Hello again!

As I start to rebuild my 907 IE I want to get sure that the pistons are really in the right direction:

The are some marks on the piston:

S, A and B.

I suppose that B mens Belt side?
A is intake side?
B is exhaust side?

Thanks for your help.

the manual states the small indentation on the piston is the exhaust side.

G.

Thanks- but I have no small indication; just "A" on intake (?) side, "S" on exhaust (?) side, and "B" for belt (?) side.

Maybe its an italien shortcut ?; "A" for Accesso ?,...

Unfortunately there is no description in the workshop manual...

"indentation" not "indication". (die Ventiltasche im Kolben ist auf der Auslassseite kleiner weil das Auslassventil kleiner ist als das Einlassventil).
The smaller pocket on the piston is on the exit side as the exhaust valve is smaller than the inlet valve.

G.

The pistons/cylinder are marked: A - B or C
S= scarico (exhaust)
A= aspirazione (inlet)

Like Nojapan said above, the letter codes stamped on the piston are suppose to match the material letter code on the cylinder. The other letters are the first letters of the Italian words for intake and exhaust. (If you download the shop manual from this site you can read the various languages for the piston section and you can figure out what Italian words match you languge, etc.) The orginal pistons had the same sized indentions for the exhaust and intake valves while the newer replacement pistons have different sized indentions for the exhaust and intake valves. S is exhaust and A is intake. See the picture below of the rear piston and cylinder.

Hello
Follow this link viewtopic.php?f=3&t=4188 and see how I managed to fit the Merlin pump O.K.
Just scroll down the thread and have a look at the photos first, then scroll back and read the description. It's easy .

Good luck.

P.Man

OK, so S= scarico (exhaust), and A= aspirazione or accesso (inlet) and B means type of piston
Perfect

The indentation of A is only somewhat bigger (0,5mm) than S.

Next I will try to make the Valbro pump fit.

So long
Gernot

Finally I managed to buy a new fuelpump. Its a Bosch BMW pump for K100/ K1, which has the same size as the original Weber PI-022.

The first tests showed, that the Bosch pump needs less current than the Weber. I hope the fuel pressure will be the same

In the meanwhile I fixed all the wholes in my rusty tank with tin and made a complete "KREEM" coating to prevent rust in the future. The whole fairing gets repaired and overhauled at the moment, so I wonder if this last point- the fuelpump will work...

so long
Gernot

I actually dress a fuel pump of Peugeot 405 or 505 cars, dont available the original here !

if the bosch replacement for the bmw k bikes isnt available anymore, i have seen the pump from a 1993 model year isuzu trooper and it is very close, i bet it would fit also.........


doug

Try www.euromotoelectrics.com, this company is more of BMW company, but they have fuel pumps and other parts that work on our bikes.

I bought a fuel pump for 907 a couple of years ago from http://www.fuelsystem.co.uk

It is of less diamater than original pump, but as part of the kit there was a foam plastic insert that allowed fitting in the original holder in the tank.

I bought my parts from BMW. The rubber holder of the pump and the filter screen which is located under the pump.
Both part fitted as originals. Especially the filter screen is absolutly the same. I will look for the bmw part numbers and post them.
Also there is an online parts catalog for BMW parts on www.bmwbayer.de. Look for the pump of k100 or k1100.
BMW told me the pump is still on stock for 300 €.
Used ones are very hard to get because the k modells are also getting old and the pumps are starting to fail.
My original ducati fuel pump fitted in the bmw rubber holder perfectly. So the BMW pump must have the same size. Fuel presure is the same and is anyway seperatly regulated. Injectors are still comming from ducati.