Hey gents!

So here's the deal. Got this '93 Dyna I bought a year ago. Bike had V&H dragpipes og S&S Super E. Never ran good even though I tried adjusting it a lot. So during the winter I ran all new wiring (simplified wiring). Also put on a CV carb, Arlen Ness Big Sucker A/C, Supertrapp 2 into 1 exhaust and breather bolts for crankcase ventilation. Fired the bike up and it was coughing and backfiring like hell out of the carb. So a week ago I changed intake seals, put on 48 pilot jet instead of 45 (mainjet is 180) and hooked up VOES. No backfiring, but still a little bit coughing out of the carb now and then, specially when bike is cold. Idles good though.

So now spring is in the air, and I finally took my bike out for a ride today. 43 degrees, but still enjoyable. Bike coughed some during start-up, but went away with the enrichener on. After it was warm and enrichener was turned off, bike ran good . Still had some coughs now and then. Tried adjusting the idle mixture screw, but it did not seem to cause any reaction. No change in RPM and idles just fine. Took out the spark plugs and they seem a little bit lean maybe?

So now I would like to find out why it runs lean and why there's no reaction when I adjust mixture screw. I know I have a bad gasket between carb and A/C, but the way I see it shouldn't be the cause of the problem. But I ordered a new one though, just to be safe. Do you guys have any input on what I should check next? I know I have a bad gasket between carb and A/C, but the way I see it shouldn't be the cause of the problem. But I ordered a new one though, just to be safe. Do you guys have any input on what I should check next?

 

I've had a torn accelerator pump cause coughs. So if yours is wet/weeping take a peek at it.

Something else to consider, is picking up an 88 sportster needle, new emulsion tube, and needle jet if you've got an unknown needle in place. The needle jets can be installed upside down, and if you've ever had an aftermarket jet kit installed some of them come with different number of holes than the stock parts. You can get lean surges if somebody drilled the slide bigger than stock, or have a thunderslide but not the rest of the jets for it.

The idle mix not making an impact in your idle can be either not having the throttle closed far enough, (if she idles down if you can close the throttle manually any further than the spring holds it closed.) a sticking enricher up in the carb body, a too high float setting (particularly if the idle changes between side stand and sitting on the bike) and just a too big slow jet.

Cheers,

Zach

 

What was the state of your carb when you got it? Had it been freshly cleaned and adjusted? All the soft bits refreshed?

 

My personal opinion is take that CV back off and reinstall the E but make sure you are using a 295 intermediate and a 72 main and you will be fine.

 

Thank you guys. Think I have stock needle (see pic), but will order a 88 sportster needle and new emulsion tube. Never checked the float setting, so I might dig in that also. I also remembered that I never checked the intake flanges to see if they're warped, so I will order new flanges as well, just to be safe. But I am wondering though, will I do damage to the motor if I ride it as is? Supposed to be warm and sunny the next two days, and I won't get the new parts before next week.

 

That plug looks like low speed rich, what RPM are you idling bike at?

 

I don't got a tachometer, but think bike is idling at 800-900 RPM.

 

Today's fuels will not leave a deposit on the porcelain like older fields did. You see the black ring on the plug surrounding the porcelain? It's black cause your getting to much fuel... Your not lean.. And as thc said put the S&S back on..

 

Ok. I do see your point, but that white deposit on the tip though, is that not from the plug getting too hot? A too rich mixture could explain why the idle mixture adjustments does not affect the RPM I guess, but would not explain the coughing?

 

I don't see the white tip your talking about... Is your motor stock? If so replace the 48 with a 45 and keep the 180 and go from there. Also Remember that putting a needle from a sporster in that has a different taper will also add more fuel sooner as well as raising the needle with more washers. The S&S does not have as many variables and is all I use... As for the sneezing make sure you don't have any vacuum leaks. Brake clean sprayed around the intake seals and sprayed from the carb side will determine if you have any leaks... Usually you can best pinpoint the spray with the red straw that hooks to the nozzle.