Author Topic: Rocker oil feed  (Read 2295 times)

Online TimK

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Rocker oil feed
« on: 01.09. 2016 01:54 »
While I was masking up my 59 Gold Flash oil tank I noticed that one of the holes that the banjo feeding the rocker box sits over was blocked by a steel pin (see pic).

Has anyone else noticed something similar on their bikes?

I can't think of any good reason to restrict the flow of oil to the head unless if it may have been a ploy by a previous owner to stop the engine smoking - When I bought the bike I only ran it for about 2 minuted before deciding to do a total rebuild, and it didn't seem to be smoking excessively them.

Has anyone got any ideas?

Tim
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Tim Kerridge
Australia

Online mugwump

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Re: Rocker oil feed
« Reply #1 on: 01.09. 2016 11:45 »
Its probably just a drip feed ( by a wick ) to the rear ( drive chain ) as long as you still have the 'T' off from the main oil return hose to the rockers thats ok. Its common to block off the drip feed to the chain and lubricate the chain manually, I use a spray grease.
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Re: Rocker oil feed
« Reply #2 on: 01.09. 2016 12:02 »
Quote
Its common to block off the drip feed to the chain and lubricate the chain manually,

this drip feed to the chain from the engine return is new to me, are you thinking perhaps of the tanks breather muwump, I know this is sometimes used to vapour the chain , I like you use a spray.

Don't think there should be any restriction at that point Tim, too much oil to the rockers is a perceived problem, check the holes in the studs that feed the rocker spindles, A's use a very small hole, other BSAs (Goldies I think, could be wrong help me lads) use studs with a bigger hole, this leads to over oiling of the rockers
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1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online Greybeard

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Re: Rocker oil feed
« Reply #3 on: 01.09. 2016 12:34 »
this drip feed to the chain from the engine return is new to me, are you thinking perhaps of the tanks breather muwump, I know this is sometimes used to vapour the chain
I don't know if all A's are like mine but the tank breather is plumbed so it exits over the gearbox sprocket; the chain gets oiled, (especially after I've over filled the tank!).
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Online KiwiGF

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Re: Rocker oil feed
« Reply #4 on: 01.09. 2016 12:46 »
Hi Tim, I don't think that added restriction will have much effect at all, the copper oil pipe to the rockers has a small I.D. and in my opinion provides a far bigger restriction to flow, being far longer in length.

Having said that, there are different banjo components available (at the oil tank end) which have larger oil hole diameters than standard which may also be a factor here. It would be worth checking you have correct one, maybe the blocked hole is to compensate for a incorrect component *dunno*

From memory there is a restriction in the oil return at the tank end which causes a small increase in pressure in the banjo, which causes a small amount of the returning oil to divert up to the rocker, too little restriction in the oil return, and too little oil will go to the rockers. On my bike I would describe the flow to the rockers as a slow "dribble".

This thread has some relevant info......
http://www.a7a10.net/forum/index.php?topic=592.msg3489#msg3489

And so does this...
http://www.a7a10.net/forum/index.php?topic=3800.msg26437#msg26437




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Offline chaterlea25

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Re: Rocker oil feed
« Reply #5 on: 01.09. 2016 14:12 »
HI Tim,
If possible remove the offending piece from the hole
The amount of oil to the rockers is regulated by the size of the holes in the banjo bolts at the rockerbox
From memory A7/10 size is 3/64 ??
I have found B series drain bolts fitted that have something like a 3/16th hole  *eek*

HTH
John
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Online TimK

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Re: Rocker oil feed
« Reply #6 on: 02.09. 2016 07:06 »
Thanks for the collected wisdom Gents. I'll remove the obstruction as it doesn't seem to be a tight fit in the hole anyway, and a lose lump of metal in the engine oil system doesn't seem like a good idea to me.

