Back fire through carb
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From: philadelphia
Yes, but probably not to the point it'd blow flame out the carb. But that depends on how much throttle you're giving it and at what rpm when it's backfiring.
First, make sure that's not you horn wire laying frayed and un-hooked - it's black too.
Temporarily tie/run a jumper from that black wire to a ground (anywhere) and see what you get. But if runs/starts just sorta ok, go on and investigate the intake fittings etc. You don't want to run one lean from a bad intake leak, especially on break-in. You can overheat a cylinder(s) real quick and waste all the rebuild you just did.
First, make sure that's not you horn wire laying frayed and un-hooked - it's black too.
Temporarily tie/run a jumper from that black wire to a ground (anywhere) and see what you get. But if runs/starts just sorta ok, go on and investigate the intake fittings etc. You don't want to run one lean from a bad intake leak, especially on break-in. You can overheat a cylinder(s) real quick and waste all the rebuild you just did.
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From: NC USA
Reason I stress intake leaks is, I'm not sure exactly how you took the intake/carb apart and /or if you looked closely at the rubber elbows. Thing is, those original compliance fittings equipped from the factory were bad to crack. The replacements (even aftermarket) after '90 were much better. There's sorta a procedure to putting all back together so they seal properly. Simple, but necessary. Good part is, you have one of the "easiest to pull" fuel tanks there ever was on a Harley if you need to re-do the intake.
So try grounding that wire and you'll see a big difference I'm sure. We'll go from there...
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From: philadelphia
Yes and no. Those pipes will discolor (orange to blue) over time regardless, and it's never noticed because of the heat shields. From your other thread I'm assuming you just got it back together.(?) Just running one a minute or so, not under load didn't hurt anything.
Reason I stress intake leaks is, I'm not sure exactly how you took the intake/carb apart and /or if you looked closely at the rubber elbows. Thing is, those original compliance fittings equipped from the factory were bad to crack. The replacements (even aftermarket) after '90 were much better. There's sorta a procedure to putting all back together so they seal properly. Simple, but necessary. Good part is, you have one of the "easiest to pull" fuel tanks there ever was on a Harley if you need to re-do the intake.
So try grounding that wire and you'll see a big difference I'm sure. We'll go from there...
Reason I stress intake leaks is, I'm not sure exactly how you took the intake/carb apart and /or if you looked closely at the rubber elbows. Thing is, those original compliance fittings equipped from the factory were bad to crack. The replacements (even aftermarket) after '90 were much better. There's sorta a procedure to putting all back together so they seal properly. Simple, but necessary. Good part is, you have one of the "easiest to pull" fuel tanks there ever was on a Harley if you need to re-do the intake.
So try grounding that wire and you'll see a big difference I'm sure. We'll go from there...
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From: Poolville
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From: NC USA
okay will do. I didn’t know there was a certain way to put them back together they were such a pain to get in place and fit the carb around the boot. I ended up putting the boot around the carb and fitting them between the heads and bolting them down. Should I take them off and bolt to the head first and fit the boots around the carb next time ? I’ll have or look in the Manuel.
Last edited by t150vej; Feb 19, 2020 at 11:53 AM.
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From: SoCal
t150vej touched on it, are you supporting the carburetor?
The carburetor must be supported because leaving it hanging off the manifold, especially if it has a rubber boot to seal it to the manifold, almost always results in air in-leakage (vacuum leak).
The carburetor must be supported because leaving it hanging off the manifold, especially if it has a rubber boot to seal it to the manifold, almost always results in air in-leakage (vacuum leak).
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From: philadelphia
Hey guys so I got it all back together I got the intake manifold on right with the carb got the bike running good but the rocker box was leaking. So I took that back off and the one gasket wasnt sitting just right so got that straight. Got the bike running and its running good. I ran through a bunch of heat cycles and took it for a short ride it ran good no issues that I could notice. Only thing is its smoking. Not from the exhaust but from various areas on the motor. Like the fins and some bolts and around the rocker box. Im hoping its just oil from the rebuild burning off? . Like I said I didnt notice any issues with it running. Should I be concerned about the smoking ? I plan on taking it for a ride tomorrow depending on the weather.
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