Mixture Screws (Again)

Hi Todd

Yes it's all factory standard.
When using the colourtune it's not a deep blue more of a light colour. Previously it was bright yellow and the bike was not idling well. All six plugs are the same. I was thinking of running some "Forte fuel additive" through them as I've had good results with that on my other bike. It just seems to run very rich to me :huh:

WOW

zoso wrote: Hi Todd

Yes it's all factory standard.
When using the colourtune it's not a deep blue more of a light colour. Previously it was bright yellow and the bike was not idling well. All six plugs are the same. I was thinking of running some "Forte fuel additive" through them as I've had good results with that on my other bike. It just seems to run very rich to me :huh:

Hello zoso.

If you are getting enough air and fuel, it should be a fairly bright blue.

T.

Its a strange one this is.

If you are all standard, then it SHOULD be easier to work out.

The standard air box restricts the air flow to a very high level, which is the main reason our 1300's run rich. A yellow burn is too much fuel & not enough air whilst you need a good "Bunsen" blue burn to be correct.
You do need to carry out the Colour Tune procedure VERY SLOWLY with 1 minute between mixture screw adjustments & only 1/4 turns at a time. Tick over MUST NOT be set over 1000 rpm. The engine needs to be a full temp before you do it too (just checking !!).

COULD YOU HAVE A CHOKE NOZZLE SEIZED OR STUCK OPEN ??

The size of the petrol inlet channels cannot change as they are obviously set, & the only adjustment (for idle) is the mixture screw itself.
This means the issue MUST be lack of air.

Can I suggest you remove the tool tray (air filter top) & the air filter itself & go through the Colour Tune procedure again & let us know how it goes.

That will then confirm if it is an air issue ??

Pete F

The engine was at normal operating temperature when I did the colourtune - and 1/4 turns at a time. The flame was bright yellow when I started and now it's light blue but the mixture screws are only half a turn out so something's clearly not right !!
I did my other bike a couple of weeks ago and it all went by the book - 3 1/2 turns out and bunsen blue. I'll take the tool tray/air filter out next weekend - I don't have time to work on the bikes during the week so I'll update after that.

I'm sure your bike wouldn't run at all if you had done this but...

The exploded diagram for the airbox shows the air filter with the opening and foam seal at the top - towards the tool tray.

This is not the correct orientation and the opening must face downwards.

It might run like this - I don't trust all of the seals In the different sections of the air box. I think the joint between the rear upper air box and the lower air box is very suspect. it's just two pieces joined together with two bolts and no gasket.