I checked out the oil feed holes to the rockers and they're both 1/8th", which doesn't fit in with either 3/64ths or 3/16ths. I'll leave them be for the moment, but they may be my first thing to change if the engine is a bit smokey when I get it running again.

cheers

Tim
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Tim Kerridge
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Re: Rocker oil feed
« Reply #7 on: 02.09. 2016 09:41 »

Quote
Don't think there should be any restriction at that point Tim, too much oil to the rockers is a perceived problem, check the holes in the studs that feed the rocker spindles, A's use a very small hole, other BSAs (Goldies I think, could be wrong help me lads) use studs with a bigger hole, this leads to over oiling of the rockers

Quote
I checked out the oil feed holes to the rockers and they're both 1/8th

so looks like maybe a previous owners attempt to cure too much oil to the rockers was to restrict it at the bottom as opposed to the top where BSA decided it should be.
Just for clarity I did reply earlier but probably forgot to press post or keyboard missed the press *, any way the restriction I refereed to was to the rockers and GB the plumbing from the tank breather is not a standard fitting but I think one that is popular, I like mugwump use a spray.

* off subject but a little warning I have found with cordless keyboards  that moving them further from the dongle can mean them missing key press's, in my case putting the KB on my lap mutes it
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1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline chaterlea25

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Re: Rocker oil feed
« Reply #8 on: 02.09. 2016 22:02 »
HI Tim,
I/8th is waaaay too big  *ex*
The feed pipe is 1/8th bore ????

John
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Online TimK

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Re: Rocker oil feed
« Reply #9 on: 03.09. 2016 00:44 »

John - I didn't check the feed pipe bore, 1/8th is the size of the hole in the banjo bolts on the rocker box. On closer inspection the holes looks a bit rough and I suspect the large holes may have been a PO modification.

Do you think I should replace the bolts with some that have the correct size feed hole?

Other than possibly feeding too much oil to the rockers and some of it finding it's way past the valves could the excess oil cause other problems?

Cheers Tim
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Tim Kerridge
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Offline chaterlea25

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Re: Rocker oil feed
« Reply #10 on: 03.09. 2016 01:06 »
Hi Tim,
Quote
Do you think I should replace the bolts with some that have the correct size feed hole

Yes
They were designed to meter the correct amount of oil to the valve gear

John
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Re: Rocker oil feed
« Reply #11 on: 03.09. 2016 09:58 »
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could the excess oil cause other problems?

if there is more coming in than can quickly drain away then it will find it's way down valve stem and cause smoke,  it's also giving the pump more work but pump should handle it.
Definitely agree with John, get the proper bolts.
the rockers don't require a lot of oil but the camshaft  also gets a bit from down the pushrod tunnel as well as other feeds and mist
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1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online Joolstacho

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Re: Rocker oil feed
« Reply #12 on: 04.09. 2016 00:32 »
I'm sure I remember reading that the inlet side (rearward) oil feed hole was smaller than the exhaust (front) one, because otherwise the 'first' outlet would get too much oil and the second would not get enough because of less pressure. In other words, to encourage equal amount of oil into both spindles.
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Online TimK

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Re: Rocker oil feed
« Reply #13 on: 04.09. 2016 07:31 »
Quote
I'm sure I remember reading that the inlet side (rearward) oil feed hole was smaller than the exhaust (front) one, because otherwise the 'first' outlet would get too much oil and the second would not get enough because of less pressure. In other words, to encourage equal amount of oil into both spindles.

I've just checked the parts list and both bolts are the same number so they should be the same size hole. I also had a look on the Draganfly site and the bolt pictured there has a hole that looks closer to 1/16th than the 1/8th that mine are - so mine would have been passing about 4 times as much oil!

Cheers

Tim
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Tim Kerridge
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Re: Rocker oil feed
« Reply #14 on: 04.09. 2016 09:22 »
Quote
the 'first' outlet would get too much oil and the second would not get enough because of less pressure.

Don't see that being an issue Jools as they both come off a T junction
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All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco