MRC Forum- brought to you by www.morini-riders-club.com

As part of my work to incorporate a spin on Oil filter on my 350, I need to use a 1/8 Oil pressure switch. Can anyone tell me at what pressure I should have the warning light coming on to detect diminished Oil pressure. Most systems seem to activate at such a low pressure that severe damage is already done by the time you get the red light.
Thanks.

I use a pressure gauge and I think it is the way to go.

If you want a light I would suggest it comes on at at least 25 psi,,,30 psi would be better based on my high speed runs....

Here is what I see on the gauge: 65 psi at cold start up,,,,60 psi when warm and going at speed,,,,, 55 psi when slowing down and coming to stop...

and I'm running 40w Castrol GT oil in up to 100 degree F desert heat.

I think 50w is too heavy based on what I see for my use..... maybe it is OK for lots of slow idling in traffic with a high mileage engine but not for high speed use.

Rule of thumb is if the pressure drops to half of normal shut it off ASAP.... 60 psi is normal at cruise speeds....

Robert in California

sheddweller wrote:As part of my work to incorporate a spin on Oil filter on my 350, I need to use a 1/8 Oil pressure switch. Can anyone tell me at what pressure I should have the warning light coming on to detect diminished Oil pressure. Most systems seem to activate at such a low pressure that severe damage is already done by the time you get the red light.
Thanks.

What you really need to know is the sort of pressure to be expected at idle rpm with a hot engine. In many cases this is a lot lower than you might expect, hence most of the switches available from your motor factors will be switching at a comparatively low figure. If they didn't you'd be in a panic every time you got the engine really hot then pulled up to a traffic light. At idle revs it doesn't need a lot of pressure to be safe as there is very little load on the pressure sensitive bits (the shell bearings) I think as the oil path is very short in a '70s Morini and there are few potential pressure leak joints, all supplied by an efficient oil pump we have little to worry about.
A mod worth thinking about might be to incorporate a woodruff key in the oil pump drive scroll rather than rely on that nut that needs a special socket being tight. I don't want to machine a slot there for the key though!
I like the idea of a pressure light and the filter canister in theory, but think that in practice you give your engine a few more potential leak points and a light to get neurotic about. What if the wire fell off? What if the switch bust? What if the switch fell out of its thread? Or the oil filter failed? Bulbs can be unreliable too? Or your main battery fuse is blown, cos the engine will still start and now the light won't work? OMG! LoL etc

This is a very wordy way of saying 'if it ain't broke don't fix it!'. I know it isn't what you wanted to hear so sorry for that!
All just my personal opinion of course and not backed up by NASA or MIRA or even the IMF

Motorboy,
I really do appreciate you supplying an answer to the question I asked. While my straying from original spec causes palpataions for most people on this forum, I'm trying to avoid another gauge in the cockpit.
Steve,many thanks for your thoughts but I do fear that by being so negative about my plans you are discouraging many owners from modifying their own machines and helping me with my enquiry. That is precisely the reason I withdrew from this forum a few years ago.
However, having just rewired my 350 I really enjoyed your tongue in cheek comments about adding extra wiring complications.
Regards
Garry Roberts.

Race cars often have a high pressure switch that works as you're suggesting - it's on at idle and doesn't turn off until you get the engine over a few thousand RPM. There are two advantages to a switch like this - first, it's self testing every time you let the motorcycle idle, and second, you are aware of a failure earlier. 20 PSI is pretty common; there are also adjustable ones, and others that go up to 60 PSI.

I'd go with 20. I think the real value will be in getting used to where it normally shifts on/off when you're riding and seeing how that changes over time.

Sam

sheddweller wrote:Motorboy,
Steve,many thanks for your thoughts but I do fear that by being so negative about my plans you are discouraging many owners from modifying their own machines and helping me with my enquiry. That is precisely the reason I withdrew from this forum a few years ago.
However, having just rewired my 350 I really enjoyed your tongue in cheek comments about adding extra wiring complications.
Regards
Garry Roberts.

Hi Garry, I'm really sorry if you thought I was being negative or pouring scorn on your plan? That wasn't my intention and I apologise if it came across like that. I hope too that I wasn't the cause of you leaving the forum in the past? I don't remember it anyway.
All I was trying to say was that all these mods have been done already so you're not breaking new ground or any rules in my book, and that in my opinion it isn't worth the work. That's all, sometimes what we read on these forums comes across differently to what the poster had in mind. It is a risk we have to face when communicating worldwide with people from other cultures and languages etc.

I'm certainly no rivet counting originality fetishist but I do think the people who made these bikes had good reasons to do what they did. And after learning the hard way with countless 'modifications' and 'upgrades' on my own bikes, that only a few of them are worth the effort.

Back to your original query, I'd actually prefer a fairly low pressure switch, as an engine with a decent mileage on it may well set the light flickering and worrying you unnecessarily.

So, hows the cricket going?

Later 350 and 500 models were equipped with a pressure switch.

I'm sure if you phone NLM and have a word with Rob, he'd give you the part number of the pressure switch they supply and you could look up the pressure rating if you can't use it direct.

Sam,
Thanks for the race car analogy. I think the notion of seeing how it changes over time is the key to peace of mind.
Steve,
I was reluctant to counter your good suggestions with your negativity, but I have seen that "if it ain't broke don't fix it" mentality cut short many discussions on this Forum. If you'd like an example, do a search for 'Left side gear change'. Perhaps I am a little sensitive but my regular response to comments about what was so good about the 70's is to ask if the speaker still seeks out 40 year old tyres.
Lambertini did a great job with what he knew at the time. How many features of that design were still visible in the recent bikes?
If you'd like to know how comments like those are perceived, I'd suggest you approach someone who isn't involved with the Forum.
Show them my query.
Ask them to compare your response to that of Motorboy.
Point out that your tag has a bright Red MRC beside it, and ask them to judge how deviations from the original design are welcomed on this Forum.
I'm not suggesting you publish the findings, and as you point out, there are language and cultural elements at work. You do a great job in keeping this Forum relevant, but I fear that the whole pool of knowledge, experience and enthusiasm is sometimes smothered by the 'seen it all before' attitude of the regular contibutors.
I returned to the Forum seeking information and got a wealth of it. Until Paul suggested to ring Rob at NLM I hadn't even considerd doing that. My 350 had a failed Pressure switch, which I replaced with one of similar specs but the info supplied by someone who is running a gauge is what I really needed to make an informed choice. Facts allow others to make their own choices. I'll ask for opinions when I want them.
Sorry I don't follow the cricket. Hope those pesky colonials aren't using their population numbers as another excuse for unseeming behaviour.
Garry Roberts

No I don't follow the cricket either. That was a weak attempt at humour and obviously a waste of time. My apologies again. I've no idea what you mean about bright red MRC tags either? Maybe it indicates being a club member, but I can't see it on my screen. It can't mean that my opinion is worth more than that of anyone else. Also the club has a disclaimer, they aren't responsible for comments by anyone else etc. I certainly know (for a fact) that I don't keep the website or forum going, and won't trouble your sensitivity with my opinions (formed from real life experiences in the motor/motorcycle trades rather than pub ideas) from now on. I won't be leaving the forum in a huff either.
Cynical I might be, but I can deal with that thanks. It does help me though, dealing with the fact that internet forums are mainly full of opinions instead of fact. I actually find them both enjoyable, maybe I do need therapy after all? I know sarcasm is the lowest form of wit but, I'm comfortable there too.

Bye bye!