Knocking sound in idle...

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MitchP

MitchP

New Member
Oct 6, 2012
276
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Santa Rosa, CA
I was cruising this morning at a little over 20mph when my bike got louder. Louder in pitch to be specific. When I had the bike at a lower speed I heard knocking, like a jackhammer (not as loud but my ears are ringing) or two pieces of wood being clapped together. In idle this noise was especially prevalent. Last night I tightened the head and spark plug a little. Is the piston knocking on the head or something?? Sounds like the piston and increases with RPM's.

Edit: using good oil and 91 octane. Also tightened a few things in the clutch.
This was my last post in my clutch problems thread:

"Well the flat head screw on the smaller gear behind the clutch cover on the right side (if you were standing over it on your bike) was all the way backed out. Runs much better now lol."

http://motorbicycling.com/showthread.php?t=47057
 
Last edited:
Huffydavidson

Huffydavidson

STREETRACER/MANUFACTURER
Jan 29, 2012
1,076
4
38
st.louis,mo.
Hey Mitch, before you go and take the top apart, do this FIRST. #1) Remove the plug. #2) Remove your Speedemond exhaust. #4) DesKinect the clutch cable from the clutch actuator arm . #5) Remove clutch actuator and bucking bar, and plug the hole with some paper towel leaving enough out so you can pull it back out with your fingers .this will keep you from losing the ball bearing . #6) Take a flashlight looking exhaust port see if the piston is down. #7). take your ratchet 19 millimeter socket and put it on the drive wheel. carefully sticking your finger in exhaust for with the piston down ,turn your ratchet to see just a little bit to see if the piston stay still for a second there should be no play if you turn and the stays like there slack then tear it down and call me I'll walk you threw it.
 
MitchP

MitchP

New Member
Oct 6, 2012
276
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Santa Rosa, CA
My conclusion is that it was 4 stroking due to badly matched ports and developed a knock. This motor is now being used as tester of sorts. My next motor is an F80, port polished, will be port matched, RT carb, Manic Mechanic intake and good gaskets. Between bad matching, The retarded intake that comes on CNS carbs (I was running an NT) and all my WOT adventures it got a knock. Really it sounded like a jackhammer hitting cement.

Does it harm anything to turn the slant-stlye head forward to have the spark plug closer to the CDI?
 
MitchP

MitchP

New Member
Oct 6, 2012
276
0
0
Santa Rosa, CA
Oh I mean if the CDI is on the bottom tube instead of the front tube but after seeing pictures I'll probably keep it on the seat tube for a cleaner look.
 
CTripps

CTripps

Active Member
Aug 22, 2011
1,310
1
38
Vancouver, B.C.
As far as I can tell, it doesn't reall matter which way the head 'faces', it should torque down the same. It's just less practical to have the plug going sideways.
 
crassius

crassius

Well-Known Member
Sep 30, 2012
4,032
158
63
USA
most of the time those are not interchangeable since they are usually on diff sized motors with diff sized head studs
 
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