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Stupid question (again..) about the oil pressure relief valve..
Posted: Tue Jun 01, 2021 9:52 am
by jawa-enfield
Okay, i am almost finished with running in my overhauled 500 bullet.
I've come to onderstand that there is an oil pressure relief valve IN the crankshaft?
I did not notice it when (dis-)assembly.
some bloke told me he had big-end deprived from oil because the spring was too weak...
But.. where is it located??
Re: Stupid question (again..) about the oil pressure relief valve..
Posted: Tue Jun 01, 2021 10:25 am
by Adrian
It depends what year your crankshaft is. As far as I know, if your crankshaft has one it will be in the timing side mainshaft, but for SOME model years I understand that the factory didn't fit them! This is generally considered to have been a bad thing, although it's less of an issue if you fit a roller big-end bearing.
A.
Re: Stupid question (again..) about the oil pressure relief valve..
Posted: Tue Jun 01, 2021 2:21 pm
by jawa-enfield
It is a '94 inland model..
Re: Stupid question (again..) about the oil pressure relief valve..
Posted: Tue Jun 01, 2021 3:44 pm
by Adrian
By inland I guess you mean Indian home-market.
This from our hosts' technical notes:
FLOATING BUSH BIGEND: If the bigend is new or recently fitted the clearance between the
crankpin, floating bush and fixed bush may be too small. This results in excess pressure and
harder work for the oil pump worm and spindle, most of the Redditch Bullets have a pressure
relief valve in the flywheel end of timing shaft to help combat this. The Indian Bullets, with few
exceptions, rely purely on the oil pumps lifting off their seat as a crude pressure relief valve, but
we would rather see a constant high flow without high pressure, therefore the tolerances of the big
end are very important. This is not easy to check, but can be roughly checked by using engine oil
in a general purpose oil can with its nozzle inserted into the big end oil feed seal, you would expect
to be able to force oil through the big end.
If there IS a pressure releif valve, look for a slotted threaded plug in the flywheel end of your timing side mainshaft.
If there ISN'T one, our hosts sell lighter gauge springs for under the oil pump covers.
A.
Re: Stupid question (again..) about the oil pressure relief valve..
Posted: Wed Jun 02, 2021 6:58 am
by jawa-enfield
This means i should split the crankcase to check?
Hmm Untill now it works.. let's see for how long...
\Yes i mean home market.. it was imported by a private person, had single leading FB and a LOT of quality problems, especially the gearbox..
Re: Stupid question (again..) about the oil pressure relief valve..
Posted: Wed Jun 02, 2021 11:36 am
by Adrian
No need to split the crankcases, but next time you have the cylinder head and cylinder off for any reason you could probably use a dentist's mirror to check, with the big-end in the 3 o'clock or 9 o'clock position. If it's working OK, just let it run.
However, the parts book for the 1994 500 Bullet does not list a crankshaft pressure release valve, so it's most likely your motorcycle is one of the Bullets which doesn't have one. If they didn't bother fitting one to the export models, you can be assured that the home market models wouldn't have them either.
https://www.hitchcocksmotorcycles.com/p ... pages/1617
If you look at the on-line parts books for the UK built Bullets from the late 1950s you will see the ball, spring and screw plug which form the valve assembly are shown separately.
https://www.hitchcocksmotorcycles.com/p ... pages/1093
A.
Re: Stupid question (again..) about the oil pressure relief valve..
Posted: Wed Jun 02, 2021 5:33 pm
by Bullet Whisperer
Easiest way to check for a relief valve in the timing side mainshaft is to push a suitable length of rod [make sure it is long enough!] into the open end of the mainshaft. All you have to do is remove the quill bolt, push in the rod [or a pipe from a WD40 can will do] and when it comes to a stop, push a bit harder and feel if it has come to a dead stop, or if there is a tiny bit of extra, sprung movement. This will soon tell you which you have.
Re: Stupid question (again..) about the oil pressure relief valve..
Posted: Wed Jun 02, 2021 6:43 pm
by stinkwheel
Adrian wrote: ↑Tue Jun 01, 2021 3:44 pm
If there ISN'T one, our hosts sell lighter gauge springs for under the oil pump covers.
A.
Someone suggested to me that another way to do this is to fit 2 or more gaskets under the oil pump cover to make it easier to blow off the pump faces in the case of an over-pressure.