Power "Slips" While Under Load - Clutch???

7 replies to this topic
  • yz_for_me

Posted November 20, 2007 - 11:00 PM


I took the bike out for a few laps on the track the other day and noticed something I haven't before. A couple times while accelerating hard I could feel the power "slip" for the lack of a better way to describe it. It was like a small but abrupt hesitation that you could feel more than anything and did not make any noise when it happened. It was a very quick anomaly and only happened a couple times.

Also, this may or may not be related, but when I quit I could smell burnt oil. I could not see any obvious leaks but I could definitely smell it.

My first intuition is the clutch. The bike is an '03 with about 70 hours on it, so I'm thinking the clutch is a likely suspect. I'm running a Rekluse with the original basket and fiber plates. Does this sound like a reasonable place to start considering the symptoms I've described? I haven't had time yet to do any investigating (and won't for a while - hanging drywall in my basement), but any suggestions what to look for would be appreciated.

  • grayracer513

Posted November 20, 2007 - 11:17 PM


You said it feels abrupt. I assume then that "jerky" would describe it? Important question: Does it do this only in one gear?

  • yz_for_me

Posted November 20, 2007 - 11:46 PM


Jerky would be a good word, but it would only be one "jerk" each time it happened.

The only gear I noticed it in was third, but on my track I'm in third 90% of the time so that may not mean anything. I thought of that too, but I think I would have to do more testing to really answer that question. Without more information, I suppose third would be the one to look at first.

Another thought I had. Could I be loosing spark for a split second? Would that cause what I'm feeling? It wouldn't account for the burnt oil smell though if it's related.

  • grayracer513

Posted November 21, 2007 - 07:48 AM


Do some more checking. If it's a clutch issue, it wouldn't be an abrupt jerk, it would be more like the tire slipping, except internal. It would also be worse in 4th than 3rd. A spark problem is possible but less likely, since to jerk that hard, it would need to essentially turn off for several cycles in a row, and would be very prone to producing a loud pop as it came back on and fired the fuel in the exhaust.

What this sounds most like is worn locking lugs on the 3rd wheel gear (on the output shaft) and on the 4th wheel gear that locks it to the shaft when it's engaged. The shift fork will also be damaged. The lugs are built with a slight under cut to hold in gear under a load. when they wear, they round over the other way, and the gears force themselves apart under a load against the shift fork instead. The fork then slams them back together, and the whole thing produces the jerk you describe.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • yz_for_me

Posted November 22, 2007 - 09:36 PM


Thanks gray. I'll dig into it one of these days. Not much good riding weather for a while anyway.

  • buzzgrizz

Posted November 23, 2007 - 04:26 PM


Could it be the type oil your useing. Some car oils cause clutches to slip.

  • yz_for_me

Posted November 25, 2007 - 11:06 PM


Could it be the type oil your useing. Some car oils cause clutches to slip.

I don't think so. I'm using the Shell Rotella T. I've been using it for a while and haven't noticed this before.

  • mj2412

Posted November 26, 2007 - 02:17 AM


Hello, sounds like the transmission. I had the same at the beginning of the summer. First thought was also the clutch, and the springs were bad, but after changing the clutch springs it became worse and then i checked the transmission. Third gear wasn't good anymore. Unfortunatly you have to change the next gear also. In the end i checked everything and changed 7 gears and on shifting fork.

Related Content


Is it worth it? (Cam and High compression piston) by macgi77

Dirt Bike   Make / Model Specific   Honda   CRF 150/230 F/L
  • Hot  36 replies

100 hrs on 2014 yz450f, shim valves or replace them? by ttr230rider6

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • Hot  79 replies

Thinking about Yamaha 250... by Arctic Pride

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  491 replies

Need help by Goforaride

Dirt Bike   Dirt Bike Technical Forums   Suspension
  • Hot  68 replies

YZ450F 03 Sparks driving me crazy by SirAttard

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 5 replies

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.