Rejetting with Emgo mufflers

[RevrdMark]

Hi friends, the rainy season is getting close to an end here in the Pac Northwest, so i'm getting to all the jobs that i didn't do last year because i was riding

So anyway I put on some little emgo mufflers that are practically straight pipes (very low restriction) . I assumed i was going to need to rejet the carbs for them, but after i got "Cranky" running i didn't want to tear into the carbs again. So anyway the plugs are very dark and wet and i can tell from the smell and deposits on the exhaust that it is running very rich. So I have been doing a search through the forum but i'm not finding the info i need.

So in rejetting the (what i assume) are stock jets in the carbs for a straight exhaust and running rich, do i go smaller jets or bigger jets?

Thanks in advance guys.

Mark

 

[16VGTIDave]

When changing to free flowing mufflers, theory says one would need to increase the jet sizing as the air:fuel ratio would have been leaned. But you report running rich, so either the mufflers don't flow nearly as well as the stock mufflers, or you have another issue that has cropped-up.

My first thought is to strongly suggest cleaning the carbs and checking the floats. And while you are at it, check the valve adjustments.

A couple other thoughts: Is it possible that you had the choke on? Did you get the bike up to operating temp (the oil hot, not just the cylinders)?

 

[RevrdMark]

You might be right i was thinking the same thing that these mufflers should make it lean. I may need to check the floats or the valves.

 

[bcware]

I have pod filters and emgo shorty pipes. I didn't go more than +1 on the pilot and +2 on the main jets. The pilot could possibly be bumped, but the the mains are just right for 60+ degree F weather where I am. When I bumped the mains higher it just started choking the engine at WOT.

Also, the needle clip position on the emulsion needle is at the stock setting. My '78 is fully adjustable.

I agree with checking out the things dave mentioned.

 

[Scorpio1963]

Hey guys is there anyway you can do a sound clip with youtube so i can hear what those mufflers sound like?thanks.

 

[bcware]

I've tried to make a video before and it just doesn't work; unless you have high end audio recording equipment the low sounds simply don't get picked up. Suffice it to say that the sound is good, especially after the mufflers were re-packed with better fiberglass. The inspection station clocked me at about 86 dB if I recall correctly; the limit is 106 dB here. It's loud, but not crazy.

This will give you an idea:

 

[Scorpio1963]

Sounds pretty good there BC Thanks for the clip.Was that with the pipes without the crossover inbetween or with it?

 

[bcware]

My '78 does not have a cross-over. The two pipes are totally separate.