensor, they were removed. I didn't need them anymore with my ECU.

 

plasti-gauge, may give you the vertical clearance but YBs often require the main bearing housings to be line bored as they go egg shaped (easily checked with a bore gauge or often there's evidence of this on the removed shells). i believe that many YBs have had oil pressure / spun bearings / short life post rebuild when this hasn't been checked /corrected.

 

Do you mean, egg shapped for the bearings on the block and rods or the crankshaft ?

I never heard about that.

Yesterday, I had a look on my previous pump which gave the same problem.

I saw the relief valve stucked at the mid way. What is wierd is I was still eable to move the piston with a screwdriver and it came back to the same position at the middle...

I think I will try to change the oil pump one more time with a full check and the core of the piston smoothed and lubricated. On the rebuilt of the engine of a friend, I already saw the piston missing. Fortunately, I am used to check if the pump works propelly before setting the engine in the engine bay.

 

if the crank caps are fitted to the block and then the bolts are torqued up, each of the 5 bores that the bearing shells fit into must be perfectly round and you need a bore gauge to check this. YBs (and some other engines) typically go egg shaped which means that they close up across the parting line so the width becomes less than the height and the bore is egg shaped. the same problem is frequently found in the con rod bores.