B25 Starfire oil pressure light comes on

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Darrell
Posts: 60
Joined: Mon Jul 19, 2010 6:50 pm

B25 Starfire oil pressure light comes on

Unread post by Darrell » Fri Nov 28, 2014 5:10 pm

Hi all,
Having just modified the breathing system on the Starfire with a pipe attached to the Rocker Shaft cover, I now get my oil pressure warning lamp flickering on at tickover once the oil has warmed up. Apparently this is not a new problem. Could someone explain to me please the science behind this ? I originaly modified the breathing system because the engine leaked lots of oil (yes, they all do that sir). I now have an engine that does not leak oil but that blessed oil pressure lamp gives me the creeps.
Cheers
Darrell

DerryUK
Posts: 107
Joined: Fri Dec 03, 2010 11:24 pm

Re: B25 Starfire oil pressure light comes on

Unread post by DerryUK » Fri Nov 28, 2014 8:23 pm

On the face of it the air pressure is now slightly lower on the spring side of the oil pressure switch. The oil pressure will be just the same though.

I'd live with it as low oil pressure isn't a problem just a sign of wear usually. The important thing in an oil system is flow. High oil pressure is just a waste of energy which is why F1 engines use circa 30 psi.

If you think about it just kicking your bike over you can generate 120 psi on a pressure gauge which is much higher than your oil pressure.

Derry.

Triton Thrasher
Posts: 774
Joined: Wed Feb 18, 2009 12:51 pm

Re: B25 Starfire oil pressure light comes on

Unread post by Triton Thrasher » Fri Nov 28, 2014 8:28 pm

Temporarily plumb an oil pressure gauge in and find out what the hot oil pressure is.

supersix
Posts: 1816
Joined: Wed Feb 18, 2009 9:23 am
Location: wigan and sometimes Scunny or Louth, Lincs

Re: B25 Starfire oil pressure light comes on

Unread post by supersix » Fri Nov 28, 2014 9:17 pm

If it's the original switch it could be worth replacing it. My 72 Lightning had a similar problem til I replaced the switch.

Darrell
Posts: 60
Joined: Mon Jul 19, 2010 6:50 pm

Re: B25 Starfire oil pressure light comes on

Unread post by Darrell » Fri Nov 28, 2014 10:18 pm

Hi Guys - thanks for your replies. Your words make perfect sense to me DerryUK and it is nice that you confirm the oil pressure will be just the same on the 'pressure' side. My Big End has only done 6K miles so I suspect there is plenty of life in them yet. When you said that oil flow is the important thing, I think I should have and will do - check what the return flow is like at the oil tank. When checking the Valve clearances the other day I did notice that as the engine was turned over by hand, there was a dribble of oil after every revolution - so I guess the oil pump does show some sign that it is working ? If the oil return flow is normal then I will think very hard about living with it as you suggest.

I was looking at a handlebar mounted oil pressure guage on the Morgo website this afternoon Triton Thrasher. It seems an ideal addition in such circumstances but at £50 bar a penny (scuse pun), it is maby a little too much having just paid out £560 on an N.E.B. clutch - but I know you are absolutley correct.

I am nerdish enough to actually have a log book for the Starfire and everything I do to it is written down - yes I know, too much time etc etc but, 7 years ago I had exactly the same problem Super Six, in that the oil pressure warning light came on at tickover. My solution then was to fit a new pressure switch as you suggest. 7 years ago it worked and my problem was solved so it might be an idea to fit another new one.

I will check the oil return flow first and then put another switch in (I have one in stock) and if the light still illuminates at tickover, I shall ask Santa to visit the Morgo website.

Fantastic response to my dillema guys. I am very grateful. Thanks.

Darrell

Triton Thrasher
Posts: 774
Joined: Wed Feb 18, 2009 12:51 pm

Re: B25 Starfire oil pressure light comes on

Unread post by Triton Thrasher » Fri Nov 28, 2014 10:33 pm

An oil pressure Bowden gauge permanently in place is a hot 60 psi oil spraying event waiting to happen. Ones with an electric sender are safer, but they fall to bits.

A used Bowden gauge from an old car or off any compressed air plant will work well enough, for long enough, to test the pressure, but it'll take a little work to set it up.

My Big End has only done 6K miles so I suspect there is plenty of life in them yet.
On a Starfire? Ok!

Darrell
Posts: 60
Joined: Mon Jul 19, 2010 6:50 pm

Re: B25 Starfire oil pressure light comes on

Unread post by Darrell » Fri Nov 28, 2014 11:06 pm

........ and there I was hoping I was going to get another shiny guage to stare at !! 60 psi of hot oil in ones mush cannot be ignored so ok, if I actually feel the need to check out the oil pressure after checking those others things - I suppose I should fit one up temporarily as you sugest Thrasher.

On a Starfire? Ok![/quote]

What is there about B25's that you know and I don't ? My last big end did a tad over 18000 miles - ok ok, it did get clean oil every 1000 miles. Starfires are good bikes if one is prepared to put in 2 hours maintenance to every 30 minutes of riding !! Mine has 41,091 miles on the clock - is this a record ?

Willpower
Posts: 679
Joined: Sat Feb 21, 2009 2:56 pm
Location: St. Annes on Sea

Re: B25 Starfire oil pressure light comes on

Unread post by Willpower » Sat Nov 29, 2014 12:40 pm

I'd be tempted to disconnect and live without the oil pressure warning light. Many other bikes don't have any visual indication and the button indicator was less than useful on my Bonnie, so I blanked it off. Keep the oil changes regular and you should get the recommended milage from your machine, before the need for overhaul.

Triton Thrasher
Posts: 774
Joined: Wed Feb 18, 2009 12:51 pm

Re: B25 Starfire oil pressure light comes on

Unread post by Triton Thrasher » Sat Nov 29, 2014 3:56 pm

I don't know much about them really and was slightly kidding.

I knew people with various versions of Unit singles, back in the good old days and they seemed a bit prone to mechanical disaster.

Darrell
Posts: 60
Joined: Mon Jul 19, 2010 6:50 pm

Re: B25 Starfire oil pressure light comes on

Unread post by Darrell » Sun Nov 30, 2014 7:08 pm

Hello Willpower - yep, I think as you suggest that I just live with this set up (including the modified breathing) and accept the low pressure oil lamp flickering at tickover. If it illuminates when I'm cruising then I know that WILL give me a scare but to disconnect it ? - I dunno. I take your point that there are a lot of bikes out there that have no indication as to what their oil pressure is doing - but I like 'knowing'. I recently fitted an ammeter to my Bantam and a few weeks later noticed the charging circuit was showing a large discharge during a ride. Had I not had the Ammeter to tell me this, I would have been carried on none the wiser until the battery would have let me down. When I got home I found that it was nothing more than bad connections on some bullet connectors - which was easy to sort out.

The Unit singles were thrashed alot 'Thrasher' by the young un's of the day. The inevitable problems associated with this is probably why the bikes were given such bad press. Yet these days the engines are widely sort after in competition circles and much has been done to make them 'bomb proof'. In the 26 years I have owned the Starfire, I cannot recall ever a time when 'nothing' needed to be done to it :roll:

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