Honda-SOHC
SOHC.co.uk Forums => SOHC Singles & Twins => Topic started by: AndyD on July 07, 2024, 11:16:58 AM
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Hi,
Trying to get the CJ250t ready and on the road but another snag now with an oil leak.
Thought originally it was the gearchange lever seal - replaced this but leak returned straight away.
Running with engine side exposed shows the leak is from the final drive seal.
I think I know the answer but just wondered (hoped) if there is any way to replace this without splitting the crankcases etc.
From the parts drawings the seal appears to have a locating nipple but can't recall if it also has any lip set into the cases.
Advice very welcome
Cheers,
Andy
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I feel your pain Andy, same happened to me on the original build of the CB250RSA, the lip seal tore around the shaft and caused the leak.
I read up about pulling the old seal out using wood screws drilled into the seal itself and cutting the nib off the new seal but in the end I thought I'd rather do the job properly rather than risk another potentially catastrophic seal failure. I had to separate the cases but it wasn't too bad as the head and barrel etc could remain in situ. It took me an afternoon in the end (excluding getting the engine out and back in again).
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Thanks Dave,
Guess I'm pretty well resigned to having to strip her down again although I may put it off a while to rebuild some enthusiasm.
Was hoping to finally get some riding in this last few weeks and even bought a new helmet and gloves thinking the 250 would be ideal for start - best laid plans and all that!
Like you I'd seen a few stories of replaced seals without dismantling but doesn't really sound right somehow and always best to do it right.
I can't recall if it's possible to split the cases without stripping the top end at least saving a few gaskets and jobs! Will have to have a look at that and see what makes sense.
In the meantime must get busy with clearing some space in the garage and sheds - too many bikes / projects / spares and waning enthusiasm so think it's really about time for decisions on what to keep and what to get rid of.
Cheers,
Andy
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You can split bottom case off and leave everything top end intact
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Many thanks Bryan,
That should save a lot of grief (and cost) hopefully.
Just have to summon up the enthusiasm to drop the engine out and get on with it.
Cheers,
Andy
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If you need a hand Andy let me know, happy to provide some lifting power to get the engine out (and back in).👍
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Thanks Dave,
I may well take you up on the offer if that's OK - always fiddly getting the lump in and out without damaging all the shiny stuff!
I'll get the bits needed and try and formulate some kind of plan.
Cheers,
Andy
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No problem Andy, I'll be glad to help and with both of us on it we can hopefully get it out and back in within a day. A lot of effort to undo a few bolts to replace a seal worth £10 but worth doing properly just for piece of mind👍
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Thanks Dave,
I'm just thinking if I'll need to order any other bits beyond the oil seal for this.
If only going in from the underside (i.e top end untouched) I'm hoping the other oil seals etc. affected when splitting the crankcases can just be retained.
I'll have a study of the parts drawings and photos to see what could be affected.
Cheers,
Andy
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Hi Andy.
You'll likey need some Hondabond to rejoin the cases and some cellulose to clean the old hondabond off. Trouble is Hondabond goes off in the tube once opened, the tube I bought a couple of years ago was rock solid when it came to refitting my 400 cases, luckily I was able to to cut the tube open and rescue some from deep within the tube using a thin brush. You may need new gaskets for the side casings but if the bike hasn't been run they should be OK.
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The other seals can be replaced easily later if necessary, maybe a clutch cover gasket if it rips, i usualy like to fit new but as its nearly that you may well get away with it
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Not sure if its the original seal that has just started leaking or if its after a rebuild.
My only experience based on oil leaks from ADO15 Mini drive shaft output seals that started to leak is there is often a cause for seal failure. On the MIni it was due to wear in the differential that caused the seals to fail due to excess movement on the output shaft bearings.
If its just old age or damage when fitting a replacement should work - just make sure its not caused by excessive demands due to excessive shaft movement or corrosion on the shaft externals. Sorry if i'm stating the obvious.
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Finally getting enough renewed enthusiasm to replace the seal and running through the manual it says you can simply remove the bottom case without touching the clutch / oil pump and filter etc.
