R27 Cylinder Head oil flow

[Daniel Andrada]

Hello,
How does the oil gets into the cyclinder head rocker arm bushing. Is it supposed to be forced feed by way of the right side bolts of the cylinder head holding the rocker shaft? Is there a hole on the rocker shaft and the rocker block for this purpose?

[Allan Atherton]

The manual says:
"... The oil tube pressed into the cylinder barrel supplies pressure oil to the rocker arm bushings..."

[Daniel Andrada]

Thanks Allan,
Is it normal to have just trickle of oil coming out of the rocker arm block for the pin and bushing to be lubricated?
Also I found out the tappet guide is quite worn out where the tappet slides. Seems there is not much or no lubrication at this part.

[Garnet Grylls]

It is normal but not good to have just a trickel of oil at the rockers. The R27s have 2 holes in the base of the cylinders to add oil to the cylinder walls to help cool the piston.

BMW found that this extra cylinder lube caused poor oil presure in the head, so as of frame no. 381133 the oilpump capcity was increased by changing from 10mm gears to 15mm.

You can find some rocker arm mods here:
http://www.bmw-einzylinder.de/forum/ind ... ic=2085.15

I was seeing the same wear on my R26 so I upgraded to the R27 pump and added the oiling tubes to the rocker bases. I have over a 1000km since then and the wear seems to have stopped.

[Daniel Andrada]

I plan to use the old oil pump drive shaft assembly when I upgrade to 15mm gears and housing. Is it possible just to make the necessary modifications on the drive shaft by machining? If, so what was changed? the length less by 5mm?

[Garnet]

Yes you may shorten the drive. I cut off the shaft to the new length and filed it square to match the oil pump drive. The new shaft is more than 5mm shorter.(I cannot remeber the exact length. I think 8mm). When you compare the two pumps side by side it is easy to see. The newer pump has a bigger housing as well.

[Daniel Andrada]

Garnet, thank you.
Based on the service bulletin, the gear casing and the two gears inside were replaced. The casing cover remains the same. From this, I gather that they made the casing taller.

[Garnet]

Sorry for the slow answer. Check out this thread and follow some of the links in German.
http://www.bmw-einzylinder.de/forum/ind ... pic=1604.0

It seems that the drive is just 5mm shorter. I used to be able to remember these things.
Garnet

[Daniel Andrada]

Garnet,
Thank you for providing great info and links. now I have to save for those parts needed for the conversion.