CR250R: gear shifter and front sprocket seals? Go ahead and replace?

[BlackCR25098]

I purchased my ignition side crank seal a while back, and installing it soon. While on the topic of seals and while I was looking at the "crank-case" microfiche on motosport's OEM section for my 98 cr250, I spotted these other 2 seals (1 behind gear shifter and another behind front sprocket). One behind the gear shifter, and also another back behind the sprocket.

Fairly certain I have not had any leaking issues from either of these seals, but I'm all about some "preventative maintenance"...Can either one actually leak gear oil or something else? Can they cause serious problems if and when they do go bad? I know they can't cause air leaks, but we've only rebuilt the top end of my 98 cr250 motor since I've got the bike back. It runs as good as any, but these seals I guarantee ain't been touched since 1998...

-Are they hard to replace? Or do they need anything special to pull em' out or tap new ones in?

-If it's about like the crank seal then I feel pretty confident I can do it and get them in straight.

-Should I put grease or any other type lube on any of these? If so, where?

So yea, while I'm doing the crank seal I figured why not do these 2 as well...Are there any other motor seals I'm missing that I can replace without splitting cases? The clutch side crank seal is on the list too btw

Just wanted to learn a little about them and see about replacing before I buy new front sprocket and just as preventative maintenance. Don't want no leaks or surprises.

Thanks for any help ?

Griffin

[HRC27]

My opinion on this is if it's not broke don't fix it. It's not that they're hard to replace, it's just not necessary unless they're leaking. A buddy of mine has my brother's '98 CR250 now and those seals are still fine. You can actually make matters worse by nicking the seal (esp the shifter shaft) and causing a leak.

When you put that crank seal in make sure to note how deep the current one is driven in and drive the new one in the same depth. You do want to put a little grease on the crank seal to aid installment but wipe it clean afterwards. If it has a spring on the back side of the seal, grease all the way around the inside of it to keep it in place.

Not crank seals but here:

Best of luck. ?

Edited May 21, 2012 by HrcRacing27

[xtonycrx]

I wouldn't bother replacing the seals yet. Worst case is they start to weep a bit of tranny oil and you notice it after a run. I have never seen them blow out and leak the oil all out at once.

[BlackCR25098]

My opinion on this is if it's not broke don't fix it. It's not that they're hard to replace, it's just not necessary unless they're leaking. A buddy of mine has my brother's '98 CR250 now and those seals are still fine. You can actually make matters worse by nicking the seal (esp the shifter shaft) and causing a leak.

When you put that crank seal in make sure to note how deep the current one is driven in and drive the new one in the same depth. You do want to put a little grease on the crank seal to aid installment but wipe it clean afterwards. If it has a spring on the back side of the seal, grease all the way around the inside of it to keep it in place.

Not crank seals but here:

Best of luck. ?

I wouldn't bother replacing the seals yet. Worst case is they start to weep a bit of tranny oil and you notice it after a run. I have never seen them blow out and leak the oil all out at once.

Okay, Thanks a ton for the picture HRC that helps tremendously, although those look like good ol' fork seals, but I get the idea for sure. On the crank seal, I definitely will note where it sits currently, good tip, but I've heard a couple of times the spec is "flush" with "beveled edge"? Or 2mm in, which flush with this beveled edge and 2mm in are the exact same spot apparently, but I just don't know what this beveled edge is. I guess I will know when I see it.

I'm having the local shop I trust remove my flywheel for literally a couple bucks, then I'm going to tow it right back home and get to removing the stator...Never done this before a little nervous on that part, but as far as replacing the seal sounds pretty simple:

Thread a wood screw (or a couple) into the seal and pull her out, noting it's position.

-Grease new seal inside lip, if it has the circular spring like my fork seals do, or just particularly on the INSIDE of the seal, not the outside rim.

-SLOWLY drive the new seal in even as possible with a deep well socket that fits best, and wipe any extra grease splooge clean.

-Re-install stator (lining up the notch line in the stator with notch in the case?) Guess I'll see that when I get to it also..

-Re-install flywheel..

Other small concerns:

-The shop said I WON'T need a flywheel puller or anything special to re-install the flywheel, that correct??

-One other guy said to use a air tool for that 17mm nut that goes on the shaft, but I am not a big fan of air tools at all...They cause problems being way over-torqued so was he full of it on that? Or can I just use a regular old socket wrench and torque it to manual's spec? I don't have an impact air thing anyway, and will check the manual for torque spec.

That sound about right?

Thanks for yalls time and help..GREATLY appreciated...Want to be sure I have it all straight and do this right, it's my first time.

Edited May 21, 2012 by BlackCR25098

[HRC27]

You won't need anything to put it back on but a socket. I usually put them back on with a butterfly impact so I can control the torque better. Mine can be turned down. Of course, a torque wrench is fine. Just need a way to hold the countershaft sprocket. Maybe put it in gear and have someone hold the rear brake if you don't have a holder.

[BlackCR25098]

You won't need anything to put it back on but a socket. I usually put them back on with a butterfly impact so I can control the torque better. Mine can be turned down. Of course, a torque wrench is fine. Just need a way to hold the countershaft sprocket. Maybe put it in gear and have someone hold the rear brake if you don't have a holder.

