Fitting R27 cylinder barrel to R26

[BSA Bob]

My R26 motor goes to the mechanic soon & I'll ask a question I touched on in a previous post.
I have a spare R27 cylinder barrel in better external condition than the R26 item on the motor. The bores of both barrels are in poor condition & will need work. I've heard the R27 units provide better lubrication. Since both barrels will need work, would it be better to repair &  fit the R27?

[BSA Bob]

[Heiko]

Hi Bob,

the R 27 cylinder has two opposite holes at the bottom of the cylinder. The R 26 had only one. However, I do not know whether this was already introduced at the introduction of the R 27 or only with the introduction of the 15mm oil pump on the R 27. However, I drive an R 27 cylinder in my R 26 with the 10mm pump and have never had any problems.


Regards Heiko

[Hans Otté]

Hi Bob
here is my long ago (bad)experience with a R27 barrel (two lubrification bores) mounted on a R26 housing body.
Only if the R26 10mm oil pump is in good shape you may mount the R27 barrel. Otherwise the oil pressure can show deficient to the upper parts in the head of the engine, (valves an moving items). First check the condition of your installed oil pump and then decide what barrel you restore for new use on your motor.
Normally, the R26 barrel is just the perfect fitting to the R26 engine block and today, with the knowledge i have on the matter,  i would prefer to install the engine as it left the factory plant at the time. Do for the best, *****

[Dieter57]

My english not so perfect, Answer in german.

Hatte mir ja einen neuen Zylinder für die R27 verbaut.
Bei diesem ist nur eine Bohrung vorhanden, bis jetzt keine Probleme damit.

[rolf]

dann ist es ein 26 Zylinder

[Hans Otté]

dann ist es ein 26 Zylinder

Yes sir.
That is how i would proceed in this dedicated case! Only my oppinion, *****

[Dieter57]

dann ist es ein 26 Zylinder

Anscheinend macht der Hersteller keinen Unterschied.
Wie bei den Schalldämpfern.

Bei Ulis und Mayer gibts nur die Ausführung R26 und R27

Wie gesagt, bisher keine Problem Rolf

[rolf]

bis auf die 2. Bohrung ist da ja auch kein Unterschied....und die kann nachträglich anbringen oder auch nicht....so wichtig ist sie nicht

[rolf.soler]

The R27 had the 2 holes right from the beginning as far as I know, but the 15 mm oil pump was introduced much later, after many thousand R27 with 2 holes and 10 mm oil pump.
I guess Rolf is right   it does not make much of a difference. But it is also a fairytale that you need the 15 mm pump in a R27 (with 2 holes in the barrel). If the pump is bad, however, oil supply is maybe to little, no matter how many holes there are...

[rolf]

Ich kann dir nur in allen Punkten zustimmen, Rolf

[cledrera]

Wurde Rolf D befragt?
(Nur echt mit dreifachem Rolf)

[BSA Bob]

Thanks for all this. I don't know which oil pump I have yet. I'll discuss all the parts with the mechanic.