Sounds great and hopefully correct but looking at photos of the original build I'm wondering if this is possible as the gearchange bits straddle the case joint and sit behind the clutch.
Hope someone can confirm - manual option obviously saves time and effort but don't want to try it and find bits getting caught up when cases come apart.
Cheers,
Andy
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Its been that long i cant remember, which book are you reading, if Haynes not necessarily correct, you will have to take clutch cover off of course plus generator and sprocket cover
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Thanks Bryan,
It was in the Honda workshop manual and just sounded too good to be true!
[attach=1]
[attach=2]
Didn't want to risk anything so I took off the clutch and oil filter so everything was clear on the case joint - definitely needed as the gear change mechanism spans the case joint and would have been tricky to get cases apart and likely impossible to refit later.
With a bit of playing around with bench lift / small engine jacks etc. managed to get the engine out quite easily and without damage so that was a relief - don't think getting it back in will be so easy so may well see if Dave is still happy to help at that stage!
Cases came apart easily so just sorting a list of parts needed and will get these on order next day or two and then get ready for the next instalment.
Cheers,
Andy
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Well done for removing the engine on your own Andy.
Happy to help with the heavy lifting when required. I'm going on holiday from 29th Aug until 22nd September but available all other times👍
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All done!!
Thanks again for help and advice on getting this done.
Enjoy your holiday Dave, managed to lift the engine back in and it wasn't too bad in the end - it's more awkward than heavy to get wiggled into the frame.
Not bad with the 250, not sure I'd try with anything bigger any more!
All back together and polished back up.
[attach=1]
Interesting on the seal as I bought an original Honda one (as used in the first build) but also a pattern one from eBay out of interest.
The pattern one is nothing like the original and has no locating lug and worse has no holes for the oil passage in the casing - photos shows the differences.
[attach=2][attach=3]
Pattern seal would be easier to replace without splitting the cases but clearly wouldn't be right - I wonder how critical that oil passage is and how many engines now have this blanked off.
Cheers,
Andy
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Another technology fail with posting - this time only one picture appeared!
Hope these appear this time - finished (again) bike and pattern seal with missing oil passageway
[attach=1][attach=2]
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The bike looks fabulous! It brings back fond memories of my mate Steve who had a yellow one: the 'Flying Banana'. I rode on the back of it often down to the Railway Hotel in Bishops Stortford when I lived down that way - I had hair then :-)
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Thats a 350/400 four seal and i know they need the peg
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That looks amazing Andy, well done for the single handed lifting in and out!
Is this the original 250 you restored or is this the second one you had in bits a couple of years ago?
I'm sure if you were to sell it Mr Silver may be interested as I don't think he has one of these in his collection.
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You're right Bryan, it's the same seal on both bikes.
I'm not sure if the 400 also used the oil passage through the seal like the CJ but guess it would if it's the same part.
It always amazes me how poor some of these pattern parts are either in accuracy of manufacture or simply not being anything like the correct part.
Of course most sellers don't know or care so just copy the details over from the manufacturer no matter how inaccurate (or badly written).
Dave - thanks, yes this is the first one rebuilt a while ago, now going through the first round of fixing problems and leaks etc. after a bit of running.
Oil leak was a pain being a lot of work for a small part and afterwards nothing really to show for it but can't be avoided.
A couple of final bits to sort / tidy and she should be finished at last (until the next leak / noise / problem pops up of course).
Also replaced the steering head bearings as I wasn't happy with the roller ones I originally used - gone back to original ballbearings for top and now assembly feels much better.
Got the CJ360T rebuilt as well a while ago but only to a more 'lived-in' standard, ready to fill with oil and petrol and see if she runs well.
I'd put it on the backburner while trying to 'quickly' get the XT250 on the road as initially hoped this would be a simple tidy-up.
Of course that changed on closer inspection and has been fully stripped and rebuilt and still needs a few bits sorting but nearly there.
She'd had a really hard life and the PO had repaired / bodged just about every part of the bike and engine so has been a pretty extensive mechanical rebuild.
To be fair I can't complain too much as I happily remember some very interesting 'field repairs' as we called them back in the day which would horrify anyone digging up one of our old bikes now!
Cheers,
Andy