Hitchcocks Forum

Hi all, having fitted a Mk2 32mm Amal and free flowing exhaust system to my 2007 Electra I am getting some popping in the exhaust on the overrun. Pretty sure there are no air leaks in the exhaust, so think this is a mixture problem, albeit I rather like the noise There is no spitting back from the carb. I have set air screw at about 1 and 1/8 turns out (from fully screwed in). Just wondering if anyone has any experience and can share their knowledge. I also recall a product called Colourtune from my misspent youth - is this worth using?

I had this when I fitted the Mikuni pumper carb to my Electra-X. After taking extra care to seal the exhaust I still had some popping to deal with on overrun, but fitting a bigger pilot jet stopped it.

Regards,

A.

I agree with Adrian, if you're tuning to one and one eight turn out then the pilot is slightly weak or restricted..

One and a half turns out should be closer with correct pilot..

Having said that has yours the pressed in bush or replaceable jet?

Checked the inlet manifold for air leak i expect..

Tzen,

Pilot jet should be set to give you highest tickover speed and then throttle stop adjusted to give the tickover speed you want - as per tuning notes. If you just set it to a particular number of turns out you will be very fortunate to get it where the idle mix is correct.

Hi Paul, ok, I will try that, understand I should adjust air screw until the tickover increases no further, then back off slightly. Seemed ok with standard exhaust, which is when I did the original set up, but with freer flowing exhaust the mixture is possibly now too lean. I have used a soap solution to check for carb leaks and all appears to be ok. This is very much a learning experience (or in some cases relearning from 30 years ago!) so appreciate all the help and advice.

Tzen, Yep to be more accurate when I said pilot jet I should of said air screw. With the motor warmed up put some slack in the throttle cable, move the air screw in or out till you get the revs to increase, then drop the slide with the throttle stop till it ticks over as you like it but not too slow. Then do it again untill you can't get the revs to rise, it slows down either in or out. Re adjust the throttle cable. If you are outside the 1 to 2 turns out it may be worth changing the pilot jet, remenber you are moving the air screw so in = richer, out = leaner.