99 YZ400, intermittent grabby clutch


9 replies to this topic
  • ochsnera

Posted April 27, 2007 - 07:01 AM

#1

Sometimes it's perfect and other times it will lurch. Seems random. Sometimes it will lurch and I'll stop and relaunch and it will pull smoothly. Likewise I might launch smooth and a minute later it will lurch.

I'm not much of a mechanic but could someone tell me what the possible causes for this might be? Anything inperticular I should look at?

Thanks

  • 426_kid

Posted April 27, 2007 - 09:07 AM

#2

if its imtermitten it may be the oil? or something to that effect. I could be wrong though.

  • ochsnera

Posted April 27, 2007 - 11:05 AM

#3

I'm running Valvoline 4stroke 20-50. It's been run in my KLR650 and FZ1 for about a year now without any problems.

Should take the clutch out and check it out but I honestly wouldn't know a good clutch from a worn one.

  • CaptainKnobby

Posted April 27, 2007 - 11:31 AM

#4

Sometimes it's perfect and other times it will lurch. Seems random. Sometimes it will lurch and I'll stop and relaunch and it will pull smoothly. Likewise I might launch smooth and a minute later it will lurch.

I'm not much of a mechanic but could someone tell me what the possible causes for this might be? Anything inperticular I should look at?

Thanks

You might want to take the cover off the side and check the clutch basket.....Could be possible the basket has notches cut out on it.>>> In other words the clutche plates and friction plates has fingers or flanges on the ends of them and when the bike is in gear and the clutch is engaged when you realease the clutch lever those fingers on the ends of the plates catches on the basket and after long time use those fingers cut in the basket and causes the notches in the basket to ware and get wider thus given you that lurch feeling.:applause:

  • rbinstoon

Posted April 27, 2007 - 11:36 AM

#5

You should probably pull out the clutch plates and and springs to check them, if the plates are worn down or the springs have lost some of their free length you could lose some of the clamping force from the springs and the clutch may not grab and lock smoothly. The specs for the thickness of the plates and length of the springs is in the manual, but to check the plates properly you should use a caliper.

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  • DrThumper

Posted April 27, 2007 - 12:04 PM

#6

You got an oil issue. You probably used an oil w/ "Energy Conservation Additives". It ruins clutches. I had the same problem years ago. Check the back of the oil container and look for that little white circle, if it says "Energy Conserving" in the bottom half, thats the culprit.

You'll most likely have to replace the fiber plates. Might as well do the '01 clutch mod while your at it (if a you can on a 99, you can on a 2000). It makes the clutch work soooo much better. Do a search on TT for the mod. You'll have to buy a couple internal parts like the push rod, and one of the plates is different...as I recall, its been awhile. It was one of the best mods I ever did.

  • rbinstoon

Posted April 27, 2007 - 12:44 PM

#7

[quote name='DrThumper']You got an oil issue. You probably used an oil w/ "Energy Conservation Additives". It ruins clutches. I had the same problem years ago. Check the back of the oil container and look for that little white circle, if it says "Energy Conserving" in the bottom half, thats the culprit.QUOTE]

He stated that he was using Valvoline 4-stroke 20-50, though, which says it is intended for wet clutches. It wouldn't be the energy conserving oil you are talking about, would it?

  • 426_kid

Posted April 27, 2007 - 01:07 PM

#8

those energy conserving things can creep up on you with out knowin... there sneaky:foul: people...lol so I think i was right in the beginning... OIL...:applause:

before you pull it apart it might be cheaper jus to try a new oil with out that energy conservation stuff and see if that'll fix it... its cheaper and easier that pullin the clutch out , especially if it works:thumbsup:

  • rbinstoon

Posted April 27, 2007 - 02:29 PM

#9

How would changing the oil be cheaper? You don't need to drain the oil to check the clutch so there is no cost involved, it just takes a little longer.

The Valvoline 4-stroke 20-50 oil is certified to JASO-MA which means it is for motorcycles and is without the friction modifiers (ie. molybdenum, which damages the clutch plates) and it is not the energy conserving type - those are the lower viscosity types because higher viscosity means more HP robbed.

  • ochsnera

Posted May 01, 2007 - 12:11 PM

#10

Thanks for the many replies. I'm going to take it down and check out the clutch. Would anyone know of a picture of a basket w/ notches vs a healthy one? Don't have a service manual yet, it's ordred, and would like to take it apart tonight.





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