Topic: 1974 CB550: Why is my oil light on at times?

[allhonda]

My new to me 1974 CB550,carbs now rebuilt, got my cam cover back on, adjusted valves, fired right up and I was going to go for a test ride and it starts snowing here in the Nashville TN area! Wont be riding this evening!?
Any way I have read somewhere that the oil light can come on sometimes when the bike is near idle. Is this true or would I have another problem. I ran the bike for about 15 minutes to get it hot, then I notice the oil light is on up to about 4000rpm on the tach but not when I revved it higher? What's up with this?  On start up I dont really see it until the engine starts to warm up and then I let it idle. Oil level is ok. 10w40 and new filter. Bike has 16,000 original miles. Just replaced the 6 sealing rubbers below the cam cover to stop the oil leak. Before this repair when I would ride the bike once it got hot I would notice this light would come on at or near idle. Is it set off by temperature or what? Thanks in advance.

[mlinder]

Means your oil pump is probably failing.

It is set off by pressure, or more precisely, lack thereof.

[Shoeboxjoe]

Oil is thinner when hot which is why the pressure light doesn't come on until the engine is warmed up. Just curious what type of oil did you use recently?

[bender01]

The oil pressure switch could could be going bad! Thats how mine acted! I got one from Honda and problem solved! Heres a pic. If you take off a tappet cover look for oil in the valve train while its running to be safe!

[Bob Wessner]

I too think the pump, or pressure unit may be the problem. Given your location and the current temps, the oil getting too hot/thin is not likely the cause.

[TwoTired]

Wouldn't it be nice if it was just the oil sending unit going weird when it was hot?  It's possible.  Any signs of leaking?  May leak faster and bleed pressure moreso when hot.

Take off the tappet inspection caps (right side and left side) and verify things are getting oily wet up there.  If so, it's probably false reporting by the sender.  If it looks dry up there, then the oil pressure is likely low.

Or, maybe when it was put it back together, the oil restrictors for the top end were left out, which will allow the pressure to bleed off faster when the oil is thinner and freer flowing.

If the top is oiled, step one is to do a substitution of the oil sender, old for known good, or install a pressure gauge to know for sure what the oil pressure is.  The sender should only go on below 7 psi-ish.  Below this pressure, the cylinder walls starve for oil.

Cheers,

[allhonda]

The oil I put in it last was purchased at Auto Zone, Castrol motorcycle oil 10w40. The motor on this bike was covered with oil when I bought it. I just installed new sealing rubbers which I think took care of the leak. Haven't had time enough to road test to make sure. Thanks for the input.

[camelman]

I had the same issue with a CB500, and it turned out to be the oil pressure sensor unit.  You can change it easily, and there are plenty of people on this forum who have extras laying around.

If you do not want to drain your new oil when you swap the sensor, then have someone lean the bike over while you perform the task.  It swaps out pretty quickly, so your helper won't have to stand there too long.

Camelman

[dave500]

only a bit of oil will leak out when you remove the sender,the bypass valve is not sticking?

[RippinSVT]

Mine will flicker here and there. I choose to ignore it for my own peace of mind.

[Spanner 1]

Ya can have one of my spare ones ( oil pressure sender ) if you can get your bike over to me in 37217 , Priest Lake area, fellow Nashville member  
Wait  ... that's if a 750 o/p switch is the same as a 550 one, anyone ??

[Kong]

$35 with shipping:
http://cgi.ebay.com/ebaymotors/Honda-Oil-Switch-350-400-500-550-650-750-900-1000-1100-/220721284051?pt=Motorcycles_Parts_Accessories&hash=item33640383d3

[Oddjob]

There is another possible answer. Many moons ago now I rebuilt a CB500/4 engine and everything was perfect. However on a long ride out one day whilst going at high speed down a motorway the engine oil light suddenly started to flicker, pulled over and everything sounds ok, no nasty grinding noises meaning an imminent seizure so I took it easy on the way back and limped home. As the engine had done over 100K I supected the oil pump had finally given up the ghost, but no, upon ispection it was fine, a few scours on the tips of the rotors but everything including tolerances were fine. I however decided to replace it just in case, still got the light flickering. New sender was fitted with the new pump so it couldn't be that. I drained the oil and changed the filter, here's where it gets interesting. The oil filter has spiralled, like someone had wrung it out. So new oil, new filter and still oil light flickering, it turned out the oil strainer in the engine pan was completely clogged with the remains of the inside of the oil filter, Filter looked ok visually from the outside except for the spiralling of course but the inside must have just disintergrated. Cleaned the strainer and that engine is still going today and is well over 200K.
If all else comes up dry I'd suggest having a look at the strainer just in case.

