I hope this isn't too serious, but the last few times I fired my motor cold, I hear a knocking sound that appears to be coming from the front cylinder, on top. It lasts only a second or less and then it is quiet. It doesn't happen when I fire the motor warm. Any ideas? Thanks, folks.

 

Likley just a lifter that had blead down after it has sat awhile

 

Had a bike come into my shop last week for same complaint...it WAS a lifer, It also had a chirp noise when hot....reall faint chirp---I replaced the lifters and solved problem---however this bike had about 60k miles on it & I ended up replacing the push rods to due to chips on the end of the pushod from the lifter losing Prime when sitting which I beieve was the chirp noise. GOODLUCK
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Thanks, guys, I appreciate the replies.

 

This sounds exactly like the noise I have been hearing the last two starts. Mine lasts a minute or two, until the bike is warm and then it is quiet. Also no knock when starting the bike warm.

Will this cause damage to the bike? Is it ok to drive? My bike has only 3000 miles and is still under warranty.

 

Well if you have lets say 130 of spring pressure and the lifter has lost it's prime and you start it up and it is slamming up and dwon , no that would not be a good thing, If the bike is under warranty I would drop it off and have them repair it. If the lifter is bleeding down over night there is nothing to say that it will not pump up too fast and bump a vavle into the piston.

 

Thanks, I'll bring it in. Althought I am kinda worried after reading some of the post on here about lifter noise, that they are just going to say its normal. I also did my own stage 1 and suppose that I should put the carb and air cleaner back to stock before bringing it in so there is no hassle about that.

 

Acording to: TT258 – August 9, 2006

Primary Drive / Starter Noise Complaints

Several dealers and customers have commented about a “clunking” noise coming from the
primary housing during start up. Most dealers suspect a loose compensator because the
noise seems to come from the front of the housing. Customers tend to associate it with a
starter issue like improper starter drive engagement into the clutch’s ring gear. In fact the
condition they are noticing is what is referred to as “Starter Knock”. This is a normal sound
and condition for all 2007 Twin Cam models.

Changes in the primary drive system increased the diameter and inertial effects of the
rotating components (clutch and sprocket assembly, ring gear, and engine sprocket). Also,
the engine control system is calibrated to start the engine as quickly as possible (short crank
to run times) and to run up to the predetermined engine idle speed as quickly as possible to
provide very positive starting.

Because the engine fires and then runs up to speed very quickly, there is a large torque input
and instantaneous speed differential between the engine and spring loaded compensator
mounted between the engine and the driveline. The compensator is there to dampen the high
torque spikes inherent in a large displacement V-Twin.
Because of the increased inertia in the rotating components in the driveline, their rotational
speed cannot increase as fast as the engine, so the springs in the compensator momentarily
bottom and results in the sound that you hear.
The same sound exists in the 2006 Dyna models, but to a lesser extent. The increase in
displacement to 1584cc increased the torque spike and speed differential in the 2007’s and
causes the sound to be more noticeable.
There is no damage associated with the compensator bottoming.
Identifying characteristics of this condition:
1. It may be intermittent, as it is dependant on the start up conditions and how quickly the
ignition and engine RPM occurs.
2. It will be a single event. Once the starter is disengaged or the compensator is loaded
the sound will stop, unlike a loose sprocket assembly.
3. The condition may be more noticeable on Touring models due to the shorter primary
drive (shaft center to center distance) and associated shorter chain run. The extra
body parts like fairings and saddlebags also tend to reflect powertrain sounds upward,
towards your ears.

Thanks to Nails

 

Looking at the picture, I do believe that his is not an 07.

 

Most here know the problems I had with engine #1 and engine #2 concerning valve train noise. When #2 started making that familiar hard "knock" like you described on start up I switched to "real" synthetic motor oil and haven't heard that particular valve train noise since. In my mind when a lifter looses its oil after sitting a while the noise will be more like I would describe as a "clack - clack - clack" sound for a short time. I believe the "hard knock" has more to do with the lifter not wanting to be pushed up the lifter bore by a bad cam lobe. Just my opinion. This would be easier if we all could hear each other's noises. But then, maybe that wouldn't be such a good thing!