Timing issue?
Thread Starter
|
Novice
Joined: Jun 2012
Posts: 17
Likes: 0
Timing issue?
So with some shitty weather in the north east I though it was time to do some things to the old 73 sporty that might have been a little overdue. Heres what I did.
-adjusted clutch
-removed and cleaned carburetor
-adjusted push rods
Went to fire bike back up and wont start. Turns over and fires up for a few seconds but shortly after dies out. Sometimes will shoot fire and backfire out of the carb. Went back and checked the pushrods and adjustment was still good (used ironmicks advice) removed carburetor bowl and checked that. Reassembled carb and tried to fire it up again. But the same issue, im thinking maybe the adjustment set my timing off? Is that possible? any ideas would help. thanks guys
-adjusted clutch
-removed and cleaned carburetor
-adjusted push rods
Went to fire bike back up and wont start. Turns over and fires up for a few seconds but shortly after dies out. Sometimes will shoot fire and backfire out of the carb. Went back and checked the pushrods and adjustment was still good (used ironmicks advice) removed carburetor bowl and checked that. Reassembled carb and tried to fire it up again. But the same issue, im thinking maybe the adjustment set my timing off? Is that possible? any ideas would help. thanks guys
It is not likely that the things that you did [pushrods, clutch, carb] would affect the ignition timing.
However, flames and backfire out the carb is usually a timing problem. Still have points in there? I am not much experienced with them, just what i have read on these forums, but i would go there first. Ensure that the parts are not worn, that the gaps are still correct. Perhaps install a new condenser.
However, flames and backfire out the carb is usually a timing problem. Still have points in there? I am not much experienced with them, just what i have read on these forums, but i would go there first. Ensure that the parts are not worn, that the gaps are still correct. Perhaps install a new condenser.
Stellar HDF Member
Joined: Feb 2006
Posts: 3,035
Likes: 17
From: Houston Texas
So with some shitty weather in the north east I though it was time to do some things to the old 73 sporty that might have been a little overdue. Heres what I did.
-adjusted clutch
-removed and cleaned carburetor
-adjusted push rods
Went to fire bike back up and wont start. Turns over and fires up for a few seconds but shortly after dies out. Sometimes will shoot fire and backfire out of the carb. Went back and checked the pushrods and adjustment was still good (used ironmicks advice) removed carburetor bowl and checked that. Reassembled carb and tried to fire it up again. But the same issue, im thinking maybe the adjustment set my timing off? Is that possible? any ideas would help. thanks guys
-adjusted clutch
-removed and cleaned carburetor
-adjusted push rods
Went to fire bike back up and wont start. Turns over and fires up for a few seconds but shortly after dies out. Sometimes will shoot fire and backfire out of the carb. Went back and checked the pushrods and adjustment was still good (used ironmicks advice) removed carburetor bowl and checked that. Reassembled carb and tried to fire it up again. But the same issue, im thinking maybe the adjustment set my timing off? Is that possible? any ideas would help. thanks guys
The gap on both cam lobes should be set at .018.
if you have a wider gap than .018, that in effect advances the ignition timing and could cause the backfire. Although I have to say that is a stretch.
Nothing you did is going to affect the ignition timing at all.
If there is an air leak at the carb/manifold connection or the manifold O rings leak air ......that could cause the problem you are having.
Did you just remove the carb, or did you remove the intake manifold as well?
pg
Thread Starter
|
Novice
Joined: Jun 2012
Posts: 17
Likes: 0
i removed the whole thing manifold and all (where my ignition is its easier) i noticed when putting the manifold back on that it doesnt necessarily go into the heads it just seemed to sit there with the orings sealing the gap. am i wrong with this?
Stellar HDF Member
Joined: Feb 2006
Posts: 3,035
Likes: 17
From: Houston Texas
Your problem is an air leak with those O rings.
Trust me, this is the problem.
First of all, remove the carb from the manifold if you have already not done so.
Then hold your manifold face against either the front or rear face of the head.
Now look at the air gap at the face of the other head. It will be approximately 1/8 inch wide but the important thing is this.......... Is the face of the head parallel with the face of the intake manifold?
If it is, you are good.
If it is not, then you need to line the faces up.
You do this by loosening the 4 nuts on the base of the cylinder.
Use a plastic mallet to bump the cylinder base around so the line up is parallel, then tighten down the 4 nuts.
Now you are ready to install the manifold.
Take the O rings and roll them back over the intake manifold.
Position the manifold between the two heads and roll the first O ring into position over the gap.
Put the clamp around the connection and lightly tighten the clamp.
Do the same thing with the other O ring.
As you begin to tighten up each clamp, keep feeling inside the manifold.
The O ring should feel smooth and even all around the joint.
If you feel any bump or distortion of the O ring then that is going to be a leak.
The clamps should be snugged down but do not over tighten them. That will cause leaks too.
This is going to be a real pain in the *** but you need to do it.
Once you feel both O rings are smooth and evenly positioned install the carb and crank it up.
Be sure to install the carb brace BEFORE you start the engine.
Using no carb brace is another cause for an air leak.
Let us know how much fun you had installing these O rings and getting them to seal.
pg
Thread Starter
|
Novice
Joined: Jun 2012
Posts: 17
Likes: 0
thanks for the instructions i didnt think it looked right when i did it but wasnt sure. ill try tomorrow when i have a little more daylight left and be sure to update you guys
Trending Topics
Stellar HDF Member
Joined: Feb 2006
Posts: 3,035
Likes: 17
From: Houston Texas
Yep, that is your problem without a doubt.
The air leaking causes a lean mixture and that results in the backfiring out the carb, and the engine starting, and then dieing.
If your air leak was not as bad as it is now (but still leaking air) then the result would be the engine would start but would have a very high idle speed.
It would be either a high idle speed or the engine would die when you try to reduce the idle speed.
So watch for that 'after you finish sealing' the air leaks.
Sometimes you think you have it whipped but there is still a small leak and that is the reason I describe the symptoms of a small air leak.
Right now you have what I call a large air leak.
pg
The air leaking causes a lean mixture and that results in the backfiring out the carb, and the engine starting, and then dieing.
If your air leak was not as bad as it is now (but still leaking air) then the result would be the engine would start but would have a very high idle speed.
It would be either a high idle speed or the engine would die when you try to reduce the idle speed.
So watch for that 'after you finish sealing' the air leaks.
Sometimes you think you have it whipped but there is still a small leak and that is the reason I describe the symptoms of a small air leak.
Right now you have what I call a large air leak.
pg
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Southpaw Super Glide: A Left-Hand-Drive 1979 Harley FXE Built to Fit the Rider
Verdad Gallardo
Tourer
Joined: Sep 2010
Posts: 342
Likes: 0
From: western slope Colorado
also might double check that you didn't mess up the float setting when you took the carb apart. always check every thing twice before putting all back together. advice comes from experience
Thread Starter
|
Novice
Joined: Jun 2012
Posts: 17
Likes: 0
Thanks to Pg my bike starts and runs like a top again. After micks pushrod and pg's carburetor help its safe to say my bike is back on the road. now if I can only get that damn brake button to stop breaking on me life will be good. thanks again guys