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-   -   Ironhead Popping while idling (http://xlforum.net/forums/showthread.php?t=1891540)

Urhahn99 1st June 2015 00:51

Popping while idling
 
I have a 76 ironhead that for the life on me I can not figure out what the problem is. Bought the bike and finished assembling the motor and complete bike. Couple problems running into. I got the engine to start but it pops horribly. Checked cam timing and oil breather timing. With slash on flywheel center in hole oil breather mark is slightly off. Second problem is lining all cams up, exhaust cam on no. 1 cylinder seems about half tooth off the intake cam. Any help would be appreciated.

IronMick 1st June 2015 04:41

Please post a pic of the cams showing the marks. Get down low with the camera so that the view is straight on, not on a down angle. No flash, just soft light to avoid reflections, bright spots, etc.

Under what conditions does the engine pop? at idle? at hiway speeds? on decel? accel? whatever.

See cam install pics in the Stickys. Here's one ...

How to Install Cam Gears in your IronHead
http://xlforum.net/forums/s...d.php?t=239641

Fridge 1st June 2015 04:54

Quote:

Originally Posted by Urhahn99 (Post 5172130)
I have a 76 ironhead that for the life on me I can not figure out what the problem is. Bought the bike and finished assembling the motor and complete bike. Couple problems running into. I got the engine to start but it pops horribly. Checked cam timing and oil breather timing. With slash on flywheel center in hole oil breather mark is slightly off. Second problem is lining all cams up, exhaust cam on no. 1 cylinder seems about half tooth off the intake cam. Any help would be appreciated.

The breather being off a little bit is no biggie. As long as the dot is in the notch by at least 70%.
Timing the cams, to that same timing mark is the wrong way to do it,if that is how you are doing it.
You time the cams with the pinion gear in the 11o'clock position and looking straight on them to line them up correctly.

Iron Mick's request for pics will help very much in determining the problem...

Urhahn99 1st June 2015 11:30

I will try to get pics some time this week when I have a chance to work on it again. I had a old bike mechanic do it twice and swears its exactly how its suppose to be. It starts popping as soon as it fires up. Have not revved it up at all or put it on the road. Thats how bad the popping is and do not want to cause more problems. I also read on here somewhere that the oil breather is supposed to be time at the 40* advanced mark, is this true or just time it tdc?

IronMick 1st June 2015 13:14

From the Stickys. Should be pic's in here ...

Timing the Oil Pump
http://xlforum.net/forums/s...d.php?t=170686

Oil pump timing. Cam timing. Ignition timing. Intake and exhaust leaks. Carb cleaning and tuning.

The Stickys start here. Hours, days, months even, of good reads ...
Technical Stickys Index - TuneUps, ReBuilds, Etc, Etc, Etc
http://xlforum.net/forums/s...d.php?t=465866

ryder rick 1st June 2015 14:29

Need more clues.

Popping in the exhaust? in the intake?

Does it get worse if you gas it?

Popping tops? Popping pills? Popping tags? :^)

Fridge 1st June 2015 17:15

Quote:

Originally Posted by Urhahn99 (Post 5172944)
I will try to get pics some time this week when I have a chance to work on it again. I had a old bike mechanic do it twice and swears its exactly how its suppose to be. It starts popping as soon as it fires up. Have not revved it up at all or put it on the road. Thats how bad the popping is and do not want to cause more problems. I also read on here somewhere that the oil breather is supposed to be time at the 40* advanced mark, is this true or just time it tdc?

Advance mark, the line on the flywheel for stock flywheels.

Obviously you don't have the FSM(of which you should have),so,your next best helper is to read thru the stickies Mick has suggested to get some more insight on these old beasts.

78ironhead 1st June 2015 20:16

Check pushrod adjustment, intake might be too tight making it pop out of carb.

Ferrous Head 1st June 2015 23:32

Quick and easy check.
Put a pressure guage on both cylinders. Check the stickies for the correct procedure.
If they both have a reading within 5 lbs of eacj other it's not cams. push rods or valves in anyway. I will presume since it's a fresh motor they will run somewhere around 170-180.
If there is no problem there it's either ignition timing or fuel mixture.
I'm betting timing. These things are very "finicky (technical term - means you need to be accurate) about ignition timing.
Quick check on the ignition timing problem.
Retard the ignition a tad and see f the problem persists.

Play Carefully
Gene

Urhahn99 16th July 2015 17:13

Sorry guys I havent replied in a while. I figured out my ignition was bad. Coil would fire when key was turned off. Upgraded to the ultima ignition and problem solved. Now to just finish working out the last few little kinks in the bike.


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