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Feb 13th, 2017
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5TA leak behind primary? #767938
03/12/19 9:30 pm
03/12/19 9:30 pm
Joined: Aug 2017
Posts: 26
Essex, UK
H
hemroid Offline OP
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Essex, UK
Just finished building the bike below.

All is well apart from a pretty heavy leak from behind the inner primary just below the front sprocket, it looks like its coming from the screw hole on the pic from underneath.

I took the primary cover off and there was alot of oil!, to much surely? I suspect the level was so high its been seeping out of the nearest place possible like behind the sprocket?

Does the oil in the tray look to much? what is supposed to limit this oil?

[Linked Image]

[Linked Image]

[Linked Image]

[Linked Image]

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Re: 5TA leak behind primary? [Re: hemroid] #767959
03/13/19 12:32 am
03/13/19 12:32 am
Joined: Jan 2014
Posts: 4,409
Australia
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NickL Offline
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Australia
Looks like a lot of oil, probably the crankshaft seal wants replacing.
Primary chain looks a bit 'tired' too. See what it's like after adjusting.

If those 2 small holes go back into the sump, someone may have converted it to
breath into the primary, in which case those holes are a bit high up.


Life is much too important to be taken seriously.
Re: 5TA leak behind primary? [Re: NickL] #767989
03/13/19 7:34 am
03/13/19 7:34 am
Joined: Aug 2017
Posts: 26
Essex, UK
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hemroid Offline OP
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Essex, UK
Thanks Nick. Did these not breath into the primary then? Perhaps ill tighten the chain and run it and see where it comes from.

Re: 5TA leak behind primary? [Re: hemroid] #767990
03/13/19 8:38 am
03/13/19 8:38 am
Joined: Aug 2017
Posts: 26
Essex, UK
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hemroid Offline OP
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just had a thought, ive had a standard inspection cap and not a breather cap above the primary, would this cause the oil to fly all over the place and create the leak behind the sprocket you thin?

Re: 5TA leak behind primary? [Re: hemroid] #768051
03/13/19 11:51 pm
03/13/19 11:51 pm
Joined: Feb 2014
Posts: 538
Cork Ireland
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chaterlea25 Offline
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Cork Ireland
Hi
The hole you indicated is one of the screw holes that retain the plate behind the clutch,
There's a seal in the centre of the plate behind the clutch
It could be loose screws? or a leaky seal
Originally those small holes into the crankcase would not have been there, so it has been modified
Check and see if there is a seal on the crank behind the alternator?
No seal there means you need to complete the breather modification by adding an outlet to the primary case

John

Re: 5TA leak behind primary? [Re: hemroid] #768077
03/14/19 7:00 am
03/14/19 7:00 am
Joined: Aug 2017
Posts: 26
Essex, UK
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hemroid Offline OP
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Essex, UK
Thanks John, if i decide to go back to stock and fill the holes can i add a new crank seal from the outside if i remove the sprocket?
Thanks Steve

Re: 5TA leak behind primary? [Re: hemroid] #768087
03/14/19 10:50 am
03/14/19 10:50 am
Joined: Jan 2014
Posts: 4,409
Australia
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NickL Offline
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Australia
The seal presses in from the primary side.
The later 500's all vented via the primary.
The levelling holes on your one have been drilled a bit high, you only
need the bottom of the chain covered. It may be worth while drilling a hole
a bit lower, it only needs to be 3mm.Put plenty of grease on the drill and
you won't get swarf into the sump.
A barbed hose fitting into the top of the primary cover will work as a breather exit
just run the hose up over the rear mudguard.


Life is much too important to be taken seriously.
Re: 5TA leak behind primary? [Re: hemroid] #768123
03/14/19 5:44 pm
03/14/19 5:44 pm
Joined: Feb 2006
Posts: 732
Qld, Aust and Otago,NZ
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Ginge Offline
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Is it engine oil or gearbox oil? If gearbox oil it could by leaking past the gear box seal and running down the splines in the main shaft. You can remove the main shaft, refit the seal and coat the splines on the shaft with a sealant before refitting the sprocket onto the shaft.

If it is engine oil then it must be coming from inside the sump through those holes. They are much bigger than the holes used in the later 500's that breathe into the primary. I think they are much lower as well.

You could seal them with epoxy and revert to seperate primary oil. Some use ATF. Engine oil can cause sticking clutch plates if it has too many additives in it.


Ginge
Re: 5TA leak behind primary? [Re: hemroid] #768136
03/14/19 10:54 pm
03/14/19 10:54 pm
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Posts: 4,409
Australia
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NickL Offline
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Australia
Hmmmmm. Oh well, i'll leave you to it.


Life is much too important to be taken seriously.
Re: 5TA leak behind primary? [Re: Ginge] #768137
03/14/19 10:55 pm
03/14/19 10:55 pm
Joined: Sep 2013
Posts: 1,916
Pacific northwest
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quinten Offline
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Pacific northwest


It looks like
To much oil in the primary because the breather mod
was not finished ,... or perhaps , not done correctly

You should-not have that level of oil with either... the original sealed primary
Or
The modified to 1970s " open primary " style .

