Soot On Startup

[peterd]

I'm the guy with the crazy 4k block, 5k head (and who know what else) high compression 4k.

 

I've been playing with the carby lately and it runs sweet. On startup, I'm getting a good spray of dirty black soot spraying out of the exhaust and then it's clean and not smokey. (dirty particles)

I'm not using oil or water. I think the exhaust is clean when it's running. It used to start clean I think.

The exhaust and extractors are a few months old. There is a small manifold leak. I also changed the spark plugs to a cooler one recently.

any ideas?

 

thanks for your help.

Peter

Edited December 8, 2014 by peterd

[altezzaclub]

So, doesnt use oil (or water) ... how much fuel does it use?

 

Fill the tank right up, set the tripmeter to zero and drive it as usual to the last 10L or so. gas it right up again and work out litres/100Km. Should be around 8 or 9L/100. I'm wondering if its running rich all the time, and especially so at startup.

 

What carbs?? using a choke? pumping the gas to get it to fire?

 

The sooty bit at startup should be normal, it is cold so not burning efficiently, and also rich from the choke at the same time. The cold plugs won't be helping matters, but its not worth changing them if it runs smoothly. Depends how bad the soot is.

[peterd]

thanks

I'll fill up today and see how the milage compares with before.

the carby is a rejetted aisin. (jets are one size up I think)

 

It starts easily with not much choke.

 

maybe it's just too rich. I'll play around with it and inspect the plugs too.

 

thanks

[lexsmaz]

If it starts up easily on a really cold morning with out any or very little choke I would say its running quite rich, have you adjusted the carby idle mixtures

[peterd]

yes I've adjusted everything on the carby. I'll lean it out and see what happens.

(no really cold mornings here in December. It's Perth!)

thanks