Do I need?

[Brockett]

Advice from a carburettor expert, or just bit of a lie down.
You know when a tune gets in your mind and won't go away? I think it's called an 'ear worm".
What I get are "idea worms" and they are very bothersome.
My latest idea worm relates to E5 /E10 in petrol. I don't know where I heard it and maybe I just dreamt it but here goes.
Ethanol is not as efficient as petrol.
Ethanol added to petrol does not cause fuel injection serious problems. However, the old carburettor is a simple thoughtless tool that measures out fuel by volume and has no sniff testing devices to check that all is well in the exhaust pipe.
The suggestion is that carburettors need bigger main jets, pilot jets, and have their needles raised a notch or so. Sometimes one will do it and sometimes it needs all three to be altered to ensure the engine does not run weak.  If this is true with E5 then E10 may really be a problem.
And yes it could all be in my head but I do feel the VX800 runs better on Esso Super unleaded which has no E5 in it at all.

[Mr Nick]

Super is all I use on my carb bikes now as they all run better on it. I have upped the main jet on the V50 but that's more to do with the pod filters than the fuel - it does run OK on normal unleaded, but there's just a bit more life to her with the dear stuff - more to do with the RON than ethanol I think though. I'm not seeing anything conclusive on what to change if we have to use E10 at some point so a bit of plug analysis alongside what you feel might be in order. I've always thought carbs are set at the leaner end from the factory to nod towards emissions so a size up on the main wouldn't do much harm.

[Brockett]

Thanks Mr Nick 

[kwackboy]

I use my 2001 CB500 every day, this is the 2nd carb model I've owned and since I've owned it I always thought the first one I owned (some years back) ran better.

Although my current CB runs OK, I've always been battling lean running which has resulted in several carb strip's, replacing parts and making sure everything is to spec but despite my best efforts it's still not 100% and seeing this post, I didn't think that it maybe down to fuel changes because the old CB500 is such a good bike. 

I may bodge fix bikes every day but I hardly get the chance to dabble with carbs like I did in my youth on two strokes so it Looks like I will have a try to richen the mixture a little