whenever i hit a speed bump or railroad tracks i hear a loud bang under my bike almost like my motor is bouncing. Is there a motor mount or something under there that could be bad its driving me nuts. It sounds like my engine is gonna fall out.

you sure it not your front end bottomin out?

im sure!! itc coming from directly below my fuel tank and sounds like its the bottom of the bike

To eliminate some sort of loose engine, set the front tire at a wall. Start bike. Release clutch lever, then watch for the engine move once it tries to move the back wheel. Do not spin the tire. You are just releasing clutch to load the drive chain to load the engine to watch it move. No movement, who worked under the tank last?

Hub I got the bike at 4000 miles haven't had under the tank worked on yet. This started a week ago maybe I'm going to try your advice and I gotta say I'm shocked as shit to see I got a straight to the point response from you lol thanks.also I did my exaust hub and the kid doesn't mind it but I'm still gonna get pipes if I switch to one pipe does that increase power??

Well...if you haven't resolved it by now...HOW about looking at the rear TOP portion of your fender.Any DINGS in that puppy?Right about at the crossover brake line.Just under...the horn.I can tell ya right now with a fair amount of certainty...IF you are able to hold the front brake,and pump the front forks there...then measure from the distance of the BLACK fork leg bottom(right where the chrome leg goes in) to the dust seal....you should have a measurement of around four something inches.Give or take.A "soft" fork setting(preload) will cause your forks to bottom. ESPECIALLY...when going across RR tracks or speed bumps.Any damage to the top of the fender?

IF you hold the front brake...push down hard quickly on the fork,then she "bounces" back up,and THEN settles again to a lower spot,your preload is TOO SOFT.You do not want the forks to "resettle" after they've rebounded back.They should compress,then rebound and stay.

There's TWO upper motor mounts that are visible along the very front of the motor(about where the valve cover sits)...are they loose?(they attach right there on the frame on both sides).Might be able to reach in there while the pipes are COLD and give em a little tug(the pipes),see if your engine moves at all?Just don't overdo the tugging part...you don't want to loosen yer header!Hell...that may be what your hearing anyway!!!Are your header pipes loose?All the connections are secure?The midpipe and muffler brackets?

I just measured mine...4 inches exactly.Yours 'may' be a bit more or less.I'm 175...this measurement was taken OFF of the bike.If you're heavier...it's gonna make a pretty big difference when you hit a hole or whatever.

If it's done this several times...you might want to inspect your fender attachment bolts on the sides where the factory reflectors attach to.IF those bolts are loose..DO NOT OVERTIGHTEN,just snug up.And inspect that area right there for cracks in the fender plastic.Just to be sure everything is okay.A loud 'bang' could indicate the fender is cracking at those bolt attachments.I know...mine did exactly that.A loud BANG while riding, and then I saw this 3" crack on the left side there while cleaning my frontend one morning.

That plastic right there is fairly stout...BUT....it can be 'squeezed' if you're not careful when tightening those bolts...then she starts developing cracks.

I've also had the "loud bang" like you described...going over tracks and speed bumps.Increased my preload...banging gone!It does sound as if it's coming from the engine...

* Last updated by: blue07 on 7/25/2011 @ 2:26 PM *

brusy, you should have seen what I deleted LOL... Anyway, blue might have something there. Did you ever sag yourself to the bike? Kid going for a ride too? He also needs to set the squat so you both are compliant he doesn't pop off the seat you have some hard setting.

However, we have a one time suspension knock? It's not every bump, right? I have a recent video where I coast into the garage and shut down the door the vid is over. There is a bump that is really a good knocker once I hit that. Most times I stand up for it and she still has that shaDING in the topping out.

I am extra soft because I'm so beat up. I've got tire marks on my homemade fender it burns it just ever so much on that whack in the back. Could it be just your normal front knock? Mine does it every time I return and she shows no signs of any funny suspension worries.