Now, is this the nut that goes on that rod you're talking about? The 17mm one? I'll need to hold the countershaft sprocket? Is that separate from putting in gear and braking? Sorry for more questions, but I haven't had to do this yet. I have heard of this technique, but just not sure exactly which step of the process it applies to.

Edited May 22, 2012 by BlackCR25098

[HRC27]

Now, is this the nut that goes on that rod you're talking about? The 17mm one? I'll need to hold the countershaft sprocket? Is that separate from putting in gear and braking? Sorry for more questions, but I haven't had to do this yet. I have heard of this technique, but just not sure exactly which step of the process it applies to.

Yeah, that's it. I would try putting it in gear and having someone hold down on the rear brake then torque it to 40lbs or whatever it is for a 250. I have a holder so I could hold the countershaft sprocket with the bike in gear but, as mentioned, use my impact turned down a bit.

[BlackCR25098]

Very cool. Where the heck did you get this holder?

[seanmx57]

use a long screwdriver thru the spokes in first gear to hold the tranny/motor for the FW or CS.

If you change the seal behind the CS change the collar too. Same with the crank seal. The collars get grooved and they should be changed as a set. I keep an extra collar/seal on hand at all times now for the CS. Had one let go the other day on a motor with less than 100 hours on it that gets washed plenty and not ridden in mud much at all. I would't change em till they leak or I was rebuilding a lower end.

Spraying a little brake cleaner on the crank seal while it's running will tell you if it's bad and clean things up at the same time. If the motor wants to die it's sucking brake cleaner in. Either works too and will rev the motor, it's not real great for it though.

some folks use 2 screws to pull old seals.........

[BlackCR25098]

use a long screwdriver thru the spokes in first gear to hold the tranny/motor for the FW or CS.

If you change the seal behind the CS change the collar too. Same with the crank seal. The collars get grooved and they should be changed as a set. I keep an extra collar/seal on hand at all times now for the CS. Had one let go the other day on a motor with less than 100 hours on it that gets washed plenty and not ridden in mud much at all. I would't change em till they leak or I was rebuilding a lower end.

Spraying a little brake cleaner on the crank seal while it's running will tell you if it's bad and clean things up at the same time. If the motor wants to die it's sucking brake cleaner in. Either works too and will rev the motor, it's not real great for it though.

some folks use 2 screws to pull old seals.........

I've heard that tip about doing the collar and seal at the same time, but not all seals have a collar to go with them right?? Last I saw, the clutch side crank seal had a collar, but I did not see one for the ignition side seal? Let me know if there is one, so I can order it since I already got the crank seal here, ready to go.

I already did try that trick with carb clean way back before my top end (bike was surging then also) and it didn't raise idle or want to kill the bike?!? Indicating it was good, which was why I took my mind off of it for a while.

I don't know if you saw my actual thread about my bike lean surging, but I basically had it boiled down to 2 possibilities for air leak:

-Choke tower on my old carb

-Ignition side crank seal

As you may know, I recently put the NEW pwk carb on, with 2 rides (at home in grass field) and it has not been doing the surging with clutch pulled in at all like before, AND I got it fully warmed up today and rode for about 20 minutes..The problem completely went away ever since new carb went on...Those choke tower air leaks were very common on that PJ carb I used to run. I believe I'm going to the track tomorrow to ride to REALLY make sure it's gone, so my crank seal might not be leaking at all. As I said, it never indicated it was leaking with carb cleaner test a while back...BTW that pwk is everything it is cracked up to be, awesome.

Even if it is fixed and not leaking, I'm going to change it. Chalk it up to "preventative maintenance" since it will leak eventually, but if ignition side seal does have a collar to order with it please do let me know so I can buy it. From what I understand, the worn out collar will just wear out the new seal anyway, if it's not replaced. Thank you for the heads up. Hope this wasn't too much to read lol but had to explain the good news. First time I rode the bike, it wasn't surging but it was a quick ride, so I couldn't be sure until today when I rode.

Thanks again sean and hrc, greatly appreciated.

Edited May 23, 2012 by BlackCR25098

[HRC27]

Very cool. Where the heck did you get this holder?

It's a Motion Pro clutch holder but it will also hold the front sprocket. Got it from Rocky Mtn I think.

[BlackCR25098]

It's a Motion Pro clutch holder but it will also hold the front sprocket. Got it from Rocky Mtn I think.

Very nice!! Motion pro makes a lot of great stuff and one-off tools for my bike, like the rear wheel retainer ring to do rear wheel bearings...that exists no-where but dealerships and through motion pro...I had to take the rear wheel to dealer and he took it out for me, just like I'm going to take this flywheel and have it pulled.

Although for the Counter sprocket, I believe I will use the long screw-driver for sure...That sounds like it'll work the best, as long as the torque isn't something crazy, which I'm sure it isn't.

You know what's funny? Is I believe my crank seal isn't leaking at all. The surging air leak stuff went away with the new PWK carb..I've ridden it fully warmed up yesterday, and it didn't start up. Looks like maybe it was that crappy Keihin Choke Knob leaking...I even remember doing the carb clean crank seal test when we did my top end, and it indicated it wasn't leaking...

Still gonna replace it though..Chalk it up to "preventative maintenance", but I still need to find out if the crank seal has that collar I need to purchase too, like the clutch side seal does...