CRANK SEAL REPLACEMENT

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NOSHER
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CRANK SEAL REPLACEMENT

Post by NOSHER » Sun Nov 05, 2017 8:29 pm

Hi guys
engine now running but spewing oil out of both cans-- only light blue haze from the left but obscuring smoke from the right hand even after 20 mins warm up The more it was revved the more of a smoke cloud from the r/h can and both cans still spraying oil.
General concensus is crank seals gone and r/h prob sucking in gearbox oil as well.SILLY QUESTION to which i probably know the reply----can you replace the seals without splitting the cases>
I read the manual through re disassembly of bottom end but photos and text seem to jump stages and aren`t really that explanetery.
A blog with a series of pics on this subject would be great ---any takers?
YOU GET MORE POKES WITH TWOSTROKES !!

KRI
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SP_BOTT
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Re: CRANK SEAL REPLACEMENT

Post by SP_BOTT » Sun Nov 05, 2017 10:33 pm

can't remember now, but i don't think you can get the gear off the end of the crank easily, so therefor can't replace the seal, or at least not a diy job, would await the experts though.

NOSHER
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Re: CRANK SEAL REPLACEMENT

Post by NOSHER » Mon Nov 06, 2017 12:30 am

ok fella thanks for the reply--i hope some clever geezer on here has found a way to do it and lets us know--you never know with a bit of luck it may not be the seals leaking--has anyone used a leak down test kit to confirm this problem??
YOU GET MORE POKES WITH TWOSTROKES !!

KRI
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jarno
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Re: CRANK SEAL REPLACEMENT

Post by jarno » Mon Nov 06, 2017 8:50 pm

If there is smoke coming from both sides there is a possibility that the inner seals are leak ( the inner shaft is worn)
In both times you must split the cases.
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NOSHER
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Re: CRANK SEAL REPLACEMENT

Post by NOSHER » Mon Nov 06, 2017 9:42 pm

hi jarno thanks for the reply--bit strange this one----i changed the right hand carb(still don`t know why)For a spare i had lying around to see if the engine would start after weeks of possible ignition problems and still no start but now plenty of spark----i gave it one kick and the engine burst into life.
the engine did NOT blow smoke or oil spray previously when it was running until i fitted this r/h carb!!!!!!!!!!!!!!!!!!!!!!!!!!!
tomorrow i will refit the original carb and we will see what we will see(probably through a blue haze!!)
YOU GET MORE POKES WITH TWOSTROKES !!

KRI
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bsa70
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Re: CRANK Shaft cog

Post by bsa70 » Tue Nov 07, 2017 4:31 pm

hi i got the cog off using a sturdy bearing puller from jago, on amazon about 30 quid ,first i punched a straight line from cog to end of shaft using an i letter from letter punches as a reassembling guide,then pulled it off using puller.

NOSHER
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Re: CRANK SEAL REPLACEMENT

Post by NOSHER » Tue Nov 07, 2017 5:21 pm

hi beezer-thanks for the reply--is the cog an interference fit? or is it on a keyway? AND--

did changing the outer seals sort the problem(i`m assuming it was smoking badly?) or not?
YOU GET MORE POKES WITH TWOSTROKES !!

KRI
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JanBros
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Re: CRANK SEAL REPLACEMENT

Post by JanBros » Tue Nov 07, 2017 10:52 pm

you need to split the cases to change the seal,as the seal has as sort of lip that fits inside a groove in the cases
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NOSHER
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Re: CRANK SEAL REPLACEMENT

Post by NOSHER » Wed Nov 08, 2017 1:09 am

Yes Jarno-- i thought that might be the case(no pun intended!!)i`ve just found a picture of a seal and i can see that it has a raised profile on the outer seal surface obviously there to lock the seals in place under compression.
Lets hope i don`t have to fork out for a crank rebuild and the smoky cans settle down with a little more running at temperature.
YOU GET MORE POKES WITH TWOSTROKES !!

KRI
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bsa70
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Re: CRANK SEAL REPLACEMENT

Post by bsa70 » Sat Jun 02, 2018 4:22 pm

NOSHER wrote:
Tue Nov 07, 2017 5:21 pm
hi beezer-thanks for the reply--is the cog an interference fit? or is it on a keyway? AND--

did changing the outer seals sort the problem(i`m assuming it was smoking badly?) or not?
hi the cog is an interferance fit, so will need to be pressed back on, i had to pull off bearings ,and split cranks with press,to replace middle two seals then got a garage to press it back together and balance,this sorted smoking.

NOSHER
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Re: CRANK SEAL REPLACEMENT

Post by NOSHER » Sat Jun 02, 2018 10:45 pm

Thanks for the reply Beezer and I`m still trying to figure out, if the crank seals are gone then why does it start first prod every time and go like s--t off a shovel? if the crank seals have hardened(not been on the road for 20 years remember)or are not sealing how is it getting crankcase compression which is after all how a two stroke engine gets its compression and performance.i`ve rebuilt engines before when they have bearings worn or barrels and pistons worn or broken or seized but am still loathe to send this engine into a circa £500 rebuild when it starts no problem goes like the wind has no loss of performance but the smoke screen and oil spray is still a worry and is still keeping the bike from being back on the road .
YOU GET MORE POKES WITH TWOSTROKES !!

KRI
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podman
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Re: CRANK SEAL REPLACEMENT

Post by podman » Sat Jun 02, 2018 11:54 pm

If the performance is good and it isnt consuming gearbox oil then it points to the seals being OK and perhaps an issue with the pump over oiling?

That said, I owned and rode my RD500 for 2 years with a similar concern, that had sat for some years and for a few miles( around 10-15) it performed well, then performance would drop off, it always started first kick and behaved itself in every other way.

After a while, I had it dyno’d which showed at first the BHP wasnt too bad, then the engine got hot and the seals started to fail...

Now its rebuilt with new seals of course it performs as it should, hot or cold..

Good luck and let us know the end result please.

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Re: CRANK SEAL REPLACEMENT

Post by NOSHER » Sun Jun 03, 2018 11:09 am

hi--thanks for the input Pod---I`ll leave it alone for a bit while I concentrate on my vfr400 carbs rebuild--more info to come.
YOU GET MORE POKES WITH TWOSTROKES !!

KRI
CBR250RR
CBR400RR NC23
vfr400 nc30

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