Open primary uses no main seal and small drain back holes ... to control oil level over chain .
And then a baffled-hose out the top of the primary.
The factory also eliminated the hollow cam timed breather .

Your bike may or may not be running its original cammed breather ... or a breather thats plugged as part of the incomplete mod.
If you go back to a sealed primary , make sure the timed breather is there , and not plugged.
If running and open primary ... this is often plugged.

Original old style breather tube is shown here ( this tube is also know to oil much more than the chain )
... so is another source of leaks in this area .

[Linked Image]

Below is a pic of a later T100 factory open primary set up .
Note the small drain back holes locations , looks similar to yours
And the black sheet metal baffle ... for the breather hose .
[Linked Image]
If you add a breather to the oil filler plug , one of your simpler options ...it may not work as cleanly as the factory baffle ,
You may have to experiment with how large a hose and how vertical it runs ... to control oil mist .

.

Re: 5TA leak behind primary? [Re: hemroid] #768205
03/15/19 9:04 pm
03/15/19 9:04 pm
Joined: Feb 2014
Posts: 538
Cork Ireland
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chaterlea25 Offline
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Hi Steve,
As your engine is an early distributor model there maybe another source of oil leakage
I could of course be 100% wrong here though, as its been a long time since I I worked on a 500 twin
On early bikes the high speed gear bush finished flush with the end of the gear, oil migrated along the bush and leaked out
later (I do not know when) the bush was lengthened to protrude through the sprocket plate seal
The bronze wears of course over time though
It should be possible to check if the timed breather is still fitted ? ( a theory??)
Place the end a piece of tight fitting plastic tubing over the end of the breather pipe
As you rotate the engine it should be possible to blow through the tube into the engine when the valve lines up with the inner engine passage
and not be possible to blow through at other positions ???

The other contributors have addressed your other questions I think

John (hoping I'm not typing complete rubbish)

Re: 5TA leak behind primary? [Re: hemroid] #768227
03/15/19 11:43 pm
03/15/19 11:43 pm
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Australia
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NickL Offline
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Australia
Just a few points, sorry but i can't resist......

There is way too much oil in the primary, this is caused by the modified breathing setup being done incorrectly.

The original factory mod in 1970 drilled 1mm holes level with the lower chain run, this worked as a shaded
vacuum system to draw the oil mist back into the sump as the engine ran. The mod as carried out on your bike
has 2 holes about 1/8 or so drilled in around the same place as the factory did, this will not work like the factory
setup as they are much larger.
What will happen is the oil will fill to that level, this is not the required oil level, it should be much lower, the lowest
part of the chain is the only part that needs to be covered. To correct this as i said, a small 1/8 hole drilled level
with the lowest run of the chain will do, if not then blank them off and fit a crank seal and go back to standard,
BUT you will have to check you have a timed breather fitted.

I converted my 69 daytona to breath this way and it worked very well, i just ran a 10mm hose up from the
primary cover and over the rear guard like the 70 onwards did. It's a mod i have done to all my bikes for years.
One of the advantages of unit motors in my book, there is a huge plenum there, so use it.


Life is much too important to be taken seriously.
Re: 5TA leak behind primary? [Re: hemroid] #768251
03/16/19 10:36 am
03/16/19 10:36 am
Joined: Aug 2017
Posts: 26
Essex, UK
H
hemroid Offline OP
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Essex, UK
Thanks everyone, a real great help.

The cam breather isnt blocked off so i will do that. I will also fit a breather on the primary oil filler hole, then give it a go and see if the leak goes away. If the leak is still present ill drill some lower holes, if that doesnt work ill bring it back to standard.

ill let you know what happens.. waiting on a new gasket..

Re: 5TA leak behind primary? [Re: hemroid] #768258
03/16/19 1:41 pm
03/16/19 1:41 pm
Joined: Aug 2015
Posts: 1,337
Bolton Lancs UK
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Andy Higham Offline
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Bolton Lancs UK
It isn't an oil leak, It is tears as the bike is crying about what you have done to it


BSA B31 500 "Stargazer"
Greeves 200 "Blue Meanie"
Greeves 350
Greeves 360
Suzuki GSX1100 EFE "Sorcerers Apprentice"
GM500 sprint/LSR bike "Deofol"
Jawa 500 "Llareggub"
Aprilia RSV Mille "Lo Stregone"
'35 & '36 OK Supreme
Kawasaki ZZR1400 "Kuro no senshi"
Re: 5TA leak behind primary? [Re: hemroid] #768276
03/16/19 5:15 pm
03/16/19 5:15 pm
Joined: Aug 2017
Posts: 26
Essex, UK
H
hemroid Offline OP
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Joined: Aug 2017
Posts: 26
Essex, UK
Haha, Im sure it was more happy as rusty frame at a swap meet and a load of bits scattered all over the country..


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