Think I just about have it dialed in but still pops.
Road Warrior
Joined: Dec 2012
Posts: 1,539
Likes: 692
From: magnolia tx
Yeah but backfiring out the exhaust is usually a rich condition unburned fuel being ignited as it exits, backfiring threw the carb is usually a lean condition but I do agree without exhaust restriction you are going to get some backfiring out exhaust
Thread Starter
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Club Member
Joined: Mar 2018
Posts: 464
Likes: 400
From: Sedro Woolley, Wa
Would there be a way to increase back pressure without sacrificing performance? I can already tell a difference mid range going from 14-12 disks both sides. I don't mind a bit of bumble rumble on decel but it's the snappy pop! I don't like. If I remembered where the heck my 42 stock jet went I'd toss it in, but that's what started the debacle is I was told I was way too lean for my setup, here's the correct jetting, and going down a size didn't change anything.
Just to get everyone up to speed.
I can close the mix screw all the way even with the idle set really low and it won't stall or stutter. If I pass 3 turns then it starts blowing black smoke out the pipes.
When I did the initial tear down, the left side pipe was totally filled with soot. And that was from stock jetting but before I cleaned out the carb.
I do have the stock exhaust as well he gave me with the bike. I don't know the condition.
Indo get an occasional sneeze thru the carb, if I blip the throttle just right.
Spraying ether near the intake will almost kill the bike. And I'm just saying a tiny squirt. Same with if you spray directly into the idle passage on the face.
Decel pop bang only happens at higher rpms, say downshifting to 3rd. Cracking throttle a tiny bit stops popping.
Increasing idle helps a bit but it's too high.
I might just let the pros look at it. I've burned so many nice riding days tearing things apart and not gaining ground.
Like I said I can live with a bit of pop but this isn't right. Wish I could share a video that didn't just have wind noise. I am 100% stumped at this point.
Plus all the contradictory messages I've got private half are you are lean still other half I'm still rich. Lol!! If someone lived north of Seattle I'd buy lunch to go for a short ride with me.
Just to get everyone up to speed.
I can close the mix screw all the way even with the idle set really low and it won't stall or stutter. If I pass 3 turns then it starts blowing black smoke out the pipes.
When I did the initial tear down, the left side pipe was totally filled with soot. And that was from stock jetting but before I cleaned out the carb.
I do have the stock exhaust as well he gave me with the bike. I don't know the condition.
Indo get an occasional sneeze thru the carb, if I blip the throttle just right.
Spraying ether near the intake will almost kill the bike. And I'm just saying a tiny squirt. Same with if you spray directly into the idle passage on the face.
Decel pop bang only happens at higher rpms, say downshifting to 3rd. Cracking throttle a tiny bit stops popping.
Increasing idle helps a bit but it's too high.
I might just let the pros look at it. I've burned so many nice riding days tearing things apart and not gaining ground.
Like I said I can live with a bit of pop but this isn't right. Wish I could share a video that didn't just have wind noise. I am 100% stumped at this point.
Plus all the contradictory messages I've got private half are you are lean still other half I'm still rich. Lol!! If someone lived north of Seattle I'd buy lunch to go for a short ride with me.
Intermediate
Joined: Mar 2021
Posts: 40
Likes: 12
From: Hollister
First off your running too rich for your riding style and engine build. Specially in the low speed circuit.
You need to adjust your low speed circuit better. Why?, because when you adjust your low speed jetting, you should be able to move RPM up or down with the screw adj.
You need to see adjusting in and out where the bike stalls then split the difference for your low speed circuit.
Then, adjust the throttle position to get to your optimum idle RPM.
If done properly, you should eliminate most of your decel popping because now, the throttle isn't completely closed off.
You need to adjust your low speed circuit better. Why?, because when you adjust your low speed jetting, you should be able to move RPM up or down with the screw adj.
You need to see adjusting in and out where the bike stalls then split the difference for your low speed circuit.
Then, adjust the throttle position to get to your optimum idle RPM.
If done properly, you should eliminate most of your decel popping because now, the throttle isn't completely closed off.
Thread Starter
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Club Member
Joined: Mar 2018
Posts: 464
Likes: 400
From: Sedro Woolley, Wa
I'm game to go back to a stock jet. But it was popping with the 42 in there, but that was before I found the torn o ring in the mix screw. Just pissing me off where I put it. Lol!!
Thread Starter
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Club Member
Joined: Mar 2018
Posts: 464
Likes: 400
From: Sedro Woolley, Wa
Total random 2 am thought there. Could I actually add plates to the muffler's to theoretically lean it out that way as well?? I can order the longer screws from ST, as 14 is the max I can run now, and I have enough plates to go up to 24 on each side.
Road Warrior
Joined: Dec 2012
Posts: 1,539
Likes: 692
From: magnolia tx
Don't bother with the 42, jet, start with a 45 If there is no change in idle when adjusting the idle mixture, I would normally say the slow jet is to large, there could be something wrong with the idle mixture jet itself or its packing, turning the idle mixture screw in should cut off the fuel at idle so the carb might be allowing fuel in from an other place it shouldn't be
Last edited by mike131; Oct 5, 2021 at 07:21 AM.
Road Warrior
Joined: Dec 2012
Posts: 1,539
Likes: 692
From: magnolia tx
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Seasoned HDF Member
Joined: Apr 2011
Posts: 6,184
Likes: 2,132
From: W. Texas
I do have the stock exhaust as well he gave me with the bike. I don't know the condition.
Indo get an occasional sneeze thru the carb, if I blip the throttle just right.
Spraying ether near the intake will almost kill the bike. And I'm just saying a tiny squirt. Same with if you spray directly into the idle passage on the face.
.
I like using brake clean and as long of a spray tube as I can get.
WP
Intermediate
Joined: Apr 2017
Posts: 31
Likes: 17
From: UK
If it was me -
CV carbs are pretty forgiving and they will still run ok kind of outta whack. The 2-3 turns out from seated thing is not always applicable to all bikes. My 95 evo with EV27 cam, paughco pipes and stage 1 filter likes a 45 pilot jet with only 3/4 of a turn out otherwise its jerky at low rpms.
Have patience, check everything and you will get it fixed.
- Start at intake, replace seals on both intake ports AND the carb flange seal. Make sure the manifold is correctly spaced on each side and not being pulled closer to one cylinder. Also use a digital angle meter to make sure your carb is lined up correctly with the motor. Torque everything correctly.
- Make sure electrics, particularly coil, ignition, plugs, plug wires and battery are good with no splits in wiring that could cause a problem.
- Double check float needle, float height, float bowl for debris and that carb internals and gaskets are all good and seated correctly.
- Ensure pilot jet and main jet are seated correctly.
- Double check choke plunger is correctly seated in carb and is opening / closing fully and correctly.
- Inspect and replace exhaust manifold gaskets, correctly torque exhaust flange bolts to spec.
CV carbs are pretty forgiving and they will still run ok kind of outta whack. The 2-3 turns out from seated thing is not always applicable to all bikes. My 95 evo with EV27 cam, paughco pipes and stage 1 filter likes a 45 pilot jet with only 3/4 of a turn out otherwise its jerky at low rpms.
Have patience, check everything and you will get it fixed.