Yes, usually any change to a performance pipe or street compliant pipe will increase some power that is plugged up inside the stock muffler'ing system call it. With a [gun] silencer kind of effect with a more straight out exhaust system, there is where you catch that extra grunt and top end getting there quicker is the idea.

hub youre a trip i cant help but to read half of your posts just to see what and how you respond to people lol. Anyways its funny you guys mention this because i took my reflectors and brackets off and that could be when it started or atleast around that time.Like ive said before i am a bigger guy 300lbs 6' 7" so i may need to do some adjusting. I checked the noise again and its more like a bang with a rattle i checked the fender and no marks or cracks. I get the concept of pushing it down and seeing how it rebounds but how would i go about measuring it by myself?? Between dogo and you two you guys have been a great help youre always the first ones to respond with good trouble shooting answers so i want to thank you guys and my son told me to throw in a thanks to you guys also as i dont touch a part on my bike unless hes there helping me, hes 11 and he helped me stretch it he pained my tail lights and they came out sick ill post pics he installed all of the new spiked faring bolts he changed the oil. I told him i wanted him to research how to gravity bleed the rear brakes after he installed the line sure enough he did it while i was at work i came home and my back brake was on point. I got the bike 2 months ago its my first one neither of us had any idea he would have such a passion for it he reads maintenance posts on his own to learn hes a fan of your hub lol no bull shit. Were going to check the rebound out now once again guys thanks a lot i hope one day i can have an answer to help you guys out!

okay that was quick suspension is pretty tight and when i push down and let it come up it stays up. I really need to figure this out its prob something simple but i know if i bring it to the shop even if its not theyre going to make a big deal out of it and charge me an arm and a leg im gonna keep loking around and see if i spot anything. Hub i did you check you told me to try and the engine didnt move. Im lost, Usually im good at figuring things as i have a great deal of common sense but this is driving me nuts.

You have the perfect helper then.

I got the bike 2 months ago its my first one neither of us had any idea he would have such a passion for it he reads maintenance posts on his own to learn hes a fan of your hub lol no bull shit.

Whom do you think I write for, adults? We still have one guy trying to clear the bubble out of the front master and that was 3 weeks ago, give or take. Now, kid, take a big plastic garbage bag and weight it up. Weigh yourself, cut it in half, there are your two bags of whatever throw it on the back seat with dad.

Who cares where you start, it's a matter of finding two numbers and cut it in half there is your sag. So, to confuse the issue and make the reverse engineering go forward, kid, pick a point on the one swing arm side and then make sure it mirror matches the other side of the swing; these are your two equal reference points.

Go to the top with the measuring tape; choose another mirror matching reference point as the other side of the bike's frame. Dad has you in two bags and buckle my shoe throw those in the bag too like everyone is suited up. So either dad squats with all that baggage and you now find the best number in mm from point A to point B of your upper and lower reference points.

Don't be afraid to go hopping up and down on the bike and take another measurement. Will it come to the same number? Probably not. That is why you do not go bananas ape crying about how you can't get a number? Who cares the mm. This is ballpark with a few mm off is like how many turns to that set ring are you going to be off by. Relax, it's not rocket science. It's be consistent with the measuring and all is well.

Squat Number is? Then dad and weight are removed. It's already on the side stand so the suspension is pretty much extended. Just have dad push the bike up off the stand, don't sit, but now check the static number as the bike is upright on its own. What is that number, sunny boy? Add them up, split in half, there is your mm setting.

Now, there is Dad/Son Base setting. You two want to smooth some corners, tighten from there. More plush and softer? Take a spring a ding wind out or half a wind on the back shock spring load. The screw settings mean nothing when sagging. That fluid was already send no matter you open or close the faucet setting it settled in the spring static.

Make sense how simple the aim is for spring sag?

Without a ride around the block or less, it's finding a needle in the proverbial; did you try this? Was it the mouse? Living quarters getting hot for some little guy squealing? Brake pad rattle? Front end knock you hammer hard on the brake short of squealing it so you can hear the steering knock? Something in the fairing getting knocked on a good one?

