Clutch problems

Sorry this is off topic, do you have the white backgrounds flu team graphics? If so do you have any more pictures of the bike with them? 

Don't know what flu team is



So you are saying the plates are sticking together because there is not enough oil flow, even though everytime you pull in the clutch, all the plates are bathed in oil?


...and you've proven this by starting it in gear in your garage?


If that were the case, holding the clutch in for a while, getting plenty of oil on everything, then putting it in gear, it should not drag......but it does.

The metals do not hold anything but a microsopic film of oil. Adding more won't stick.


The washers have nothing to do with coil binding.

It's about allowing the plates to be engaged with with less force, so they don't grip each other as tightly, and can move more freely, sooner, when you pull the clutch in.

THAT is the problem, They ARE NOT bathed in oil very well. The six small holes are not spaced evenly through out the clutch pack. They are evenly spaced radially but not along the axis. As mentioned there are not even any holes behind any of the first three to four clutch plates.  The holes that are in the clutch boss are not big enough to allow enough oil to circulate all though the clutch pack. ESPECIALLY when the clutch is pulled in as this allows a lot more area for the oil to sling out between the plates once the clutch is pulled and the plates separate. When they do separate what oil that is there does not make it out to those 3-4 outermost plates at all, before more holes are added. This also explains why when I added the three holes out closer to the edge of the boss the change in the bike NOT pulling forward while in gear, was so noticeable.


 YES I have proven it in my garage. Before all the holes were added, when I put it in gear, it took BOTH feet on the ground, or brakes applied to keep it from pulling forward. I can now put it in gear with absolutely no forward pull as well as easily back it up while running and in gear with just one foot. The BIG tell tale sign however is how EASILY it now starts while in gear. This "feat" was impossible prior to adding more holes and was my biggest issue........Could not get the motor to relight while in gear. 


  The oil supply going into the cutch boss is limited or metered by the flange interface on the backside of the clutch boss and the way it fits up against the inner case, NOT by the amount of outlet holes in the boss. Adding holes in the boss will not change the oil supply to the head.


 Also by filing the casting flash off the inlet holes and ever so slightly bell mouthing them it should allow a little more oil into the boss. Especially as the boss/case interface on the back side of the boss is designed to "leak" excess oil out all around the clutch boss as it also pushes through the inlet holes.  I am pretty certain that boss gets filled with oil fairly full when running. Once the clutch is pulled in and the plates separate it takes a real good supply, AND more evenly spaced holes to keep the oil enenly distributed all through the clutch pack as it flings out under centrifugal force. Before addition of more holes no oil was making it out to the 3-4 outermost clutch discs when the clutch was pulled in as it flings out between the clutch discs radially before it can get out to them, so if no holes are located behind some of the clutch discs the oil never gets to those plates once the plates are separated.


 I believe the problem was twofold. First the lack of holes out behind the outermost clutch plates caused added drag due to those plates being under oiled all the time, and then due to to small and to few holes in the boss an undersupply of oil to the area of the plates between the existing holes in the clutch pack, especially when it is disengaged as the oil that is present is not sufficient to adequately keep all the plates bathed in oil as it was finding its way out of the clutch pack due to an undersupply.


 I agree that the washers have NOTHING to do with coil bind .All they do is keep you from compressing the springs down to that 1.130 dimension I measured. If washers are installed the spring will only compress down to 1.190. Thing is, clutch springs have the same rate of compression all through their useable range, they do not get stronger or harder to compress as they get compressed more (unless they are a progressive springs, like fork springs so this will not make it easier to pull in the clutch, just keeps you from pulling them down closer to their fully compressed state, which by my measurements cannot be reached with the existing lever range in the clutch actuation.

Yamaha clutches disengage about .110, and that is the problem

So every little bit helps.


I think the best thing would be to change the actuator cam profile on the throwout rod. That would change everything. 


You first....

 I looked into that as well. Weird in that the clutch actuation rod for the '03 WR's is unique to this bike. Several YZ and WR's use the same part number actuator for some years but NOT this one.......lucky me!.......not sure what the difference is but I got one of each coming (YZ and WR for '03) off ebay so will let you know what I find there! 

