Westfield Megabusa Build Diary

02 Jan 2008
Scavenge pump pulley assembly

Now the dry sump is fitted the scavenge pumps can be fitted which pull oil out of the sump and into the remote oil reservoir. This is a lot more complicated than it sounds though - it runs off the engine like an alternator does, but you have to extend the rotation of the crackshaft out so that the pump can make use of it. Luckily Westfield's dry sump kit has an excellent solution to this.

You start by removing the starter motor drive cover and are immediately faced with gears and other stuff that you would be a bit reluctant to disassemble, but then immediately you learn you have to remove them. Luckily I have the workshop manual for the engine if I get stuck.

You then take off the starter motor clutch cover next to it, allowing the whole unit to be removed which roughly resembles a figure of 8 shape. On the larger of the two covers, you need to remove the centre cover which covers a bolt, and you replace it with the Westfield supplied insert which has a hole in the centre for a shaft to run through it.

Now the bolt needs to come off the starter clutch, but you will find that turning it with a ratchet will turn the engine instead of loosening the bolt, so you need to shock the bolt off. Strike the ratchet with a hammer a few times instead of pushing with your hand and the bolt will free itself.

The pulley drive flange has 3 drive pins which fit into the starter clutch now that the bolt is removed, and you quickly start to see exactly how the whole set-up works. You need to insert the 2 roll pins into the drive flange before fitting into place. I found the best way to do this was with 2 people, a pair of fine nosed pliars, and a small hammer.

Once the pins are in place, the pulley drive flange can be offered up to the starter clutch, and secured into place with a few taps of the hammer. once this is in place, the starter clutch cover can be put back into place with a new gasket, and you quickly see why you had to put the Westfield part had to be fitted to the cover - the pulley flange pokes right though it. With the pulley fitted to the shaft, you can tighten everything back up again.

A new bolt needs to be fitted to secure the pulley assembly into place - you can get this tight, but it will spin the engine before you hit the specified torque (like when you took it off), so don't use threadlock yet. You can tighten it when the drive flange is fitted to the engine - read on to the later section for details...


The starter motor drive cover and SM clutch cover. Both covers removed along with some of the internal components. A selection of items that come with the dry sump ready to be fitted.
The supplied insert fitted into place on the starter motor clutch cover. The pulley flange shaft pokes through here. The pulley flange fitted to the starter motor clutch and the covers re-inserted (fit the pulley before you do this - I had to take it all back off again!) The pulley secured onto the starter clutch.