Pre-Mix?

[Chris Exelby]

Nice piece in Augusts Classic Bike on a Silk that’s up for sale. They do say in the text that the bike requires a 50:1 pre-Mix as well as the oil pumped through the crankcase. This was news to me as I assumed that the pump supplied oil to the top end also. I can’t find any reference to the need for pre-mix in any of the manuals. Clarification anyone?

[OTR002]

Chris, I'm new to Silks and have no real idea on the correct oiling, but as you say in the manuals it just states to as run 32/1 mix for the first 500-700 miles and then goes into detail on how it's a total loss system and the oil is caught in the petrol mix.

But I have also read somewhere that they recommend 50/1 mix, maybe it's only for the Scott engined bikes?

It does state in the MK1 manual that the fuel to oil ration is 50/1, but that's hard to clarify as it may be referring to the ratio once the crankcase oil is picked up and mixed with the incoming fuel? (Silk manual #1 page 10)

Cheers Rod

[hendred]

My manual for a MKII gives a fuel/oil ratio of 50:1 approx. In Section C1 and advises use of a 32:1 premix for the first 500 miles in the Section on Running-in.
I believe the 50:1 fuel ratio comes from the 50 mpg and 300miles per pint of oil in the MKI manual which comes out at 48:1.
My manual has also been overwritten with an oil consumption of 200 miles per pint which would give a fuel oil ratio 32:1!
The usual confusion in the manuals.  In the end it doesn't really matter what the manual says, as long as the oil  pump / throttle cables are correctly set the fuel/oil ratio is set by the engine. Just make sure the engine is using oil though.