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Powerbandmx

2007 YZ450F clutch issue

8 posts in this topic

Hey, I was wondering if anyone out there is having the same problem as me and if anyone knows of any remedies for this problem.

I have a highly modified 2007 YZ450F (HC piston, cams, ignition, pipe, etc) and I cannot keep a clutch in it. I am aware of the pro circuit stiffer springs which are available, which I have already ordered to help the problem. However, the weird thing about this whole issue is that I never had clutch issues with my 2006 YZ450F. I went the entire season on 2 sets of clutches, but last year I needed a clutch every two races and I am anticipating the same problem for this year.

I know from 2006-2007 they went from 9 fibers and 8 steels to 8 fibers and 7 steels and they also changed the pressure plate and hub to accommodate this difference. I have heard of guys actually having their hubs machined to help the 2007 clutch because the problem seems to be that when the clutch gets hot, the hub expands, causing the gap between the pressure plate and the outer most friction to get bigger. This results in not enough pressure being applied to the plates which causes the clutch to begin slipping. This quickly results in a fried clutch. The mod that I heard of a couple guys doing basically decreases the gap between the pressure plate and the friction, resulting in more pressure applied to the plates, even once they become a bit worn.

Has anyone heard of this mod and its validity or any other mods that might help? Should I just go to a Rekluse clutch or will I have just as many problems...? Does anyone have the answer??

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In the first place, the clutch boss (hub) is the same part in both the '06 and '07. The difference in the stack height of the clutch was made up for in the thickness of the steel plates, and I believe the change to the pressure plate was to make it stiffer. The springs were also changed.

You can cure your problem by going to an '06 plate set (Hinson prefers this), and perhaps help more by upgrading to either GYT-R or Hinson plates. Use the '06 springs when you do this. When you get the clutch in place and adjusted, remove the plates and put the pressure plate back on with the springs run down only lightly and check how it fits/meshes/clears the boss, just to be sure

Also, if I may say so, there is very little reason to be that hard on the clutch in a big 4-stroke, and you may want to look into altering whatever it is you are doing to the thing. The bike has a transmission and a power band that is about 5-6000 rpm wide. I have no idea as to why slipping the clutch should be that necessary. But enough of that. The '06 setup should get you back where you were.

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Ok, so if I were to go to yamaha and order some parts, what would I tell them I need? I'm having the same clutch problem. I replaced mine 3/4 of the way through the season last year and I feel that I need another one now. When I replaced it, I didn't replace the metal plates, just the fiber ones (or whatever they are called). So I need to order the metal plates and the other plates for an 06 and get the springs?

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Yes, the complete set of clutch plates for an '06, and the clutch springs to go with it.

One other thing will need to be checked: The depth of the spring pocket may be different in the pressure plates of the two models, and depending on what the difference is, the spring pressure could be too light or too heavy. The '06 normally has just a little heavier pull than the '07. See how it sets up. If it just feels wrong, try your original springs. You could end up with an '06 pressure plate as well. Maybe someone else who has installed the '06 plates in an '07 can clear up this detail.

Another option that may not be much more expensive is the GYT-R clutch kit for the '06.

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If I stayed with the 07 setup. Should I change out the metal plates or just putting in new fiber discs going to be fine? I think one more clutch will last me the rest of the year and then I'm going to sell the bike.

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Grayracer513

-Are the clutch components the same from 07-08? Just curious if this might be an issue for the 08 YZ450F.

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