. . . or "missing" as I would better describe it. It is in an early 2007 Thunder Mountain Keystone and is still under warranty through my local Harley Dealer that it was bought from. I bought the bike because its "90%" Harley and warrantied by through Harley dealers. It is still 100% stock (from Thunder Mountain), exhaust etc. I'm new to the Harley experience and don't pretend to know anything about these engines/exhaust etc.

At 800 miles, it started "missing" and subtley hesitating (and no, not of the engine lugging type). The other symptom was excessive popping and crackling from the Supertrapp 2 into 1 exhaust when decelling. Otherwise, there was no oil leak, no excessive oil usage etc.

I took it to the dealer and theyreplaced the valve seals (and presumably clean or replaced the plugs). That was fine, and corrected the "missing" problem and most of the exhaust popping.

BUT here I am 1500 miles later and it is doing it again. I can only assume that it is the Valve seals again but I don't want the dealer to just replace them again if I'm going to have the problem again in another 1500 miles. I only have a couple of months of warranty left.

I've found several posts here regarding the valve seals and technical bulletins as well as exhaust popping but not much about a RECURRING problems after the seals have already been replaced .

My problem, knowing little about Harley's V-twins is:

1. How do I get my point across to the dealer (when they know that I know nothing) that something must be causing the valves to fail prematurely and I need it fixed now while under warranty?

2. What could cause the valve seals to fail so quickly a second time?

3. Is it possible the valve seals were leaking even after first replacement fix and it just took 1500 miles for the spark plug to foul up enough to cause the engine to start "missing" again?

It is at the shop right now and the service rep has already called once saying that the excessive exhaust popping and crackling is just something the TM Keystone does and that they could perfomance tune it on the Dyno (at my expense). I told her that 3 buddies and I walked in and rode out on 4 TM Keystones last fall and I'm the only one with this problem, so save the "thats-just-how-they-run" speech for someone else.

I then reminded her that that wasn't even the real reason that the bike was brought in . . . it was the engine problem of which the exhaust issue might simply be a symptom. I then got the "Oh, let me check with the Tech".

Either way, I'm not too concerned about the exhaust popping or mild oil consumption, its simply the fact that the missing/hesitating is getting progressively worse and making the bike unrideable. Again, I'm not looking for a definitive solution and changing the plugs is the extent of my abilities (that I trust myself with), I'm just looking for advice on how to deal with the service rep/tech and perhaps some insight to the problem.