Can someone tell me what kind of noise a motor makes when it is running lean? I have the backfire on quick de-cel, but still need to know if what I am hearing is lean or just V twin rattle, what ever that is

 

Well you could start by telling us what kind of bike it is, year, etc. And as a first time harley owner myself, you are probably hearing the vtwin rattle.

 

It could also be an exhaust gasket. Reguardless of the year or type.....Check the plugs. If it's white you might be lean, if it's on the tan side.....you should be in range.

A lot of times on decel, you may get some popping ( and in my case 4 to 12" of flames). If your burping your throttle to get the rpm's up to where you think the trannies going to put the motor when you downshift due tothe motor doing thebraking....well the unspent gas has got to go somewhere?

 

You know, I was kinda thinking my "rattle" was normal UNTILL I saw how much it quieted down when I took away a few degrees of timing in the 2200-3500 range. The "rattle" almost disappeared. Adding two bars of fuel in the midrange (PCIII) BOTH boosted my power AND eliminated the rattle. The valve noise you hear when you idle is probably normal BUT the rattle you get on slight accelleration in higher gears is pre ignition. Mine is an 06 and I suspect the dealer either forgot or lied about the Stage one DL he charged me for since my Scoot runs better on a map much richer and with timing retarded in the mid range.

EZ

 

Noise is pretty hard to "discuss". Especially over the internet. You need to have an experienced wrench ride it. Tell him the exact conditions that are happening when you hear the noise (speed, gear, throttle position,slight/medium/hard accelerating? decel?, coming down from what rpm in what gear & at what rpm the noise happens it's all relative)and see if he can duplicate the situation and then diagnose.

There are lots of noises that these Harleys make, some OK some not.

Best of luck.