Hello fellas. First off I want to say thanks for the wealth of knowledge here at the clinic. When I bought my roadie, it was making a symphony of sounds to include two from the headlight and one from the light bar. Now I've got it narrowed down to just one that bothers me. My bike is a 01 silverado with 25000 turns on her. As far as I can tell the only mods that are installed are V&H longshots. Since I had recently got rid of all the other rattles I've noticed that above 65 I can hear a knock, it starts faintly and gets louder as speed increases. Also it seems more apparent when running into the wind then when I have a tailwind. I have not been able to duplicate it at lower speeds in other gears no matter what the rpm. I am currently running mobil 1 20w 50, and 89 octane cus it was brought up that it may be detonating. I think my bike is running rich, only getting 36 mpg average on mainly highway miles. The jetting will be checked and adjusted accordingly in a week or so when the bak gets installed. Also been running MMO every other tank or so with no improvement. Any suggestions or a starting point would be great. Thanks guys.

Well, it would seem to me that if you duplicated the rpms in a lower gear and can't get it to knock, then you may have something being created by the wind. You say it starts faintly at 65 and gets increasingly louder with speed and it seems to diminish in a following wind. Feel around the bike for something that could slap against anything, mud flap, loose saddle bag, loose heat shield etc. If you are in high gear at 65 you should be able to duplicate the knock if you are in fourth at say, 55 if it is an engine problem. Can you drive it at 65 or above in a lower gear and make it knock to see if it is speed related or rpm related? Could be something in high gear that doesn't get loud enough to hear til 65? Hard to diagnose over the net----jack

It's sounds to me more like it's not the engine knocking but more of something rattleing or cluncking against something. If it were the engine knocking you should hear it in the lower gears also as the engine runs around the same rpm that you hear it at in high gear. You also say that it is more previlant in a headwind which also leads me to think this is the cause. Hard to diagnose just from reading the description but that's my opinion. Does that make sense?

Update after my drive from work. I can dupltcate it in other gears, fourth around 55 or so, and others bike just wasn't warm when I listened for it before. And I wouldn't necessarily call it a knock but more of a chatter or clatter. Also before I left u dumped a pretty decent amount of MMO in the tank and ran the piss out if it. It may be in my head but seems to be less noticeable. Anyway, bike seems to run strong, just gets less then average gas milage. Maybe I just need to ignore it and enjoy the damn thing, lol. Just doesn't seem normal to me. Thanks for the input fellas.

you're running 89 octane? I would try 87. Mileage has a lot of variables. Wrist twist, wind, accessories, etc. Good luck.

Chubs wrote:
Hello fellas. First off I want to say thanks for the wealth of knowledge here at the clinic. When I bought my roadie, it was making a symphony of sounds to include two from the headlight and one from the light bar. Now I've got it narrowed down to just one that bothers me. My bike is a 01 silverado with 25000 turns on her. As far as I can tell the only mods that are installed are V&H longshots. Since I had recently got rid of all the other rattles I've noticed that above 65 I can hear a knock, it starts faintly and gets louder as speed increases. Also it seems more apparent when running into the wind then when I have a tailwind. I have not been able to duplicate it at lower speeds in other gears no matter what the rpm. I am currently running mobil 1 20w 50, and 89 octane cus it was brought up that it may be detonating. I think my bike is running rich, only getting 36 mpg average on mainly highway miles. The jetting will be checked and adjusted accordingly in a week or so when the bak gets installed. Also been running MMO every other tank or so with no improvement. Any suggestions or a starting point would be great. Thanks guys.

Just wondring if the oil your running std pass car mobile 1 20w-50 or mobil 1 v-twin 20w-50 thats meant for motorcycles only ?

Knocking seemswrose undeload into wind vd tailwind,could be ex leak at pipe to head interface esp when you apply more throttle in a headwind.

Could also be a mechnical issue when the motor is loaded more in a head wind that the bottom end is knocking(crank/berains-etc) if in fact that's whats going on.

But the valtrain doesnt know care what load is on the motor ,it will keep making noise if that was case weather your in a head wind with more load vs tail wind with less load on the motor.

Some peope describe detonation as a kncking sound and your motor is knocking even with 89 fuel.

Well what coud happen in your case is since you said motor was running rich and bike has 25k miles on it possibly enough carbon had built up in comb chambers to increase compression some causing detonation whic fits your symtomof more the load then the knocking starts,less load basically little to no knocking.

Try 91 or 93 fuel for 1 tank starting with an almost empty tank so lwer grade fuel doesnt mix and lower the 93 oct fuels rating.

I would also try a heavy dose of seafoam in fuel tank running at least 1.5 oz seafoam perf gal fuel so put in 7-8 oz with your 93 octane fillup The seafoam can reduce comb chamber deposits over when used in that heavy dose in a couple tank fulls which i found out 1st hand on my 06 yami silverado 1700.

But if the the knock is still present post running a couple tanks of 93 fuel dosed up with seafoam each time then i think its tims to chk valve ajd or take it to a reputable yami dealer that knows how to deal with these old shcool v-twins and not just rice rockets.

They can check hot oilpressure,valves,etc to see if they can get to the bottom of it if you cant find the issue.

But its worth trying 2 tanks 93 fuel dosed well with seafoam to see if that clears it up prior to spending a lot more money/time at the repiar shop that the bike may npt need in the 1st place.

These motors seem to be pretty strong and other then svs most caused by overfilling oil or too rich carb setup they are rock solid and dnot generally run into issues with actual bottom end crank/bearing knocking issues.

Keep us informed on what you chkout and what your funding along the way.

Good luck.

Scott

So I've been running 93 octane for the last couple of days along with a heavy dose of MMO and it hasn't seemed to make any difference. It doesn't seem to be getting any worse either so I'm going to continue to ride it until I can get it in in a couple of weeks unless you guys think that's a bad idea. I think I can rule out detonation, when i ride to work in the morning it's only 65 degrees, the motor should be running plenty cool. So I think since it has 25000 miles on it and I bought it with 23000 I'll take it in and have the valves and everything looked at. Can't hurt and I don't know how well it was cared for before bought it or if any if the scheduled maintenance had been done.

At a little over sixty, mine sounds like it is going to throw a rod!! Does the same in other gears, at same rpm... also when sitting still.... Found out it was the vibration at that rpm causing my windshield lowers to make the sound! It Didn't take me long to find it.. But mine would quit after you passed through the vibration point!!