Sorry in advance for the long winded post....Want you all to have all the facts.

Bike runs great to start for many months..little hesitation in the carb but no big deal. The butterfly CV Carb choke arm was broke and fuel inlet leaked. Replacement was on the to do list. Started making a strange sound out of the rear jugs drag pipe on deceleration. It did not do it all the time and I started to think it was heat related(its hot in vegas). The frequency of this sound increased over a month or so and then was constant. Found an exhaust leak on that jug and fixed it. No improvement. No performance issues to speak of. Tore into it over a weekend....also ordered a new S&S super E for the project.

Checked the pushrod adjustment and found the exhaust pushrod bent. Of course this caused me to remove the head and check the valve train. Removed valve and found no issues at all. Removed the tappet block for that jug and inspected the tappets and hydraulic lifters. No issues as far as I can see...not 100% sure what im looking for. The book is vague. Bearings look good, no up and down movement, rolls easy, no excessive wear. Cam lobs look fine through the tappet hole. Reassembled with new pushrods and installed new carb.

Runs like crap now....lol. Sound from rear pipe is still present. I have the recommended jets in it, 0295 and 72. Constant popping from rear jugs pipe under a light throttle on the freeway. Also note that from the time I built this a year ago I have had bluing on the front cylinders pipe about 4 inches down, rear pipe has stayed perfectly new. Now the front hasn't changed but the rear is turning golden almost to the tip at the end. Pulled the aircleaner and watched the gas spray in the carb...seems uniform, no issues there. Hard starting as well unless I pull up the enricher. Cant find an intake leak.
It was noted to me that the carb needs to be hard mounted to the engine as well. As it was not when I got the box of parts I was unaware. Currently fabricating mounts from the rocker boxes to the aircleaner.

I do think I have 2 issues here. Some carburation issue and what ever is causing that damn sound in my rear pipe. Could the original electronic ignition be a prob?
Adjusted timing in all directions
Plugs and wires are new

I know I am missing stuff I have tried, but tried to give you all a complete picture.

 

have you tried to swap the plug cable on one end only, so the coil towers fire on the other cylinder?
doing that if your front cylinder misfires, the coil is the problem

 

So move the rear to the front and leave the front one off? So try to fire on just the front?

 

OK you have found a mechanical issue being a bent push rod and you said this

( Removed valve and found no issues at all )

did you use a valve machine and Re cut the valve face -- did you chuck it in a lathe and spin it to see if it was bent ?? how did you determin no issues

i am not trying to be a smart ask i just want to make sure what you checked was done correctly and we wont be chasing tails around

ignition - coil - bad plug - bad plug wire are all suspect BUT -- did you do a compression test and or a leak down test < that one has more usfull info with this issue my guess

the books are guide to a known repair - no place in a harley book does it guess about an issue

 

OK you have found a mechanical issue being a bent push rod and you said this

( Removed valve and found no issues at all )

did you use a valve machine and Re cut the valve face -- did you chuck it in a lathe and spin it to see if it was bent ?? how did you determin no issues

i am not trying to be a smart ask i just want to make sure what you checked was done correctly and we wont be chasing tails around

ignition - coil - bad plug - bad plug wire are all suspect BUT -- did you do a compression test and or a leak down test < that one has more usfull info with this issue my guess

the books are guide to a known repair - no place in a harley book does it guess about an issue

 

Rolled the valve on a metal work bench to look for bent (have no lathe). Relapped the valve. Did not do a compression test but will put it on the list to do.

 

are the lifters hydraulic or solids? There's a different technique for adjusting them. If you replaced a bent pushrod, you should readjust all 4. You never know how the last guy had them set up.

 

UPDATE...Had my local shovelhead expert inspect tappets and lifters. "There like new" Got the bike all the way back together. Did a compression check. NOT good. Front cylinder was awesome 90 PSI...Rear was 5 PSI. SOOOOO added oil to the cylinder and rechecked...no change so most likely not a piston or rings issue. Tore it back down and removed the head. Checked the cylinder walls first....its beautiful. No scouring, burs, scratches or anything. (important note) the last time I inspected the valve and relapped it I did NOT do a leak Check). That was the first thing I did this time. gas POURED out the exhaust valve...no leaks on the intake. Removed the valve and the seat FELL out with the valve...and the guide was loose as well.

So here is my theory. When it got how for the first time here in vegas the seat started to leak causing my noise in the pipe when it got hot. The more times it got hot it loosened alittle more until the leak was constant. Eventually with the lack of compression the detonation was actually happening in the cylinder and on the other side of the exhaust valve causing wicked heat and making my entire rear pipe turn golden.

The seat wont stay in the head at all at this point. Whole head is going into a shop in the morning for a rebuild.

 

UPDATE...Had my local shovelhead expert inspect tappets and lifters. "There like new" Got the bike all the way back together. Did a compression check. NOT good. Front cylinder was awesome 90 PSI...Rear was 5 PSI. SOOOOO added oil to the cylinder and rechecked...no change so most likely not a piston or rings issue. Tore it back down and removed the head. Checked the cylinder walls first....its beautiful. No scouring, burs, scratches or anything. (important note) the last time I inspected the valve and relapped it I did NOT do a leak Check). That was the first thing I did this time. gas POURED out the exhaust valve...no leaks on the intake. Removed the valve and the seat FELL out with the valve...and the guide was loose as well.

So here is my theory. When it got how for the first time here in vegas the seat started to leak causing my noise in the pipe when it got hot. The more times it got hot it loosened alittle more until the leak was constant. Eventually with the lack of compression the detonation was actually happening in the cylinder and on the other side of the exhaust valve causing wicked heat and making my entire rear pipe turn golden.

The seat wont stay in the head at all at this point. Whole head is going into a shop in the morning for a rebuild.

 

glad you have it figured out