This problem is blowing my mind.

streaks383

streaks383

PR Addict
I have a 2005 yz-250, eric gorr 295 kit, bike has been a dream until today. Now it has a surging thing going on rather a miss is happening, not a miss in the engine but a miss in the drive train somewhere but it is only in 5th gear and it is very consistent, it happens like clock work at constant intervals regardless of RPM or throttle position? The best way to describe the feeling is if you were to go at a constant rpm in 5th gear and were to fan the clutch. Any ideas?
 
my guess would be in the carb, but due to different throttle positions that sounds very strange. needs more gas at higher rpms, so I would start there. could be a small blockage in fuel line or a jet stuck possibly. I'm definately no expert, so good luck to you.
 
You mentioned the clutch so I assume you've already been looking at it, but certainly in 5th gear you are putting the highest torque (relative to rear tire load) though the clutch. I think, if you haven't already I'd focus all my attention there (maybe add a plate to the stack and see what happens).
 
When was the last time it had a fresh clutch pack? Sound like the clutch could be slipping. Or as pit stated my next guess would be the tranny.
 
Elliot, I have ruled out the carb because it only happens in 5th gear, does this sound logical to you, I'm not expert on carbs.

Pit, Thats what I was thinking but hoping I was wrong.

Kremm, I pulled the clutch apart last night, all the plates are in spec and look pretty good, so I cleaned the plates and steels and soaked them in new oil last night, its behavior is not typical for a clutch slipping. In my experiences they either slip or they don't , but I am hoping it is a clutch I don't want to be splitting the cases.
 
It sounds like maybe the drive dogs on either 3[SUP]rd[/SUP] or 4[SUP]th[/SUP] gear have started to round a little allowing 5[SUP]th[/SUP] to slip out.
A bent shifter fork or worn shift drum can cause the same thing to happen.....not fully engaging 5[SUP]th[/SUP].<O:p</O:p
…Oh, Last night I finally got to wring-out my Eric Gorr YZ -300 against a Kaw 450 on some nice up-hill practice starts…It Rips!!!!
 
Thanks Marc, I guess now I get to split the cases and try to figure out what is going on. And yeah, they do some pulling!
 
Ride your bike slow and put it in high gear (4th or 5th) and get on the throttle hard,if it slips its the clutch if not it the transmission. I think Sharc is on the right track,it sounds the dogs are worn and making it slip...
 
Without actually riding the bike, it sure sounds like the tranny, usually it would be 3rd or sometimes 4th gear !
I have split hundreds of them, if You are solving a tranny problem Do NOT cut a corner Or overlook even the slightest detail or You WILL get to split them again !
 
Cases split and taken in to Action, they will tell me what I messed up and then I can replace it (them) Thanks for all of the tips guys.
 
I have to tear into mine as well.....
Yesterday at the Cliff she's locked in top gear and the shifter is rigid.


.....let us know what the deal was.....
 
Got this post mixed in my head with the honda one in here...sorry! That sucks about the YZ though.....
 
Streaks and Marc,
I see the issue now, obviously the common denominator is that Eric Gore big bore kit. Just send me your kit, and I'll send you back my stock parts. Problem Solved!
 
kremm140 said:
Streaks and Marc,
I see the issue now, obviously the common denominator is that Eric Gore big bore kit. Just send me your kit, and I'll send you back my stock parts. Problem Solved!
Click to expand...

Maybe we are overpowering the transmission? I wonder if anyone else has had this problem
 
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