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Post by scooter on Apr 2, 2020 14:42:02 GMT 1
hi all ive just freshly rebuilt my 250lc and pressure tested it to discover its leaking from the alternator crank seal (new) my main question is can i split the engine whilst still keeping the pistons and barrels on i was thinking of putting some bolts in the top cases were the side cases bolt on and zip tying the crank to the bolts with a bit of slack to remove the offending seal the pressure test is losing 3psi over 6 mins  |
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Post by midlifecrisisrd on Apr 2, 2020 15:29:00 GMT 1
Yes you can do it upside down
Just put a couple of bolts in the lower case side cover bolt holes and cable tie the gear shafts to them so they lift off with the lower case and don't come away from the selector forks
Biggest question it was it a genuine Yamaha seal
If not strip and change
If it's genuine I'd run that and then check after a few hundred miles to let it "seat"
It looks like it's leaking through the centre at the crank
Steve
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Post by scooter on Apr 2, 2020 15:35:41 GMT 1
hi steve yes its leaking from around the crank i got the seal from norbo which are genuine but not in the bag do some leak from new and need seating
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Post by jackjabba on Apr 2, 2020 16:10:34 GMT 1
What pressure are you starting with?
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Post by Yogi on Apr 2, 2020 16:18:18 GMT 1
As Steve said I wouldn’t worry about that for now
Might seal if you turn the engine over a couple of times
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Post by scooter on Apr 2, 2020 16:24:50 GMT 1
hi jackjabba im starting at 6 psi cheers yogi its all new rebore pistons etc so might run for a few hundred miles and retest
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Post by midlifecrisisrd on Apr 2, 2020 16:25:37 GMT 1
Never had one leak myself
Was the crank ridged where the seal runs
Don't know why if genuine it wouldn't be in the bag 🤔
Steve
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Post by scooter on Apr 2, 2020 16:47:55 GMT 1
hi steve the crank was nice and clean in the seal area, thats whats stated on norbos website gen yamaha just not in bags
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Post by rich on Apr 2, 2020 17:11:23 GMT 1
hi steve the crank was nice and clean in the seal area, thats whats stated on norbos website gen yamaha just not in bags Which must beg the question 'Where are the bags??' Genuine seals, and any other genuine parts for that matter will be in individual Yamaha packaging full stop. If they aren't, then I would question their authenticity. |
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Post by muttsnuts on Apr 2, 2020 18:32:16 GMT 1
genuine seals say ARS on them, its on the inner/recessed part of the seal, if it doesn't say ARS then its not genuine.
I buy boat loads of crank seals from Fowlers, doesn't matter if I order one or 50, each one comes in its own bag. never had one bag with say 10 seals in it been sent
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Post by scooter on Apr 2, 2020 18:37:40 GMT 1
hi dave even if it is genuine do you think i should replace it or leave as others have said see if it beds in
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Post by tony2stroke on Apr 2, 2020 18:39:24 GMT 1
Sorry about this question, but is the seal in the correct way around, looks like I can see the spring around the seal, if that's the case I am sure it should be the other way round, flat surface facing out dish side with spring facing in.
That would explain why its leaking.
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Post by scooter on Apr 2, 2020 18:48:05 GMT 1
ive put it spring out the same as the other side of the crank
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Post by tony2stroke on Apr 2, 2020 18:50:19 GMT 1
ive put it spring out the same as the other side of the crank That's the problem, they are the wrong way round mate, they won't seal that way round. That goes for both sides of engine, you need to turn them around. |
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Post by rich on Apr 2, 2020 18:53:04 GMT 1
Primary gear side seal can only be fitted one way ie with the castellations towards the bearing. The flywheel side seal isn't handed and has springs on both sides so can be fitted either way.
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Post by scooter on Apr 2, 2020 18:54:10 GMT 1
the other side has to be spring out so the castillations press against the bearing
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Post by tony2stroke on Apr 2, 2020 18:59:03 GMT 1
First time I have ever heard about seals with springs either side, if that's the case then sorry.
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Post by tony2stroke on Apr 2, 2020 19:05:34 GMT 1
1 more question, is it writing facing out, I can't see it would work the same either way round, but I may well be wrong, I would install it writing facing out.
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Post by scooter on Apr 2, 2020 19:33:33 GMT 1
not sure myself tony i always ask on here everyday is a school day
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Post by LC_BOTT on Apr 2, 2020 20:41:44 GMT 1
Just wondered if you put any oil or grease on the shaft before fitting the seal?
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Post by 4l04ever on Apr 2, 2020 21:53:51 GMT 1
If there was no oil on the shaft, it may not seal. You could try tipping the engine on it's right side and filling the left crank seal with two stroke oil, then turn the engine over, to try to get some oil into the seal contact area. Then dry off and retest.
I had a crank seal that leaked when fitted dry, but I retested after running in for a bit and was okay.
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Post by jackjabba on Apr 3, 2020 13:04:30 GMT 1
I just had some crank shaft seals from Norbo and they were not in bags either. They are fitted now so not going to pull the engine down to check them.
Just checked in my spare parts box and I have what I thought were some pattern seals and the Large one when opened did have ARS on it. They were not in Yamaha bags.
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Post by scooter on Apr 3, 2020 14:00:17 GMT 1
This is a close up of my seal not got ars on it got fwj  |
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Post by jackjabba on Apr 3, 2020 15:27:18 GMT 1
What about the Primary side one?
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Post by 0h5h1t on Apr 3, 2020 15:36:46 GMT 1
Did some investigation for you and checked the Genuine "bagged" seal that I recently replaced during the Winter rebuild on my motor. It too has FWJ 25 40 stamped on it and like yours also has Ars stamped further round to the left. That said. It should have been in a Genuine Yamaha bag as all Yamaha crank seals are. Now, if you sourced a shed load of Ars seals from the manufacterer and could get them at a hugely reduced cost over the same seal in a Yamaha bag...... would it be ethical to sell them as Genuine or not... not for me that one but I suspect that's what has happened here. I myself have had some very dubious parts sold as Genuine that were clearly not and they were returned along with a "concerned" phone call to the supplier. All that said it looks like your seal is of the right type, made by the right people. Only you can decide if it's woth pulling out and refitting again, but if it was me (Particulary during this lockdown) I think I would source Genuine Bagged seals and oil the shaft on rebuild just to be sure. A few quid and a few hours for peace of mind that your motor is not going to run lean.  |
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Post by scooter on Apr 3, 2020 15:37:21 GMT 1
I've not had the drive cogs off that side yet as it's not leaking but will probably replace them both so will take a picture then going to wait for seals to arrive before splitting the cases
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Post by midlifecrisisrd on Apr 3, 2020 15:46:08 GMT 1
Before you strip it it do a couple of things
First very carefully see if you can peel the inside of the seal open a little and get some oil inside
Then with a hairdryer heat the seal then turn over the engine a little
Then retest and see if it's any different
Steve
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Post by scooter on Apr 3, 2020 15:53:45 GMT 1
Cheers Steve will try that
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Post by andymoore on Apr 3, 2020 16:41:32 GMT 1
It will not seal properly till it's in the right way round mate pain in the ass but worth doing good luck with it🙈👍👍
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Post by stusco on Apr 3, 2020 16:47:51 GMT 1
If the yellow ring is showing I think it’s the right way round
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