RM250Rida

Member
May 16, 2001
31
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OK, maybe you guys remmber the problem I was having before with the knocking sound. I thought it was form the low octane (89) gas that I was using so I started buying 93. First I tried Coastal's 93 octane. The bike ran a lot better but I still had the knock. The hext time I needed some more gas I got some 93 at a Dandy Mini Mart. Again the bike ran better, even better then it did on coastal, but the knock was still there. I just got done rebuilding my top end and borrowed a little gas from a friend. He mixes the same, uses the same oil but I think his gas is either 93 or 94 that contains oxidants which he buys from Agway. Not sure about where its from but pretty sure it's Agway. I figured the knock was from carbon build up so I thought it;d be gone after I rebuilt it. But tonight after I got it rebuilt and was working on braking it in, I still heard the knock occasionally. It's mainly when I just close the throttle completely from having it anywhere's above 1/2 throttle. I thought maybe the pilot was lean and when I let off and the pilot takes over it wasn;t supplying enough fuel. I played around with the pilot air screw making it richer. The knocks still there and when I let off the throttle a puff of smoke comes out the back so I dont really think it's lean but maybe. I'm begining to think that it may be the power valve slamming shut. I notice when I had the top end apart that if I worked the little lever arm that controls the power valve it will knock if I let right off it and let it shut on it's own. Will it still do that with the engine running? Is there a way to adjust the tension on it so it doesn't slam shut that hard? Or dont you guys think thats the problem?
 

Brian

Stanbagger
N. Texas SP
LIFETIME SPONSOR
May 1, 2001
1,452
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I have this same problem with my KDX, and am stumped? Anyone :think:
 

JTurn36178

~SPONSOR~
May 17, 2002
131
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Is this knock on deceleration only?

When the motor is being pushed by the wheel with the throttle shut?

If that is the situation, then it may sound more like a cluk.

What do you other guys think?
 

Brian

Stanbagger
N. Texas SP
LIFETIME SPONSOR
May 1, 2001
1,452
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Yes, it's under decelleration only, and id definatly a ping/knock.
 

nikki

Moto Junkie
Apr 21, 2000
5,802
1
If the knocking is kind of like a "pinging" noise near the cylinder and on deceleration and you hear it going into a corner when you let off of the gas - it is possible that it's about time for a bottom end. If the bottom end bearing and/or rod is getting worn - the slop will cause this noise. RM250Rida - did you check the play in your rod when you did the new top end?
 

Brian

Stanbagger
N. Texas SP
LIFETIME SPONSOR
May 1, 2001
1,452
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Nikki, this sounds like it may be the ticket, will tear it down soon and inspect it. :)
 
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