Running Rich
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Road Warrior
Joined: Dec 2015
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From: CA
Running Rich
I've had several situations where a bike ran lean but this one's a rich one.
Plugs look good - medium tan color. Don't seem to be oiled. Bike otherwise runs great. Blips the way you want it to and no performance issues to speak of.
It just plain doesn't respond much to jets or mix settings, which leads me to believe something's wrong with possibly the float level or something. The float needle seems to be doing what it does (moving up and down - does it do more than that?)
Here's what I know:
- Got the bike it was real lean - had a torn accelerator diaphragm. 42/165 jets (stock).
- Since it has almost open pipes and air filter, changed to 44 jet. Bike was clearly rich - black smoke puffs/smell.
- Strange - why would a bike run rich like this (one turn out from seated on mix).
- So I went back to 42 jet. It's not "as" rich but still on the rich side - I can start it cold easily without any enricher/choke.
So it seems to be on rich side but plugs aren't bad, performance is good, but it's not doing what I "think" it should be doing (running much leaner). The only thing I did not do with the carb is set float level. All the diaphragms are good. I did take out the enricher and clean it - it was in good condition to begin with so it seems unlikely to be a culprit (which usually means it IS the culprit in my world).
Since I probably have to take the carb off again soon - want to see if anyone has any ideas before the next round.
1995 Softail.
Thanks.
Plugs look good - medium tan color. Don't seem to be oiled. Bike otherwise runs great. Blips the way you want it to and no performance issues to speak of.
It just plain doesn't respond much to jets or mix settings, which leads me to believe something's wrong with possibly the float level or something. The float needle seems to be doing what it does (moving up and down - does it do more than that?)
Here's what I know:
- Got the bike it was real lean - had a torn accelerator diaphragm. 42/165 jets (stock).
- Since it has almost open pipes and air filter, changed to 44 jet. Bike was clearly rich - black smoke puffs/smell.
- Strange - why would a bike run rich like this (one turn out from seated on mix).
- So I went back to 42 jet. It's not "as" rich but still on the rich side - I can start it cold easily without any enricher/choke.
So it seems to be on rich side but plugs aren't bad, performance is good, but it's not doing what I "think" it should be doing (running much leaner). The only thing I did not do with the carb is set float level. All the diaphragms are good. I did take out the enricher and clean it - it was in good condition to begin with so it seems unlikely to be a culprit (which usually means it IS the culprit in my world).
Since I probably have to take the carb off again soon - want to see if anyone has any ideas before the next round.
1995 Softail.
Thanks.
Thread Starter
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Road Warrior
Joined: Dec 2015
Posts: 1,416
Likes: 317
From: CA
A bike with stock jets (42/165) and stage 1 setup (pipes/filter) should run lean at 2 turns from set. It makes me think something in the carb is making it run richer.
While it may seem fine - if it's not doing what it's supposed to be doing throughout the throttle range then it could cause me trouble. Plus I want it to run right not just apparently right.
While it may seem fine - if it's not doing what it's supposed to be doing throughout the throttle range then it could cause me trouble. Plus I want it to run right not just apparently right.
Road Warrior
Joined: Jul 2016
Posts: 1,370
Likes: 439
From: va
It is normal to change to a higher # on the slow jet and a lower on the main jet when you change air filters and pipes , a rule of thumb not set in stone
Also check the O-ring under the idle mixture screw to see if it's torn and or hard as a rock or even flat , unravel a paper clip -- bend 1 end to 90 deg and cut off to appox 1/16 inch -- reach down the hole and fish out a washer and O-ring
Also check the O-ring under the idle mixture screw to see if it's torn and or hard as a rock or even flat , unravel a paper clip -- bend 1 end to 90 deg and cut off to appox 1/16 inch -- reach down the hole and fish out a washer and O-ring
Seasoned HDF Member
Joined: Jan 2015
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From: Sandy Eggo's North County
You might want to order a jet kit from Dynojet.
Their instructions say "3 turns out" from seat on mixture screw.
You'll also need to very slightly enlarge the vent port (with supplied drill bit from DJ.) the slide.
Lastly, they'll supply you a new/different emulsion tube. This is key.
Along with a range of main jets, a pilot jet and new needle...
Their instructions say "3 turns out" from seat on mixture screw.
You'll also need to very slightly enlarge the vent port (with supplied drill bit from DJ.) the slide.
Lastly, they'll supply you a new/different emulsion tube. This is key.
Along with a range of main jets, a pilot jet and new needle...
Last edited by NORTY FLATZ; Oct 24, 2016 at 12:37 AM.
Club Member
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From: Beyond Fucital
Did you use the stumble method? Get it warm, turn in the mixing screw until it starts to run rough, then out until it starts to run rough counting the turn this time set it half way.
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Road Warrior
Joined: Dec 2015
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From: CA
I never used the stumble method as my Granddad taught me to tune by ear (as unscientific as it is. But I may just do that to see that it is functioning as expected. Do you lower the RPM to do so or can you do it at 1000 RPM? I saw some instructions to do so with low RPMs and I'm a bit leery of lowering oil pressure, etc.
The mix needle was a good suggestion. I did pull it out and while it was in good condition, since the screw was stiff, I think it was due to the o-ring being stuffed or pinched. So now that is good and eliminated as a possibility.
It's raining right now for second day. That would be great for tuning except that I'm working so can't spend much time on it.
The mix needle was a good suggestion. I did pull it out and while it was in good condition, since the screw was stiff, I think it was due to the o-ring being stuffed or pinched. So now that is good and eliminated as a possibility.
It's raining right now for second day. That would be great for tuning except that I'm working so can't spend much time on it.
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Joined: Jan 2015
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From: Sandy Eggo's North County
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