Can't tell if it's plastic knock, a floating [brake pad knock] because you are chasing a floating engine that knocks and if that is possible, there would be a chaffing at the mount points. So chaffed, it would powder the paint off, then powder down the aluminum like it was making flour for bread because your goose is cooked about the last ride ago that engine had to buck and forth you lift off the gas and then back on it.

Like a broken motor mount in a car. You first take off hard, that spin of the engine torques the one side. Like tears off the one engine mount and when it does, it lifts off, then drops down after your initial shove down on the pedal. Kind of plains out like your prop enginenergy.

See if the rear axle is set at 92ft./lbs.?

Hmmm...well...okay...you said you're 300.Okay.Your son weighs what?Here you are....your gross vehicle weight for the rear....it looks like 397 lbs front and rear each.That's with a 42psi tire pressure(cold).Basically...you are nearing pretty darn close to the max weight limit...probably exceeding it when stopping(your weight's going forward more onto the front end)This 'may' be causing your fork to bottom.Maybe.IDK for sure.You might have to upgrade your fork springs to a stiffer set.No biggie really.But just trying to adjust the fork action with your present weight numbers might not work.You CAN try increasing preload on the front forks(and back spring).It may be alright doing that.Maybe give three lines showing a shot(up front),along with adjusting your compression from fully clockwise(closed)to around 5,6(or possibly less)clicks out.And your rebound damping from fully closed(clockwise)to maybe around 3,4 clicks out?See if that helps anything.Leave the back alone until you can test the front over some "bumps" or whatever and see if those settings helped.THEN,go to the rear and give that shock spring some preload as well....perhaps around 4,5 full turns CLOCKWISE(meaning,turning the ring from left(away from you)to right(coming toward you)with directly in front of you being 6:00,and opposite(the other side away from you being 12:00).Compression...1 and 1/4 or so full turns out from fully closed...rebound damping,1 turn out from fully closed.See if those adjustments help ya any.DO NOT FORCE the adjuster "screws" in once they snug up while closing.When they "tighten up" some...stop.You'll feel it.The front rebound and compression adjusters have a noticeable click to them.I think only the COMPRESSION screw on the rear has a very mild click to it.(it's the one at the TOP of the shock)(if it doesn't,just go with the turns).The bottom one is the REBOUND Damping adjuster...that one may or may not have a clicking action to it.Just don't force any of them "closed" by overdoing the closing adjustment.Once they stop wanting to turn....stop.

* Last updated by: blue07 on 7/26/2011 @ 1:37 AM *

Look inside the side fairings at the engine mounts, is one of them cracked? Did it have single point of contact sliders on it at some time?

Is the rubber padding under the tank cover missing?

You are just going to have to take the skin off and do an inspection, unless you are sure its not something that will dump you at speed.

hahahaha theres the type of response i was looking for from you lol ill never be able to understand you lol. buuuut privateer made me remember something now you guys can call me stupid if you want but when i was removing my flies there was a triangular rubber piece theat fell from under the tank and i couldnt figure out where it went so i left it on my bench could this be the problem?? im guessing so. Can you guys tell me where this goes?? My rear axle nut is torqued to specs i just extended my swing arm so i know thats on point i did it myself. If this is the problem im going to slap the shit outta my self in the face with a rubber dildo for being so stupid and not asking sooner it was on the bike so obviously it belonged there. I'm ready for the ass chewing hub lol bring it on.

This problem only occurs when i hit a bump thats it!!!! Not when i shift or brake. lol im still laughing i read you post THREE times hub and i give up.

blue even if i hit kind of a slight bump to where the forks barely move it happens Im 100% sure it isnt the forks. Privateer could you check your inbox i had a question for you thanks. Im going back in the garage to look some more and start with a process of elimination to further help you guys help me thanks again

How bout a PIC of this triangular thing?Sounds like the ram duct cover seal...but how that would get off....IDK!!!!

