Engine noise

[hughes]

Got my top end up and running today. My bike has been down since jan. Started it today with new top end and notice a rattle up front or in the cylinder. Shut engine down and let it cool restarted and set my idle speed. After two cool down cycles I went for a ride. The noise is still their but I went for a low speed easy through the gears breakin in the top end. Next I removed the pipe and took a pen light to look into the cylinder exhaust side of the piston was great and I could see about 75% of the cylinder and every thing was fine. Made sure i had the copper washer between the pipe and cylinder. Went for another ride and laided the coal to her I made acouple hard pull runs with some cool downs speeds and the noise is still there and it's not getting louder. I have a full tank of fuel ran through the new top end now. It's been 3 months since the last time I rode her but I do not remember this sound. It seems to be at idle only and after I idle back down from a high speed run. Do I need a new copper crush washer at the pipe Or am I smoking crack and this is normal because I tried to kill her but she ran strong. What do ya'll think

[hughes]

Just read jdv500 post about engine noise up front (rattle). New o-rings and copper washer fixed his noise. My o-rings are new and springs are good and tight. Copper washer is smashed. What is causing this noise when the copper washer is missing or worn

[mikesmith]

The o-rings and washer make a tight seal so the pipe doesnt rattle,and use high temp silicone on the o-rings where they slide into the cylinder.

[reknelb]

Be sure it isnt something totally unrelated to the engine. I had some rattling and it was my clutch lever bouncing off my plastic hand gaurd. What kind of piston to cylinder clearence are you running?

[hughes]

I do use high temp silcone but this crush washer is about 8 months old and I have had the pipe off 4-5 times. Piston to cylinder wall clearence is unknow. My cylinder looked good so I installed new top end. I know that is not the correct way. This rattle is only at idle. I am going to get some new copper pipe washers because mine is smashed and cracking. I have two tank of fuel ran through her now.

[hughes]

New 0-rings, New springs, new washer and rattle is still there. I have checked everything to make sure it isn't somthing unrelated. This rattle is at idle only right at the the cylinder area. When installing my power vavles my manuals say lube them with moly lube I had to use white lithum grease. Would this cause these valves to rattle I ran right at 3 tanks of fuel through her this past sat. That makes about 6 tanks ran through her with no problems. I have checked the cylinder and piston through the pipe area four times after riding everything looks good. The noise is high in the cylinder not in the crank case. Any help. Thanks

[hoopty]

Does it sound like a can of marbles?

[teamgreen500]

It may be a harmonic effect created by all the moving parts in the motor.

Make sure you're not hearing the clutch basket or something-else resonating. Does it do this when you pull the clutch in?

Even the trannies can be noisy.

[hughes]

I guess you could say it sounds like a can of mables. Yes, still rattles with clutch pulled in. Maybe it's nothing to worry about because she running strong with no signs of the noise getting louder. I just don't remmber this sound until I replaced the top end. This bike is an 87 500 the piston had a single ring I installed 88 or new kit where the piston has two rings. Could the sound be from the second ring (wild guess)

[ebers17]

Hey, I just changed my pipe, from a stock one to a fmf burly pipe.  When i had the stock pipe on, it wasn't sealed properly, and i never noticed the knocking noise.  Now, with my burly pipe on, i sealed it up with the high temp rtv cement stuff.  I started it up, and i hear a knocking noise like i've never heard before, its coming from the cyclinder it sounds like, possibly bottom end?  I ran it a little bit and it ran fine, so i even did a hare scramble today at it ran great, so i dont know what to look at.  Did it do something when i sealed it up? - Seth


-reknelb, shouldve went to jasper today! it was a blast of track, alot of open field and some tight trails!

[hughes]

After I installed a pipe guard the noise is almost gone. I guess the extra weight on the pipe is keeping it from vibrating. I am just going to use it. I have new springs and 0-ring sealed with silicone.

[martinfan30]

OLD THREAD ALERT!!!

I have this noise too. Very loud at idle. I can hear it in the house. I have the bash plate off right now, and will put it back on later and retry.

Top end just done, all new o rings, piston, re plate, reed block (v2). Seems like this may be a common thing on these bikes?

[martinfan30]

The noise seemed to change a little with the bash plate on, but still loud. It goes with RPM up to about 2000, then you cant hear it.

[Johnniespeed]

Every time that noise happens in my bike ( 04KX500 ) the exhaust mounts are the culprit and I find one or more is broken. I keep several in my tool box. Another  noise I have heard is from the kicker hitting the Gnarley pipe.
 Hope you find the cause of your noise easily.
 John

[martinfan30]

The mount at the top bend of the pipe is busted. I wired it together, but not sure if its good enough.