Don't know what flu team is



Oh the bike you had pictures of on your thread, Is your clutch a drag?, It looked like these coolgraphics_zps826b2651.jpg

I went out today and logged 43 miles. Unbelievable! It is like a completely new or different machine. The clutch engagement is smooth as pre softened margarine! It is an eye opener to once again ride a bike with a perfectly functioning clutch. Since I have been riding nothing in the dirt but this bike all Summer with a funky clutch I forgot how much a good clutch makes it so much easier to ride in the knarly stuff. This clutch now responds real well when I feather it, especially on real rocky or steep grass covered hills, even early in the AM when there was dew on the grass. Takeoffs headed uphill are much, MUCH smoother as I can now feel the clutch as it engages a LOT better and it is real easy to feel it feather in and out now. Even in an area where there was a lot of real light pumice rock, which is REAL easy to bury a rear tire into I can now feel the clutch engagement through the lever WAY better!  


 I also now realize the clutch was pretty grabby before the hole modifications. I had not really noticed this till this morning when it was no longer there. I believe this was due to it seeming to have a pretty short engagement throw before the addition of more oil holes. Once it started to engage before I added more, you only let off maybe another 1/8th to 3/16ths of an inch and it was locked it seems to have maybe 1/2 inch of engagement throw and a LOT better feedback/feel in the lever as well.


 Another thing I have been missing all Summer is when coasting downhill I USED to leave it in a lower gear, use engine braking on the rear wheel and then apply the front brake to slow or hold speed down. I like that technique and used it quite often on other bikes but had to give it up as before the clutch mods this was causing the motor to die which I had never experienced before, and did not like at all. In the rain a few weeks back it was happening so bad I had to raise the idle to keep the motor lit but could not use it for engine braking at all due to how high the idle needed to be set to keep the motor turning over.That is all gone now as I tried that a lot today and did not kill the motor once. Of course being able to feather the clutch properly helps with that as well. 


 Now that this is FINALLY cured I am going to have LOTS more time to ride! HA!

Well, I absolutely cannot see how this would help......but I do believe you achieved very good I will try it !


Could you please take everything apart again, and take pictures?


Thanks!  :rolleyes:

Good Lubrication is critical!


 I know I read about the WR250's and how lots of the owners were taking their clutches apart. They have a similar clutch issue. Their clutches have five rows of three holes in that inner boss. Probably a similar design (although I have not seen one in person or photos yet) and I beet it copies the 450's with the oil channel and outlet  holes being located in that channel.


 They are adding FIVE more rows of three holes each equally spaced between the existing rows. In fact I have a buddy who I found out yesterday just did this and he says it worked good.


 I have seen some pictures in ads for clutches and bosses from different clutch manufacturers and in those you can even see they have a BUNCH more oil outlet holes than these Yamahas come stock with. I think it was on a Barnet site that I first saw this but at the time it did not sink in. I made steady headway once I did start the drilling though. It was noticeable when I enlarged the existing holes , big gain when I added the three holes out in the boss where stock there were no holes, and then when I added the twelve new ones spaced so ALL the clutch plates saw a good flow of oil it was a remarkable improvement!


 I will try and take some pics....I do not have to disassemble as I got so dang many clutch parts for this scooter sitting all over my bench it is not funny!  Yesterday I received another boss I picked up off e bay as well as TWO different actuation rods as I was headed there next if the holes did not accomplish what I wanted.  


 AND all REALLY I wanted was for the thing to start easily with the button while in gear!

 I should have also mentioned that before you dissect anything to be sure and get a new fold over washer that locks the nut on inside the boss.


They are one use only and although not real pricey I hate to tear something down and get held up on re-assembly because of a lock washer.


 Rocky Mountain has them in stock, most dealers do not stock them and take a week to ten days to get them in. I usually receive stuff from Rocky Mountain in 3-4 days. 

Hope this works, never posted a pic here before. This 1st picture is of the inlet holes on the backside of the boss BEFORE I removed the burrs.



I have no idea how to add pictures, probably why I run machine tools and NOT computers.

'03 WR450 clutch 001.JPG

The second picture shows the same holes on a boss where I removed that burr/casting flash with a real small rat tail file and then slightly bell mouthed the opening of the hole. 


 That first picture of the latest boss I got off ebay is WAY more closed down and restricted than the first couple I opened up...I would like to talk to the guy whose bike it came off and see how his clutch worked! As previously stated you do not want to really enlarge these holes just remove the burrs and slightly file a chamfer or bell mouth shape on leading edge/start of hole to enhance oil flow.

Edited by ThumpMe

Try again.

'03 WR450 clutch 002.JPG

Cannot seem to post two pics in one reply. &%$#@!?


