HarleyTechTalk

98 Road King carbarated, I replaced the rear cyl head gasket reassembled everything went for a ride and it ran great.  Bike sat a couple of days and when I took it out it started popping during acceleration. I thought I had a intake leak so I tried the carb cleaner and propane to find the leak and no change in idle speed.  Any thoughts on what to check next or another way to find a leak.  Thanks in advance

Check your plug wires. Check your plugs.
Does it pop during both gentle and hard acceleration?
Does pulling the enrichener make any difference?
When you twist the throttle, is a steady stream of fuel shooting into the carb from the accelerator pump?
A compression test on both cylinders might help identify an issue.

Is this popping back through the carb or elsewhere? If elsewhere, maybe a loose exhaust pipe at the head or exhaust gasket issue since the repair.  Did you retighten them after they were heat cycled?
 Hopefully it's not a pulled stud but maybe the head gasket?

Plugs look good, it doesn't pop if I'm easy on the throttle until the engine gets to temperature then it will die until it cools down. Popping thru the exhaust only.

Quote from: Sparkey1961 on February 10, 2023, 03:46:15 PMPlugs look good

put another set of plugs in anyway 

Got a buddy who's Shovel was doing this awhile back. Turned out his brand new ignition coil had a crack in it, and when the bike heated up to operating temperature, the crack would expand, and the bike would start popping and stuttering and then die. Once it cooled off it would fire right back up and run until it got to temp again.

My first thought is pulled stud. So very common esp if this is the first time the head has been off. Does it do it when at idle you give it a handful of throttle? Compression test is a good suggestion. You can also get a length of fuel hose, hold one end to your ear and go around the perimeter of the gasket and listen for a leak.

-JW

JW-Fine at idle and yes breaks down if I give it a hand full of throttle. This is the first time the head has been off. I'll try the hose idea next and go from there. If it's a pulled stud will a head bolt just be loose/under torqued?  Thanks Sparkey

I thought by 98' the stud problems had been resolved.

Double check your pushrod settings? Unless stock pushrods were re-used.

I believe the 94+ change to the cases helped a ton, but still possible to pull a stud. The symptom sure sounds like a pulled stud.

Yes, a pulled stud loses tension on the head on that corner. Still enough clamp force with the other three to mostly contain at low cylinder pressure but it will leak under load.

-JW

Check the plug wires, especially the 1 that wraps, and is secured under the frame backbone.
John

While troubleshooting I noticed I was getting a inconsistent spark then no spark, turns out the inigition module was going bad.  So I installed a Daynaytech2000i ingition which eliminates the ingition module and it's running fine now. Thanks for everyone's help 

Glad ya got it figured out!