[bender01]

200k!! I think you need to start a thread of whos got 200k! and it has to have pics!! Really. Start one. I cant.
  Oh yeah, Welcome!
 Ben

[Popwood]

200K miles!!?? Holy cow. Let's here more about this. And do start a thread as suggested. But getting back to that milage, are you original owner? Tell us about bike history...how it's been maintained, oil used, service routine. I've read about 100K bikes before rebuild, but 200K is a new chapter.

[Oddjob]

Sorry forgot about this.

Well a little history, I have a few 500-4s, some have more history than others. My first one and the subject of the thread topic was bought second hand in 1973, it had 13k on it then and was a 1972 model, it had just returned from a european trip around Spain, hence the high mileage for what was a year old bike. I met the previous owner and got some info about the bike off him, he'd just bought a brand new 500-4 to replace it as he said the price was great so he couldn't resist.
I lived on that bike for about 5 years, rode it everywhere in ANY weather, I put the 100k up by 1978, however useage tailed off as I bought a car but I kept it for a long time until my brother in law bought it off me, by which time it had 140k on it. He put the 200k up by 1985, engine has been apart a few times, mainly to replace primary chains but the pistons and barrels are still original, rings have been changed though, not because it was burning oil as it's never smoked at all in it's life. The entire top end is still original, new stem seals is all that's been done. Gearbox hasn't been touched, clutch is original, never changed the plates. Odd when I think of that as I did thrash the bike unmercifully, even raced it and the clutch still keeps working great. It's had a couple of push rods, 3 primary chains, 1 camchain, never been shelled or had a new bearing. I'm an ex Honda mechanic and the bike was constantly maintained, no expense was spared and hours were devoted to keeping the engine in tune. Had my own vac guages and strobe light.
The bike now is barely used, everyone in the family can use it and it's in really good nick considering, it has around 260k on it now, last rode it about 2 years ago as my brother popped over on it and I couldn't resist having a blast on it.

[Oddjob]

One of my other 500-4s is also over the 100k mark, I have a fully restored 1973 model which I spend a bundle on restoring, that has approx 160k on it, it had 45k on it when I bought it, rusting in someones back yard and hadn't moved for 10 years. I restored it and put all the other mileage on myself, still have that one in a garage but it hasn't moved for a while now. Partially dismantled for another restore, however I did fire it up one day, hadn't been touched for years and I just put petrol in it, jumped a car battery onto it and it started first time. Even rrode it down the street with no exhausts on and no seat 

I'm riding a brand new CB1300 at the moment and I'm enjoying that so much the 500 has taken a back seat, I do however have a loft full of brand new bits for it waiting to go on, new set of 4 into 4 exhausts, brand new original seat, set of Lester wheels (love those wheels, shame they don't still make them) electronic ignition so I can stop having to strobe it every few weeks.

I have quite a few pics of this bike whilst it was being restored, however due to the year that was done they are all in film and I need to scan them into my PC and for reason I never seem to get round to that. Must do it as the engine was a work of art when it was done, all the outer casings and carbs were chromed, the engine had been stove enamelled and it looked and sounded awesome.

[MoMo]

Welcome, oddjob.   Cool stories, shows how routine maintenance prolongs the life of a bike, especially pistons and cylinders...Larry

[thehammer]

i found that the relief valve in the oil pump of my 75 550 was siezed, causing high pressure. valve is under the lower cap on the pump, it should move freely. if not you can heat it up with gas, and pound it out with a punch. sand it down till it slides back and forth nicely, and reassemble.

it turned out the oil strainer in the engine pan was completely clogged with the remains of the inside of the oil filter, Filter looked ok visually from the outside except for the spiralling of course but the inside must have just disintergrated. Cleaned the strainer and that engine is still going today and is well over 200K.
If all else comes up dry I'd suggest having a look at the strainer just in case.

I saw this in a saturn lw300 the other day at work, with the filter twisted to hell. I believe it had been 7000 miles since this customer's last oil change, and the topend was clacking loudly.