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drca

Kickstart and gear shaft seals replacement...

10 posts in this topic

One of the rear engine mount on my 2013 Gas Gas TXT broke, so the frame is off to the welder to get fixed (bash plate flattened from too much bashing, which spreads out the frame, which in turn puts pressure no the engine mounts and I'd rather have the engine mount break than the engine cases crack!)  Now... I could bash on things less, but then I'd have to become a better rider first!

2018-02-12 21.45.22.jpg

 

So it's a good opportunity to finally do winter maintenance on the bike (which I keep pushing off because of the just incredible weather we've been having here in California).  I have a long list of things to do and it includes changing the seals around the kick starter shaft and gear shaft, both of which are seeping oil.

2018-02-13 08.41.55.jpg

2018-02-13 08.42.09.jpg

Can I do that without taking the engine apart?

Thanks.

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Yes you can. To get to the kickstart seal, tip the bike over to the left side and remove the clutch case, leaving the water pump hoses intact. Pry out the seal and replace.

Hard to tell from the photo, but it looks like the oil is weeping out from the gearbox output shaft. Invariably, it is not the seal that is passing, but rather one or both of the 2 O rings that are placed behind the output shaft sleeve. The output shaft has a push fit sleeve over it, that the oil seal runs on. The sleeve can be twisted and pulled off with pliers. Usually, one O ring comes away with the sleeve, inside a recess, the other O ring (25 x 1mm from memory) is likely on the shaft. This is usually the source for leaks, but definitely change the oil seal anyway, they don't cost much. Bye, Peter B.

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41 minutes ago, peterb said:

Yes you can. To get to the kickstart seal, tip the bike over to the left side and remove the clutch case, leaving the water pump hoses intact. Pry out the seal and replace.

Hard to tell from the photo, but it looks like the oil is weeping out from the gearbox output shaft. Invariably, it is not the seal that is passing, but rather one or both of the 2 O rings that are placed behind the output shaft sleeve. The output shaft has a push fit sleeve over it, that the oil seal runs on. The sleeve can be twisted and pulled off with pliers. Usually, one O ring comes away with the sleeve, inside a recess, the other O ring (25 x 1mm from memory) is likely on the shaft. This is usually the source for leaks, but definitely change the oil seal anyway, they don't cost much. Bye, Peter B.

Thanks!

The kickstart side seems pretty straightforward.

One the sprocket side, that looks a little more complicated... If I get it right, on the sprocket shaft there is (starting from the inside of the engine):

  • A 25 x 2.0 o-ring - ME25632025 (#25 on the 1st exploded view below)
  • a 25 x 1.5 o-ring - MT280212025 (#29 on the 1st exploded view below) 
  • A bushing - MT280236046 (#24 on the 1st exploded view below).
  • An oil lip seal - ME25636024 (#37 on second exploded view)

And to get to all of this, it means removing the left side engine case, which requires removing the ignition cover and the ignition...  Anything else?

So now that I have the engine out of the frame, that might be a good time to do this service I guess!

Screenshot - 2_13_2018 , 5_08_25 PM.png

Screenshot - 2_13_2018 , 5_06_57 PM.png

Screenshot - 2_13_2018 , 4_51_11 PM.png

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 The kick start seal can be replaced by just taking the kick start off. The seal will come off quite easily with a small pick. In fact most of the time the seal has pushed out and just needs re-seated. I would not worry about your other so called leak. Clean it all up and see what is really leaking. It could just be the carb dribbling or the crankcase vent is just spitting a little.

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If I may, I have a question for drca related to the situation; how do you ensure that your fixed frame will align with the engine? Do you simply make the weld with the engine in place? Or do you just "eyeball it", and then open up the mounting holes later if required (say with a file)?

Thanks.

Dale

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2 minutes ago, d2w said:

If I may, I have a question for drca related to the situation; how do you ensure that your fixed frame will align with the engine? Do you simply make the weld with the engine in place? Or do you just "eyeball it", and then open up the mounting holes later if required (say with a file)?

Thanks.

Dale

Well, it's a trials steel frame without a lower cradle so it really isn't the stiffest thing around especially at the front (you can bend the thing by hand if you are not careful!).  So my welder just makes sure that the crack in the mount is closed (tap it into place with a hammer) and weld it back together.

Then the mounting sequence is: drop the engine in the frame, put the swingarm spindle in, put the lower rear engine bolt in, then the front engine mount bolt then the top bracket and slowly tightened everything in the same order a little bit at a time.  The challenge will be the bash plate.  If it's new (i.e. unmolested) it should drop pretty easy. If it's been bashed (flatened) , then mounting it can range from being a challenge to impossible.

In the end my frame could be twisted a bit, but since trials is about riding on crappy terrain with under inflated tires...  it doesn't make much difference to me :-)

Hope this helps.

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You need a mallet to return the sump to its original shape and it's worth fitting new rubbers between the guard and the engine cases or you may quickly end up back where you started. 

Sump guard is quite easy, fit the front blots,  just a few turns. Then get the rubbers in place and if necessary use longer bolts to get the rear bolts started and then swap the correct ones in one at a time. 

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I have a bike that has oil leaking from the countershaft seal. Parked in the garage, I would find a small puddle of oil on the floor. Now I use a triangle stand and park the bike leaning in the other direction. Problem solved!

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17 minutes ago, baldilocks said:

You need a mallet to return the sump to its original shape and it's worth fitting new rubbers between the guard and the engine cases or you may quickly end up back where you started. 

Sump guard is quite easy, fit the front blots,  just a few turns. Then get the rubbers in place and if necessary use longer bolts to get the rear bolts started and then swap the correct ones in one at a time. 

Yeah... Got myself a new bash plate!  Then I'll beat the old one into submission as a spare ;-)

I have all new rubbers too.

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Hi drca, you can access the 2 O rings from the outside. Just need to remove the gearbox sprocket circlip, sprocket then use pliers to twist and turn the sleeve directly behind the sprocket and remove the sleeve. Makes sense to make sure the weepage is not just from carb overflow first as lineaway mentioned. Bye, Peter B.

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