During a 3,900 mile trip to Las Vegas and back my bike developed an annoying rattle on start up when cold (metal on metal sound). It started doing it about half way through the trip which had me very concerned. The rattle would go away after a few seconds of starting the bike. The rattle seemed to be coming from the right side. If the bike was warm, there was no rattle on start up. It didn't take much to warm up in the heat we encountered on the trip (106 degrees in Vegas) and stay hot. The bike ran a little sluggish in the heat, which really didn't surprise me. The EITMS kicked in for the first time since I got the bike. The stop and go traffic didn't help on the strip in Vegas.

At first I thought it might be a loose motor mount because the heat was unbearable at times and maybe the mounts softened up in the heat. To make a long story short I continued on home. The bike was acting up a little at slow speeds with delayed throttle response (best way I can describe it). Other than that it ran really good when I got into better temperatures.

When I got home the first thing I did was change the oil. Started it up and the rattle was still there for a few seconds. OK, off to the dealer to see what the tech has to say. Of course it wouldn't make the sound now when he looked at it because it was warmed up. He suggested it was coming from the throttle body and of course it was "Normal" with the work I have had done to my motor.

So back at home next morning I remove the air filter and fire the bike up while looking into the throttle body. I couldn't believe what I was seeing. The throttle plate was rattling. Just for a few seconds. The 2 small screws on the throttle plate were loose. So I tightened up the 2 small torx screws on the plate. I only snugged them up because I have no idea what the torque spec is. Went back to the let the tech know what I found and he was adamant that that could never happen. Well it did. I went for a short ride and the bike has much better throttle response. Just like it did after I had the motor done. I guess over time the screws had worked loose.

Scary thinking of what might have happened if the screws were to have come out completely and sucked into the intake. I can only imagine that just one of them getting sucked in would make one hell of a mess.

 

I think every time I read this forum,I find another thing to check on the bike!
Thanks for the tip-did you put a little tiny bit of locktite on them?
I have seen this problem on car carburetors before.

 

Funny you mentioned this because I have my A/F off and while I was bored today sitting in the garage, I saw the two tiny allen heads holding the butterfly on and figured, why not, check them for tightness...They were tight but with all the vibration these bikes produce, it's worthwhile to check all fasteners from time to time.....

 

I was a little worried about making a mess with locktite because the screws are so small, so I just snugged them up. One was 1 full turn loose and the other about 1/2 turn. They didn't turn real easy so my guess is there is locktite on them already.

 

On all of the carburetors I ever worked on, the throttle plate screws were peened on the threaded ends so even if the screws were loose, they would unscrew to a point, then the spread out part would stop them from unscrewing any farther. I would assume that is the same for Harley throttle bodies also.

 

That is probably true. I didn't look at the backside. Next time I have the filter off I am going to look.