What's in inside a 4FL oil pump...

[41juergen]

Perfect, thank's a lot, will try that too...

[SpookDog]

So, after thinking about what Arrow said about uprating oil pumps for big bores,

Sorry it's an old thread, but!

You don't need to uprate the oil pump for a bigger barrel & piston.
The pump is calibrated to supply the standard carb a 50:1 mix from Idle ~ WOT
You only need to uprate the pump for a bigger carb. You'd uprate it to match the higher fuel/air amount. To keep it at the same 50:1 mixture.
Even then, with modern synthetic oils like Castrol Racing you can safely run at 60:1 or higher (in my opinion) I do and I still get a steady/healthy light spatter of unburned oil out the tailpipe.
I premix though, so I know my exact ratio...

I don't know the different size carbs for different models (my 4hw is 28mm) but Belgarda's run a 30 or bigger Delortto, yes? So one of their oil pumps would supply more oil...

[SpookDog]

Sorry! I forgot to say, kudos on the pump mod. I've just gotten a use Athena 170 top end and am going to be wanting to fit a bigger carb to suit.
I don't know if it's going to live on the tzr or my old dtr yet. I'm sure the tzr would benefit from a bigger carb even as a 125 just because of the higher rev range. I'm thinking of resleeving a 4fu barrel in steel for it though, just because of the better state of tune than the 3mb-p that's on it.
I have no idea what the Athena is tuned towards, higher revs or lower torque?...