mystery noise

[matzilla]

Ok, I have this mystery noise at low idle. Sounds like a big vibration rattle. If I bump the throttle slightly it disappears. Sounds like it comes from the top end area, maybe the exhaust header or something. Really annoying and concerning. Has done it since we put it back together. My friend had originally said it could be due to wiseco's .004 recommendation for piston skirt clearance. Engine is 0.5mm over bore, stock stroke, all new bearings and seals, PC pipe, V force reeds, bored carb,  running 110 octane gas, 40:1 with dumonde tech oil. 60 pilot, 180 main, CEJ needle 3rd from the top. It runs a little rich, but not fouling plugs. - am constantly checking bolts and am wanting to figure this out. Any thoughts?

[Larry Wiechman]

 Center KIPS valve flutter. The 4mm pins rattle in the spiral grooves on the barrel valves. You made the mistake of cleaning it up so nice and pretty when you rebuilt?
 Thats my story, and I'm stick'n to it.
 
Larry

[demographic]

Mine does the same and as all the bearings are new, the pistons fresh all I could think of was the centre KIPS valve, makes quite a clattering noise though doesn't it?

[DoldGuy]

Could it be the Pipe Retaining Springs? These will cause some annoying rattle. I usually run a piece of fuel line over the length of the spring & leave just enough of the hook exposed to grab with a spring hook to install & this dampens just about all of their noise.

Just something to consider.

DoldGuy

[BDI]

It's the kips valve. The blast of exhaust gasses pushes up on the center valve and lifts the whole valve up including the two vertical valves that ride on the cases. The are definitely louder when they are freshly cleaned but there are several things that help to make them louder.The noise comes from the vertical valves crashing back down on the cases after each cycle. You can dampen this sound based on the type of base gasket you use. The stock gasket has big holes under the valves so it's all metal to metal and allows there to be a lot of play in the valve but if you make or order gaskets with the small holes it will dampen the sound do to the gasket material separating the metal to metal contact.It will also tighten up the extra play in the valves by pushing up on the aluminum plugs that hold the valves in place. My bike has two metal base gaskets with an aluminum spacer and it is super loud. Hope this helps.

[matzilla]

Thank you all so much for the speedy replies. That makes me feel lots better. I'm glad to know that noise isn't a future catastrophy waiting to happen.

[Polar-Bus]

Check the copper exhaust gasket between the pipe and the cyl. Also check the condition of the two exhaust pipe o-rings. If these parts get worn, your exhaust pipe will vibrate and hammer the pi$$ out of your cylinder. I actually run 2 copper exhaust gaskets to keep the vibration to a minimum.

[BDI]

Thank you all so much for the speedy replies. That makes me feel lots better. I'm glad to know that noise isn't a future catastrophy waiting to happen.

What are you running for a base gasket/

[matzilla]

Just the stock/standard base gasket. It has the big holes under the valves. And I super cleaned everything when it was apart. Makes sense now when I think about the noise. Before when I heard it, I thought it was a possible cause but was unsure. Thanks again to all.

[Larry Wiechman]

 Just ride the wheels off that thing!  A nice, fresh coating of carbon and oily mung will quiet that rattle soon.
 
Larry

[streetsweeper]

copper gasket pounded down paper thin and split in two is it necessry to replace with 2?  also visually inspecting pipe o rings what would be considered worn pst service limit?  any feedback would be nice.  thanks ss

[stewart]

i would get the copper gasket new from factory kaw and some of the orings i have seen in kits are not thick enough also som times the pipe springs are not tight or on wrong and cause niose

[streetsweeper]

Thanks for the confirmation , I installed the copper gasket with lip facing piston and round side facing outward.  Would not stay in place so i used a little exhuast aqustic sealant to get it to stick in place.

My concern is I also applied a thin coat of that stuff on and around the o ring area, hope it doesnt harden the o rings.

I had ordered two copper gaskets, two orings and three springs last week, just wasnt sure if installing two gaskets was going to improve overall life or performance.
 
anyways just hope it works out with that exuast aqustic sealant i got from napa

I will take it out after work this week for a few jaunts and see if that mystry noise goes away.    Thanks for your feedbak Stewart   ...ss...

[kaw rider]

Doug is this the thread.