clutch woes

While trail riding today the clutch on my WRR started slipping badly. I was able to ride it home but if I gave it gas from cruising speed it slips. The engagement also went from within an inch of the bar to nearly full extension. It happened suddenly, just after riding through some mud (that is, spinning the wheel under power).

I've checked the adjustment. I drained the oil--it looks black like oil with ~2k miles does but not out of the ordinary.

The bike has about 2600 miles on it. I bought it new last year and I've been the only rider/owner. I ride it on dirt and commute on it about 60/40.

I doubt it's my clutch habits--everything I've owned since I was 16 has had a clutch and none have worn out prematurely. This is not my first dirt bike.

So: what can cause a clutch to suddenly go from properly adjusted to engaging at the end of the lever travel and slipping badly? I'll take it apart and take a look this week but any insight would be helpful as I'm a shade tree mechanic when it comes to this sort of thing.

thanks,

-morgan

Did the oil stink?

What sort of oil did you put in the crankcase? (previously)
Oils with anti-friction additives can cook the clutch.

YZEtc wrote:

Did the oil stink?

No, it seems normal.

TwilightZone wrote:

What sort of oil did you put in the crankcase? (previously)
Oils with anti-friction additives can cook the clutch.

Castrol Actevo 10w-40. It's motorcycle oil of that's what you're asking.

-morgan

It seems I burned the clutch--see photo below. The friction plates read 0.011 to 0.012 so are on the border of the spec (0.114-0.122). I have never seen a WR clutch plate but I presume they're not supposed to be that black.

They certainly don't look healthy compared to these:
https://wr250rforum.forumotion.com/t7588-how-to-repair-replace-a-burned-clutch?highlight=clutch

The bike is heavily used as a dirt bike, does 2600 miles seems like a short life? Are OEM plates preferable or might I get better life out aftermarket plates?

And why did the clutch go all of a sudden? Shouldn't the friction point have worked out slowly until there was no adjustment left?

thanks,

-morgan

No, unless you fry your clutch very quickly to the point of practically grinding considerable plate material off of them in very short order, your clutch can start slipping without even noticing a change in clutch lever free play or position.

It is very possible for a clutch to slip even though the plate thickness is still specified as being OK when you measure them.
That's because even though they are still thick enough, their frictional properties have been changed because they've been overheated and cooked, and instead of the surfaces being grabby, they're glossy and slippery.

Possible reasons for a slipping clutch?

What gearing (number of teeth on front and rear sprockets) are you using?

Do you make a habit of "riding the clutch", as when slipping it a lot when wanting to avoid downshifting, taking off from a stop in 2nd gear, or using the clutch to hold you from rolling backwards while on a hill with the engine running and the transmission in gear?

How much clutch lever free play do you keep your clutch cable adjusted at?

You been practicing wheelies, jumps, or other stunts that require use of the clutch?

YZEtc wrote:

No, unless you fry your clutch very quickly to the point of practically grinding considerable plate material off of them in very short order, your clutch can start slipping without even noticing a change in clutch lever free play or position.

It is very possible for a clutch to slip even though the plate thickness is still specified as being OK when you measure them.
That's because even though they are still thick enough, their frictional properties have been changed because they've been overheated and cooked, and instead of the surfaces being grabby, they're glossy and slippery.

Possible reasons for a slipping clutch?

What gearing (number of teeth on front and rear sprockets) are you using?

Do you make a habit of "riding the clutch", as when slipping it a lot when wanting to avoid downshifting, taking off from a stop in 2nd gear, or using the clutch to hold you from rolling backwards while on a hill with the engine running and the transmission in gear?

How much clutch lever free play do you keep your clutch cable adjusted at?

You been practicing wheelies, jumps, or other stunts that require use of the clutch?

The gearing is stock.

I don't ride the clutch per se but much of our riding is tight Northeast woods so involves riding the clutch at low speed through tight trails. My commute is in city traffic so also involves a lot of clutch.

I do not wheelie, stunt, etc.

My other commuter bike is a Yamaha single (MZ Skorpion) and I've been commuting on it in city traffic for 10+ years and the clutch is fine. My previous dirt bike was a KTM 300exc that saw almost exclusively trails and its clutch was fine.

It must just be tight woods riding. I'm loving the bike so perhaps I subconsciously ride it harder than my previous bike(s).

Thanks for the advice.

-morgan

My advice:

Stock gearing is too tall for trail riding, especially in the woods.
I've found this out for myself when I owned a 2008 WR-250R and trail rode it a lot.

The bike comes with such a small-diameter rear sprocket (43 teeth - how many dirt bikes come with a rear sprocket with 43 teeth?) only as part of getting the bike past EPA-type drive-by noise tests.
Stock, the bike is geared for a top speed of around 90 mph.
Do you need that in the woods?

I went with 12/47 sprockets for my WR-250R, and I used the bike for trail riding and commuting back and forth to work on secondary roads.
Worked very well for me, as the bike felt much peppier without having such tall gearing to pull, felt geared correctly for the woods (no sky-high first and 2nd gear to work against you in the tight going), and still had an 80mph top speed.

