Ok, so here is todays weird question. I have a 1981 FLT. It runs great, except for one thing that is driving me nuts. On deceleration, it makes what I think is a strange sound. No, it's not a lien pop. Very hard to describe. It's sort of like a miss, but only on decel. Here is a little background and what I have done so far.

I bought this as sort of a "barn find" It's a great bike. I bought it from the original owner who had the engine rebuilt by a Harley dealer, rode it for a year and then his health took a vacation on him. He never rode it again and it sat for a few years. It wasn't running when I got it. I suspect someone tried to start it, because it had a bent intake valve on the back jug. I fixed that and it started and ran well, except for this noise. I suspected it was lien popping, so I rebuilt and re-jetted the carb. No change. I then went through the trouble of retrofitting a 44mm. CV carb. Runs like a raped ape, but no change to the noise. I then took it to our local "ShoveHead Old Time Expert". He says it's one of the best running shovels he has heard in years. He said "what noise?" That's how they sound. He told me if I am trying to make this thing run like an Evo, it will never happen and I should just go buy an Evo. I respect his opinion, but I've never heard any Harley sound like this. One thing he did say he thinks may be happening, is that the timing advance is not going in to retard on decel like it should. Now, I think back to when I got the bike and I found that someone had hooked up the battery wrong. Had the terminals reversed as they were not marked. I did try to start the bike a few times until I discovered this problem.

So here is the question - could the ignition module be fried? I ask a few guys at the Harley dealer and they think it's possible. The early modules (and this was the first full year...) were pretty basic and crude. Basically just rampped the timing advance up and down. If they go bad, they could just be outputting a fixed static setting. I really don't want to spend $100 or more for a NOS module just to see if this fixes it. Other than this noise on decel, this thing runs awesome. Never misses a beat on acceleration or even cruising. Idles good too. Timing is set right, carb is set right, valves are set right, compression is good on both jugs. Just under 100PSI. New Harley Davidson plugs.

Anyone experience this?
Opinions?

 

Replace the advanced weights sounds like they aresticking.

 

Modules either work or they don't no in between , getting the ghost noise on deceleration says fuel system or valves . Do a cylinder leak down test and listen close to each jug for escaping air , though the carb & exhaust valves out the crank vent or the oil bag rings .

I'd also check the float level and condition of the carb could be a dirty port .

 

The ignition he has should not have advance weights but rather the cup unless someone changed it to the 78 1/2 module with weights.

 

Hi Horsetrader, sent you this same message on your page...

I was looking at some of your posts and the pics of your FLT and was wondering where you get your parts? That ride is immaculate!

I just bought my Father's '81 last July and need to do some replacements and "Oil leak" issues.

Thanks,

Paul

 

Hi Paul- I rely heavily on eBay for parts. I have never found a better source for a wide variety of both NOS Harley parts as well as aftermarket. I have also used J&P. They too have a great variety of parts. One other source that can be a great stand-by is Bike Bandit.com. I have found a few very rare NOS parts, such as the tank panel that sits under the front of the seat. That plastic panel is VERY hard to find and they had one. The only trick was I had to search a couple of years newer than mine. Still the same part. Thanks for the kind words. I have just sold the Shovel and moved up to a 99' Ultra Classic. Got tired of wrenching more than riding...

 

Thanks to all for your opinions. I have come to the conclusion that the problem resides somewhere in the head(s). I'm pretty sure it's a valve problem. When I bought the bike, it did not run. I found that someone had been digging around in the engine and had the valves adjusted so far out that the valves on the rear jug clipped themselves and actually bent the intake valve. When I pulled it down, I thoroughly inspected the head and found no other damage. I replaced the intake valve and lapped both valves in. I got good even mating surface on both seats. I put it back together and it started and ran well, but it always made that damned noise. Now being German, I just could not live with that noise. I finally found someone who knew Shovels very well and he suspects that it may be a damaged guide that is causing just enough play to cause some strangeness. Anyway, I sold the bike to someone who has a new set of S&S heads waiting for it, so maybe he will get it resolved.