Motor noise need help.

prozach
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prozach
Edited Date/Time 8/23/2015 7:05pm
Been riding for 30 years never seen anything like this. The bike was running fine. Made a hissing noise in a turn, I stopped and it went away. Thought it was mud or something in the chain. Rode a few more laps and it did it again but worse, then went away. Came back to the truck and it got worse but still intermentant. In the video the
bike is in nutural and when the noise starts the bike lurches forward! The clutch and valve clearance appear to be fine. Any ideas?
https://youtu.be/x5YTLN9_-7s
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prozach
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prozach 8/23/2015 12:11pm
8/23/2015 12:11pm
Thanks, try again. I think I made it public.
SouthwestMfg
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SouthwestMfg 8/23/2015 12:24pm
8/23/2015 12:24pm
That's not a hiss. Bearing or bushing somewhere. Kind of a high-speed shake / oscillation. Find the area where the noise is coming from and start digging in there. (it's not the valve clearance).
The Rock
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The Rock 8/23/2015 12:38pm
8/23/2015 12:38pm
How many hours? Did you put the bike in gear to get it to make that noise?

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prozach
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prozach 8/23/2015 1:05pm
8/23/2015 1:05pm
Thanks, for the input. I' m thinking a bearing in the transmission. I don't see how else it could move forward like that when in nutural. About 60 hrs on the bike, it has had a top end. I'm vet pro speed. Not usually overlly hard on stuff though.
BobPA
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BobPA 8/23/2015 1:14pm
8/23/2015 1:14pm
How can you spin a roller bearing?

But it does sound like a bearing issue to me. Pull your clutch cover off and check the main shaft for play.

jtiger12
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jtiger12 8/23/2015 1:20pm
8/23/2015 1:20pm
I'll second the bearing issue idea, that's what I was thinking . Kickstart bushing would be my first check
hillbilly
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hillbilly 8/23/2015 2:35pm
8/23/2015 2:35pm
When you drain the tranny oil you should see debri.

It could be a few things. Worn shift fork letting the gear try to dog in or the fork is bent.

The bearings on the end of each tranny shaft are sheilded,meaning they are back in the case with a tiny hole that lets oil get to the back side.,if it fails the shaft end has play and lets gears touch and will cause the lurch.

And,it could be a gear gaulding on the shaft and making it lurch. Some have rollers some just a bushing.

The big bearings usually dont fail unless the chain has been run tight and the countershaft bearing is killed.

Cases will have to be split.
jloucks742
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jloucks742 8/23/2015 2:48pm
8/23/2015 2:48pm
My first guess would be to pull the clutch apart and check everything. If its something in there atleast it will be somewhat cheap
hillbilly
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hillbilly 8/23/2015 3:01pm
8/23/2015 3:01pm
The clutch or starter idle gear would not make the bike lurch when in neutral.

It is tying up between the tranny shafts in some way.

They are either not parallel from a bad bearing,a bad gear bearing or the shift forks are letting gears touch.
blusmbl
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blusmbl 8/23/2015 3:42pm
8/23/2015 3:42pm
hillbilly wrote:
The clutch or starter idle gear would not make the bike lurch when in neutral. It is tying up between the tranny shafts in some way...
The clutch or starter idle gear would not make the bike lurch when in neutral.

It is tying up between the tranny shafts in some way.

They are either not parallel from a bad bearing,a bad gear bearing or the shift forks are letting gears touch.
x2. No fixing that one without splitting the cases.
dosparks
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dosparks 8/23/2015 3:53pm
8/23/2015 3:53pm
I haven't personally experienced it, but that sounds like the common clutch pushrod issue the KX 450's were experiencing. Go to thumpertalk and search the KX450 forum and there is a walkthru detailing the fix. If I recall correctly it was pretty simple, maybe just grinding the end of the clutch pushrod down. I would definitely give that a shot before splitting the cases. I don't have time to search right now to give you a direct link but let me know if you have any trouble finding it.
hillbilly
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hillbilly 8/23/2015 7:05pm
8/23/2015 7:05pm
dosparks wrote:
I haven't personally experienced it, but that sounds like the common clutch pushrod issue the KX 450's were experiencing. Go to thumpertalk and search the KX450...
I haven't personally experienced it, but that sounds like the common clutch pushrod issue the KX 450's were experiencing. Go to thumpertalk and search the KX450 forum and there is a walkthru detailing the fix. If I recall correctly it was pretty simple, maybe just grinding the end of the clutch pushrod down. I would definitely give that a shot before splitting the cases. I don't have time to search right now to give you a direct link but let me know if you have any trouble finding it.
The pushrod wouldn't make it lurch,its messing between the primary shaft and secondary shaft.

A gaulded bushing would be my guess,shift fork if it fell on that side hard .

A problem with the clutch would not make it lurch while in the neutral notch.

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