 This third pic shows the inside of the clutch boss and you can see the outlet holes in the bottom of the channel on the inner diameter. Inlet holes are on that back face.Also those inlet holes are not full diameter, They break out on a little lip so only HALF of the drill point breaks they are sort of half the diameter of the hole. this is probably what meters the oil into the clutch boss.


 You can also see in this shot how the outlet holes line up and go through located  in the center of the ribs on the outside of the boss.


Fourth pic shows the six holes I added in bottom of channel next to the rib that directs the oil on inside of boss. I tried to space them out for better flow so each one is located  a different distance out from the back surface.



Hopefully the fourth pic will show here?

'03 WR450 clutch 004.JPG

'03 WR450 clutch 003.JPG

Edited by ThumpMe

Those stock holes are kind of a joke on a few levels.


Any more holes?



I rode my WR on the nastiest silty/rutted hill single track today for 50+ miles, and the clutch works fine, but it still drags, cold or hot......

...mostly because of the stupid 'Heavy Duty' Tusk clutch pack I installed:

the metals are twice as thick as stock.... so when I get fed up with it and go back to stock or Barnett/Hinson, I will look at the basket.

Other than the ones in my!


 Actually I was having more issues as I do have a few more shots but I think I may have put to many posts up one after the other as it was doing some really weird stuff!

It seems that the holes did help in your situation but I am wondering if you are not just masking some other

problem with your clutch.   I have 9 WRs including 3 2003 models and while the clutches do drag they are nowhere

near the extreme that you described with yours.     It really sounds like your clutch was having an issue beyond

the "normal" WR450 clutch drag...


The WR250 crowd does a lot of clutch tinkering but those clutches are notorious for annoying amounts of drag,

usually noticeably worse than the WR450.

This shot shows what I was talking about a few posts back, well maybe more than a few!


 This sort of helps with  that explanation of where I added holes and how the numbers match up with the ribs. Stock outlet  holes break thru into the oil channels and line up with every fifth rib.You can see this on 1 and 6. 


 The boss in the bike now has had the stock six holes enlarged by .015. Went from .113 to .128


 Then three holes were added (.101 diameter) in three of the oil channels (every other oil channel) and located  in about .150 from that outer front edge. This gets some oil back behind the outer four plates....I looked at that today and it is two fiber and two steel plates that were not getting much/any oil in behind them.


 THEN what really made it work nice is I added twelve holes, through twelve different ribs located on the ribs between the stock holes. So those are located in ribs 3 and 4 and then that pattern is copied/repeated all the way around the outer diameter.


 They are all located slightly different in the axial plane to try and keep oil flow spread out all through the clutch pack. Those I just took and put dots on the 12 ribs with a magic marker to try and keep oil flow uniform.Those twelve holes were all .101 as well. 


 The next pic is a shot of the outside of the stock boss and shows the two innermost holes. So the two ribs in the center of this shot will get a hole in each one, placed out further on the boss to get better and more uniform coverage.  

'03 WR450 clutch 005.JPG

'03 WR450 clutch 006.JPG

Oh the bike you had pictures of on your thread, Is your clutch a drag?, It looked like these coolgraphics_zps826b2651.jpg


I used to have these Dirt Digit graphics:



It seems that the holes did help in your situation but I am wondering if you are not just masking some other

problem with your clutch.   I have 9 WRs including 3 2003 models and while the clutches do drag they are nowhere

near the extreme that you described with yours.     It really sounds like your clutch was having an issue beyond

the "normal" WR450 clutch drag...


The WR250 crowd does a lot of clutch tinkering but those clutches are notorious for annoying amounts of drag,

usually noticeably worse than the WR450.

 Maybe mine THOUGHT it was a 250!


I have three myself a 400 and two 450's but this one was so bad as mentioned I did not like riding it much do mostly to the hard starting issue associated with the clutch drag, so it was mostly a garage queen. THAT ended this Spring and I went through the clutch about 10-12 times since then. I measured and checked everything....repeatedly Nothing was wrong...but  now after riding it yesterday I am positive we are going to get along just fine!


 I have a friend who is a real outstanding motorcycle guru and even he was at a loss. Said I should just give up and go over to the dark side....KTM's. I have to admit I thought about it a couple times!

Edited by ThumpMe

Your inner basket seems to have groves/marks on it. That's 1/2 your problem, also leaves me to believe your outer basket has to have them on there as well. Maybe you missed my post on here, but those marks that are on that baskets are enough to not let the clutch disengage properly while pulling on your lever. Holes may have helped your clutch pull but as those groves get deeper you will be back right where you started.

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