Triumphrat

black&chrome · 09-13-2009, 02:00 PM

I understand if you change the exhaust system it often requires the jetting to be changed as well. I have a standard 76 bonnie - except traded mufflers for the 60's style straight throughs a fair while ago. It runs that way alright, but suspect it to be a bit too much on the rich side, as the pipes are pretty sooty and there was a pretty good amount of carbonization in the chamber when it was stripped.

are there any jetting rules we could add to the tech section?

thanks

GrandPaulZ · 09-13-2009, 02:21 PM

Black plugs = rich

White plugs = lean

Ten thousand variations in between, depending on the variables any given bike has, and the elevation above sea level.

I think we have a couple of basic threads on doing plug chops, I've posted at least 369 of them...

black&chrome · 09-13-2009, 03:35 PM

thanks - I'll try to read through more of the posted answers - but I guess it's a bike by bike answer and there are no hard fast rule about pipe changing requiring a change of jets rather than just raising the needle/ adjusting the mixture? I also have a set of K&N pancake air filters to further add to the consideration

all the best

thirdbike · 09-13-2009, 04:16 PM

Better breathing on intake and exhaust generally necessitates enriching the mixture. As you are still running rich, you may have the wrong and/or worn jets

UnmarkedBill · 09-13-2009, 05:42 PM

Of much importance is sorting out which circuit in your carb(s) is rich. This is also a much-covered subject. Open pipes will make your mixture leaner (though not by much on my bikes,) but if your idle is rich, you'll have black plugs despite running lean. If your needle is wrong, you can have black plugs despite running lean at open throttle.

Get the idle mixture right, then the needle and needle jet, then the main. No matter what, you've already won by ditching the Honda pipes.