If you fear a smaller front sprocket than the stock one, 13/51 sprockets is practically the same ratio as the 12/47 I used.

YZEtc wrote:

My advice:

Stock gearing is too tall for trail riding, especially in the woods.
I've found this out for myself when I owned a 2008 WR-250R and trail rode it a lot.

The bike comes with such a small-diameter rear sprocket (43 teeth - how many dirt bikes come with a rear sprocket with 43 teeth?) only as part of getting the bike past EPA-type drive-by noise tests.
Stock, the bike is geared for a top speed of around 90 mph.
Do you need that in the woods?

I went with 12/47 sprockets for my WR-250R, and I used the bike for trail riding and commuting back and forth to work on secondary roads.
Worked very well for me, as the bike felt much peppier without having such tall gearing to pull, felt geared correctly for the woods (no sky-high first and 2nd gear to work against you in the tight going), and still had an 80mph top speed.

If you fear a smaller front sprocket than the stock one, 13/51 sprockets is practically the same ratio as the 12/47 I used.

That's interesting and I think perhaps right on. I actually like the stock gearing for road riding which I do a fair amount but your point is well taken. I'm due for a chain in the not too distant future--I'll try 12/47.

Incidentally: why would I fear a smaller front sprocket?

Another option would be swapping between sprockets for dirt/street use. The front sprocket is a pretty quick swap if memory serves.

thanks,

-morgan

>"Incidentally: why would I fear a smaller front sprocket?"

If you are: (heavy, or let the chain go without lube, or maybe out of adjustment) you will eat up the 'chain guard'... the plastic that protects the swingarm.
Note it usually wears out from underneath, and can tear off the protection by the swingarm pivot, then it eats the aluminum on the frame.
Since I went to 14x50 sprockets, not showing a lot of wear.

I recommend 13x48 or 14x50 gearing. If you go 14x50 you can easily drop the front sprocket to 13 for big time torque.

12/47 is really a trail oriented gearing. I would suggest 13/47 for good all around riding. I am planning on 14/51 when I replace my sprockets to help with slider wear.

I would use a different type of oil from now on. I ride 13,42 on a 130/90 tire for the past 4 years and the clutch is mint.

Is that the only oil you ever used? I would 100% sure you didn't use the wrong oil previously. See owners manual. No sense fixing the clutch and ruining it again if that was the case.

gatorfan wrote:

Is that the only oil you ever used? I would 100% sure you didn't use the wrong oil previously. See owners manual. No sense fixing the clutch and ruining it again if that was the case.

It's the only oil I've used in the WR--I'm quite sure as I standardized on it a few years ago. I've been using it in my MZ 660 (Yamaha motor) for years and many miles with no ill effects. I recently started using it on my CBR600F4 so the jury is still out there.

I think I'm going to to start by lowering the gearing before chasing an oil issue as I do a lot of low speed trail riding on this bike and the clutch plates are visibly burnt and worn out.

thanks for the advice,

-morgan

morgan9283 wrote:

The bike is heavily used as a dirt bike, does 2600 miles seems like a short life? Are OEM plates preferable or might I get better life out aftermarket plates?

And why did the clutch go all of a sudden? Shouldn't the friction point have worked out slowly until there was no adjustment left?

]

I burnt my clutch up at about 3000 miles. When I did it it was technical trails, which I'm not very good at, and I had stock gearing. When it went I had almost no warning. It was like, "hey, this feels funny", to I have nothing in almost no time. I can't speak to other brands, I just went back oem, but I regeared lower (14/49) and its been much better. I now almost never ride the clutch.

For those of you that are using a 14 or 15, do you have room for a case save? The piece that keeps the chain from coming into the case if it breaks.

japako wrote:

For those of you that are using a 14 or 15, do you have room for a case save? The piece that keeps the chain from coming into the case if it breaks.

I'm running a 14/49 and the factory cover on the sprocket fits, Bigdog runs a 14/50 and he has a VW sandman sprocket cover http://bigdogadventures.com/WR250R.htm about 2/3 down the page he has a picture of it. It's tight with a 14, I doubt a 15 would fit. Why would you want to run a 15 up front?

Potentate wrote:

japako wrote:

For those of you that are using a 14 or 15, do you have room for a case save? The piece that keeps the chain from coming into the case if it breaks.

I'm running a 14/49 and the factory cover on the sprocket fits, Bigdog runs a 14/50 and he has a VW sandman sprocket cover http://bigdogadventures.com/WR250R.htm about 2/3 down the page he has a picture of it. It's tight with a 14, I doubt a 15 would fit. Why would you want to run a 15 up front?

I was really interested in the 14, but typed in the 15 also.. lol
That's good to know it will fit without a problem. I'm using a 13/48 and am not happy with 1st that much. 2nd and up is great. This is all rough dirt trails with hills.
I looked at the 52 tables, but it does not look like it changes that much. And a 14/52 is the same as the 13/48.

I'll have to give it more thought..