PETROL MIXTURE

[Moises]

[attachment=0]1761948938710.jpg[/att
Seeing the color of the spark plugs, I would appreciate any comments on the performance of my Javelin engine. Thank you

[Forumadmin]

The mixture looks good. In fact very good for a Javelin. There is some carbon on the outside which would build up. How many miles have the plugs been installed?

[Moises]

Thanks Keith. I've ridden 200 km since the last spark plug cleaning. The spark plugs are NGK BP6HS and the carburetor settings are the original Jowett ones except for the needle washers, which are 2.5 mm.

[Forumadmin]

If the car is idling well, picking up without hesitation when putting the throttle hard down, pulling well up a long hill and cruising for 20km at 100kph and then stopping quickly and it does not overrun and it is not knocking or pinking then I would say it is spot on. Jav carbs do not have accelerator pumps and some recommend increasing the size of the main jet but really 'if it ain't broke do not fix it'. viewtopic.php?p=47627&hilit=main+jet#p47627

[Moises]

Thanks Keith, the engine performances are as you say. I'll leave it like that.

[David Kemp]

This is probably not applicable to you, but may give you an avenue to check in the future.
My son tuned my car with a large engine analyser machine, we then went for a drive with his portable analyser & found the compensator needed changing.
It seems real driving gives a very different reading than a stationary reading.
Possibly you could find someone with a rolling road to tune your car: or buy an old portable machine as they are fun to play with.

[Moises]

Thank you David for your topic.

[Nick Webster]

I agree with the previous comments and the plugs look pretty good to me . The ceramic is quite pale indicating good combustion while the soft soot around the edge of the plug suggests that it is not running too hot. Really, plugs should be checked from an on load state. If you don't have access to a rolling road you can do a "running cut". Drive around for a while and then find an empty bit of road. Drive normally but turn the ignition off when driving at a steady speed and coast to a stop. Then have a look at a plug. Of course it follows that since the carburettor jets are a fixed size, all will be well if there's no air leakage past the throttle spindle and the float chamber level is correct.There has been previously been discussion on this forum about micro drill checking the jet is not restricted.

Nick

[Moises]

Thanks Nick for your good advice