I don't think this was mentioned...how about your steering head bearings?Loose maybe?Need to be snugged up some?IDK.Front wheel bearings okay?A clunk hitting a "bump" could be steering head looseness.If you can get it up off the front wheel...it would be simple to check both wheel bearings AND steering head.OR...you can get er out...get going straight...nice practical speed.Grab your front brake...momentarily that is.Does the clunk appear?Grab it hard enough to make the frontend dive pretty forcefully.Do you see the bars moving in any way when it does that?With any clunking noise?

* Last updated by: blue07 on 7/27/2011 @ 12:49 AM *

just tried it blue did a small endo and nothing i know its not in the front ive checked everything there. ill post a pic soon of it sometime today it sounds like its straight down under the tank at the very bottom of the tank im half tempted to take a video for you guys infact i think im gonna

I didn't get a PM, by the way. Hope you find your thunk sound source!

What sort of padding would have that large a gap between the bump you hear? Anything is possible, but heck, that is a lot of flex.

This is just KooKoo.You stretched your bike....you weigh in at 300 lbs...it's not the frontend.I'm at a total loss here.How about swingarm pivot shaft bearings?Don't suppose THEY could be failing do you?Your shock mount at the bottom isn't hitting somehow is it?See if she's scraped any.How is the engine running?Okay?Check yer oil pan bolt protector.Any scrapes on that?

* Last updated by: blue07 on 7/27/2011 @ 12:59 PM *

I'd check your frame for cracks:

Frame Recall

But @ 300 lbs, a stretched bike, and a stock shock... I'd think you are likely bottoming out.

I don't know if this was asked...or answered...but...does this noise appear on sudden throttle closing in gear?

maaan i really wish you guys could here it im not bottoming out it happens even over the slightest bump blue i gotta thank you for baring with me and continuing to give me things to look for. dogo i understand im heavy for a 9 1/2 inch stretch with stock shock but i promise thats not it, its a really loud rattle when i hit a bump. Hub what do you mean when you say flex? which part of the bike? im gonna rip all of the farings off and snap some hi def close up pics i cant get the video today but def tomorrow. Dogo i took your advice on my rear cowl piece im making i rounded all of the edges out to everything wasnt sharp and straight i think now it goes with the flow og the bikes body lines now thanks for your opinion on that ill shoot you a pic soon so you can see the progress if you would like

http://www.bikesportnews.com Rossi has the flex for flipping flippeeknow and that tube frame is get into the 21 century is what the development rider is saying. I think that is what is going on if that is what you mean by flex? Once again, I am seeing a stock bike with your son on the bike. Kid changes your brake lines and did you ask him yet where the bang is?

Get dad outhe garage. Kid, go to the back wheel. Lay prone on the bike with your head toward the taillight. Make sure the bike is in 1st gear. You got a steel pole or two broom sticks you lay opposite each other through the spokes. You are like lifting a barbell weight, but wait!

Get dad outhe way. Drop your hands on the pole so you warp a towel over the pole(s) so you don't mark up daddy's rims or say they are your rims. This says not to make marks on the bike when working on it. It's not your bike but are still working on it think. Don't be sloppy. Preserve the finishes.

Get dad back in and now let him spot you with another set of ears in the middle of the bike. You are looking for a loose shock mount so it is more you are going to pull up the wheel and swing arm but not load the shock spring. All you are going to do is see if a mount is going to move up and then it loads the spring. Get it? If it's loose but the lock nut is not moving but the bolt is; it can rock like a seesaw going up and then coming down.

Get dad's butt flying off the seat on a good bump, that swing goes the opposite way and ((((Knock)))) when it comes back down is that energy is not going to push that knock back up again. That energy lost the second time again, might be a one knock wonder on the unload and/or load [nor can I tell which without being there]. Could be a loose shock bolt, but then again, it is not from under the tank. And are we past that frame recall with just the few that were out there and not one with 4K miles on them. Especially without that relentless paper trail from Kawi to the original owner.