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Discussion Starter · #1 ·
I’ve done everything I can think of. Took the carb apart and cleaned/rebuilt it. Changed plugs. Adjusted throttle cables and idle screw - even with it all the way in, the bike won’t idle.

There is a backfire of sorts (more of a puffing than a backfire) intermittently spitting from the carb. I’ve uploaded a video to YouTube. Any ideas or suggestions of what I can look for or what it could be?

https://youtu.be/jBlTM2sORCk

Thanks for any input you guys may have
 

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Discussion Starter · #7 ·
Going to go one by one here:

Did not replace the intake manifold gaskets but they did not look worn. Replaced all other gaskets on the carb.

It sounds like it runs out of fuel to me too. But it will stay running with the slightest turn of the throttle. Not sure what you mean by low float level but this brings up an interesting point that I had forgotten about. When I was putting the carb back together, the eyelet that is cast into the carb broke off. (Where the pin that holds the float in place goes into.). I ended up welding the pin back into place and the float seemed to operate normally, I.e. it would rotate about the pin with ease. Could this be the issue?

Not sure there’s dirt in the carb anymore as I cleaned the ever living hell out of it. Don’t think it’s valve timing as it was running fine until it sat for almost a year. These problems only recently manifested after I tried getting it going again. I’m leaning toward a mix issue which leads to the question: any recommendations on how to adjust the mixture? I followed the nightrider.com instructions but I seem to have caused myself more issues.

Will check the vent line again. Had that and the Petcock off when I took apart the carb so i’ll Check the connections again.

Really trying to avoid taking it to HD but might just have to bite the bullet. Was also thinking maybe just buy a new carb but don’t want to spend the dough if it could possibly be a motor issue. Thanks for the feedback fellas
 

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There is an "accelerator pump". It shoots fuel into the intake {from the brass tube} when the throttle is opened.

The idle mixture screw will {should} affect the idle speed when turn in & out. In being closed{lean}. 2 1/2 turns out, normal. More than 3 turns would be rich.

Idle speed 1000rpm
 

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Going to go one by one here:

Did not replace the intake manifold gaskets but they did not look worn. Replaced all other gaskets on the carb.

It sounds like it runs out of fuel to me too. But it will stay running with the slightest turn of the throttle. Not sure what you mean by low float level but this brings up an interesting point that I had forgotten about. When I was putting the carb back together, the eyelet that is cast into the carb broke off. (Where the pin that holds the float in place goes into.). I ended up welding the pin back into place and the float seemed to operate normally, I.e. it would rotate about the pin with ease. Could this be the issue?

Not sure there’s dirt in the carb anymore as I cleaned the ever living hell out of it. Don’t think it’s valve timing as it was running fine until it sat for almost a year. These problems only recently manifested after I tried getting it going again. I’m leaning toward a mix issue which leads to the question: any recommendations on how to adjust the mixture? I followed the nightrider.com instructions but I seem to have caused myself more issues.

Will check the vent line again. Had that and the Petcock off when I took apart the carb so i’ll Check the connections again.

Really trying to avoid taking it to HD but might just have to bite the bullet. Was also thinking maybe just buy a new carb but don’t want to spend the dough if it could possibly be a motor issue. Thanks for the feedback fellas
So, why would you think it might be a motor issue? Wasn't it running before you started messing with the carb?

The float doesn't just need to spin, it needs to be set to the correct height in the bowl. There is a specific procedure for adjusting it properly. If it is set too low, it shuts off the flow before the bowl is filled properly, but I would think this wouldn't show up as an idle issue.

If twisting the throttle a small amount keeps it running then it seems like a cable adjustment could be the issue. It could also be an intake leak or trash in the carb as already mentioned.

So the big question is "did the bike run before you messed with it?" If not, it could be a jet problem.
 

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1) If it will rev up, its doubtful that there is a fuel supply issue. Open the bowl drain and see if you get a steady dribble out of the drain hose.

2) the transfer ports are very small, and subject to be blocked by particles of dirt. As opposed to gooped up. You'll need to use high pressure air to clear them. And you need to check the idle mix screw seat. Turning that screw down too tight kills the carb. Also double check the screw for a vacuum leak, some times the packing oring gets damaged and lets the idle circuit suck air.

3) That broken float pedestal was a carb killer in my humble opinion. Float level is critical on those carbs. And now you are basically working off of the assumption that the pivot location is unchanged.

4) Use the propane on it and see what actually needs fixing, as opposed to asking these guys to guess!
 

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Discussion Starter · #11 ·
So I just went out there to try the propane and it seemed to be idling fine. The idle was pretty high because I had adjusted the idle screw all the way in in an attempt to get it to idle the other day. So I backed it back out to a reasonable idle and it idled fine until it poofed out of the carb (see my YouTube vid starting at :18 seconds). Once it poofed, the idle immediately died. It seems to me this poofing, whatever it is, is the root of the idle issue. It was readily apparent when riding around as you could hear it and it felt like a sudden loss of power before kicking back in. This issue is what caused me to pull the carb to begin with.

The bike was running fine before it sat for about a year. When I pulled the carb there was a coat of oil on the filter plate and the plugs were pretty oily too when I changed them out.

Could the broken float pedestal be the cause of the poofing? I highly doubt it because it was doing it before I pulled the carb apart and broke the damn thing..
 

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It sure sounds like a piece of dirt in the transfer circuit. But I guess it could also be a spark issue.

Just for shits and giggles, rev it up and slap your hand over the face of the carb. Don't choke it to death, just let it suck hard then release it. After it clears out repeat, two or three times.

After that have a look at the throttle blade. See how many transfer ports are uncovered at the idle position.
 

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Discussion Starter · #13 ·
So I did the hand trick and it seems to have cured the poofing at idle. I let it sit idling for a few minutes and it never poofed or died. So the idling issue “seems” to have been resolved (for now). However, I took it for a spin and you can definitely hear and feel the poofing when riding. It seems to be most prominent during slow speed with a slight throttle. It pops and poofs like crazy. But if I give it more gas, it goes away. Only seems to be at very partial throttle.

I’m extremely tempted at this point just to get a new carb but it would suck to spend $500 bucks and still have the same issues
 

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Have U adjusted the idle MIXTURE?

You are pulling air from some where. Are there EPA tubes from the tank to a canister, to the carb?
 

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Discussion Starter · #16 ·
Toss the carb,,, a broken float pin pillar junks the carb...
A 42 low speed jet with the a/f mix screw out about 3 turns usually runs well,, then set the idle..
Really? Even with the pin welded back in place? It seems fuel delivery isn’t an issue. That sputter that occurs seems to spit out a fine mist of fuel from the carb.
 

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Discussion Starter · #17 ·
Toss the carb,,, a broken float pin pillar junks the carb...
A 42 low speed jet with the a/f mix screw out about 3 turns usually runs well,, then set the idle..
Really? Even with the pin welded back in place? It doesn’t seem to be a fuel delivery issue to me. That sputter seems to spit out a fine mist of fuel when it happens.
 

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Yes... the carb body is now a paper weight...
the pin boss,, is directional.. I think you stsrted or finished from the wrong side and broke it. then you priced the obsolete carb,,, and got sticker shock. 27421-99C,, at nearly $400.. and decided to weld cast zinc..
And here we are...
 

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Discussion Starter · #20 ·
Yes... the carb body is now a paper weight...
the pin boss,, is directional.. I think you stsrted or finished from the wrong side and broke it. then you priced the obsolete carb,,, and got sticker shock. 27421-99C,, at nearly $400.. and decided to weld cast zinc..
And here we are...
No sticker shock here.. just wanted to be sure I wasn’t throwing $500 bucks at something that wasn’t going to fix the issue. S&S ordered - hopefully that resolves the problems. Thanks for everyone’s input and help on this. I’ll update when I get the new carb put on.
 
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