Choke adjustment and E10

[Keith Clements]

I cannot definitively prove but the Javelin has been very difficult to start over the past few months. Fixed by making absolutely sure both chokes were fully closed. The choke can be fully opened immediately after starting.
I investigated this by pouring a cc of neat petrol into each carb prior to starting. This was after manual pumping, checking for a good spark at the correct TDC and extensive turning over on starter. Now fires on first turn. It always runs very smoothly on idle so did not suspect a mixture issue.
Why this might be due to E10 is counter intuitive.

[CyrilWhite]

Try Esso supreme 99, Esso state this is Ethanol free despite pumps having E5 sticker on. The higher octane may suit your higher tuned engine more than most of us but still worth filling up with this during winter.

[Srenner]

Here in the US of A, we have had E10 for years. Yes, I also have to use the choke to start, no matter the ambient temperature. In warm weather, the choke must be pushed in immediately. In cold weather, pumping the throttle rapidly with the motor spinning pulses the air in the carb, acting as a type of accelerator pump. Just a couple of the tricks to compensate for modern fuel.

The fuel goes very stale after 6 weeks.

Part of the problem is that modern fuel does not have the same atomization characteristics as in the past. Pressurized fuel injection has changed the need for fuel that vaporizes easily.