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Leaking oil by Front Sprocket.

10K views 15 replies 5 participants last post by  BlockIsland 
#1 ·
My poor 525 is leaking a bit of oil from behind the front sprocket. Its not alot, but I HATE oil leaks because so much dust sticks to them and makes a mess.
I'm assuming I hurt the seal when i broke the front sprocket bolt off, and had to heat the bolt to break the loc-tite.

What is involved in fixing this leak?
Hopefully its a seal that can be replaced from the outside........
 
#2 ·
if you did not roach the bearing it can be fixed from the outside. in fact the leak is pretty common and happens alot when guys run non ktm front sprockets. the aftermarket sprockets are sometimes a bit thinner than the factory ones are. the two big items that go bad or wear out is the cupped washer #22 and the little rubber o-ring #25 that is behind the sleeve #18.

the leak happens because there is not enough force being applied by the thinner sprocket + the cupped washer looses it tension and both can cause a leak to happen. like i said, its very common on the dirt bikes.





i would just order everything and replace them all because of the heat you applied. if you need a different sprocket than what came on it from the factory, just make sure to use a ktm sprocket or one that you know is made to the same specs for thickness.

you are gonna want to order .... 18, 20, 22, 25, 32. if you are careful you can get a small screw into the lip of the seal and pry it out. be careful to not nick the aluminum race that the seal sits on as it can leak if you mess it up. take you time and work from the inside out and you will get it to pop out with no damage done to the motor.




year 2009
model 525 xc atv
part transmission ii - countershaft

item part # description retail
1 83133010000 countershaft 08 $82.61
2 83033012000 idler gear 2.g. 33t 07 $58.73
3 83033042000 needle bear. 22x26x10 slotted $4.78
4 83033041000 needle bear. 22x26x13 slotted $5.63
5 0417025000 circlip sw25 $3.26
6 83033014000 sliding gear 4. g. 28t 07 $54.21
7 83033032000 distance disk 25x30x0,2 $2.18
7 83033033000 distance disk 25x30x0,3 $2.18
8 83033022000 stop disk 22,6x30x1,5 18t $2.95
9 83033013000 idler gear 3.g. 30t 07 $49.69
10 83033015100 solid gear 5.g. 26t 07 $54.21
12 83033018100 idler gear reverse-gear 07 $54.21
13 83033017000 sliding sleeve reverse-gear 07 $42.91
14 83033025000 stop disk 20,2x31,x1,5 $3.87
15 83033044000 needle bear. 22x26x12 $9.08
16 83033011000 idler gear 1.g. 35t 07 $63.25
17 49032012000 stop disk 17,2x30x1,5 $4.02
18 54633014100 spacer bushing 12mm $31.71
20 50033029013 front sprocket 13-t $26.24
20 50033029014 front sprocket 14-t $26.24
20 50033029015 front sprocket 15-t $26.24
22 59033034044 screw 10.9+spring washer $4.89
25 0770020220 o-ring 25,12x1,78 nbr70 $2.06
30 0625062036 ball bearing 6203 rsh c3 $12.50
31 49030023000 cyl.roll bearing nj205 $76.15
32 0760324571 shaft seal ring 32x45x7 bslnbr $2.96
 
#3 ·
The machine shop that removed the broken bolt did NOT put that cupped washer back on, because they used a bolt they had in stock n a different combo of washers. I'll try just getting the right bolt m washer first. I am running a renthal sprocket but I ran it on my 07 with no issues.
 
#5 ·
Yea, ya have to run the cuped washer. It puts pressure on that o-ring to keep it from leaking.
 
#6 ·
Bob, would you suggest that I get the JUNK ktm sprocket bolt too? That bolt is scary soft, and wants to break always. My machine shop used a harder bolt, so it doesn't want to break off. I'll go look and see, as I know they used a lock washer just for good measures to keep the bolt from backing out. I might even still have that sprocket bolt washer, and if so, its going back on!
 
#7 ·
Ok, I just looked, I have a new KTM bolt, and 2 washers.
I'll install the bolt and washer with BLUE locktite and the new cupped washer tomorrow, and see how it goes.
Glad I had the stuff laying around.
 
#8 ·
I don't know if I would use a second added on washer in this application Brent.

The cupped washer ( The factory calls it a spring washer ) works with the gear thickness to give the proper amount of side pressure on the o-ring to seal the oil in. If you add the second washer you could be putting too much pressure on the KTM washer which would transfer to the o-ring and might compress it too much.

I see no problem with running a better quality sprocket bolt though. As long as its the correct length and has the same profile on the back side of the bolt as the stock one does. Thats gonna be the tricky part.

If you look the stock bolt has a machined raised surface that matches the cupped washer, they kinda lock together to only allow so much pressure on the sprocket from the spring ( cupped ) washer.

If you look at it, it will be clear how it works.



If it were me, I would buy a new factory bolt and washer and other stuff I pointed out in my first post. Clean out and run a tap thru the output shaft to get rid of all the old loctite and then just use the stock stuff with a good dose of loctite and let it sit for a day to fully cure and then be on your way. Thats what I do and its worked fine for 3 years now.


Like I said before, guys over on KTM talk have had this same thing happen to them many times when they use different aftermarket parts and stuff. Most every time when some one re-does it like the factory, using factory parts, their oil leak goes away.
 
#9 ·
Not planning to run 2 washers. Just have 2 in my inventory!
 
#10 ·
So, flat side OUT on sprocket is the correct way right?
The sprocket was on backwards, and the cupped washer was not there, so i'm sure this will likely cure my leak.
 
#11 ·
You want the cupped washer installed so that the cupped part is facing the sprocket. This is what puts the tension of the sprocket and o-ring.

I hope it fixes the leak.
 
#12 ·
Ya, but sprocket goes 2 ways, I'm sure its right now.........
Machine shop put it all on wrong when they installed a different bolt for me.
 
#13 ·
I believe that the sprocket can go on in either direction. As long as it is touching the cupped washer correctly and the spacer correctly it should not matter.
 
#14 ·
is matters with the chain allignment. If I run it the other way, then the sprocket ends up closer to the motor, and the cupped washer really doesn't sit well on that shoulder on the sprocket. Its on according to the shop manual. Glad I found my 2nd shop manual, the first one that I Pirated from my dealership was completely BLANK in the engine section. It had all the bullets, and pictures, but all the words were missing! No wonder I never could figure out any of the engine related stuff.
 
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