Topic: CB750 k2 oil light issues

[Metalmicky]

Hi
I’m thinking of buying  a CB750 k2 but the seller is 300 miles away.he tells me the oil light sometimes comes on at idle and it’s a common fault? Is this true please

[seanbarney41]

I wouldn't say it is common.  It has been reported here many times.  Can be caused by several things that don't necessarily mean that the engine needs rebuilt.
    -Pressure switch is dirty/clogged/faulty
    -Wrong viscosity oil or extremely worn out oil
    -Oil pump problems such as leaking seals/o-rings or worn rotors
    -all these symptoms could be made worse by idle speed set too low

[PeWe]

Idle of 1200 rpm should work fine without oil pressure warning. Oil 20W-50 for motorcycles wet clutch.

[BenelliSEI]

My K3 did this when hot (and idle stumbled a bit low). Installed a new sensor, no more problems. I have an oil pressure guage on a few of my cb750s, and they do dip pretty low, at idle, after a long run.......

[PeWe]

My K6 could get flickering oil light when really hot despite refurbished pump and restored engine with fresh crank bearings.  A really hot summer mostly +30C when I gave it Red Line 20W-60 to keep the viscosity in healthy status and avoid oil warnings. Temp in oil tank 110-120C (230-248F)

Pump got new rotors made by MessnerMoto that improved a lot.

My K2 build got those rotors too.

[Nurse Julie]

If you're in the UK like me, we rarely have temps above 30° so I wouldn't worry about that 😀😀😀 Maybe ask the same question on SOHC.co.uk and see what replies you get. I have only had that problem one on one of my SOHC/4's, it was the oil pressure switch. But, it could be anything from minor to major.

[PeWe]

UK must have had a hot 2018 season as we had in Sweden, right?
If pump keep oil in tank, a quick oil upgrade can be done by let oil in pan out. Refill with 20W-60, around 1 bottle.

[Nurse Julie]

UK must have had a hot 2018 season as we had in Sweden, right?
If pump keep oil in tank, a quick oil upgrade can be done by let oil in pan out. Refill with 20W-60, around 1 bottle.

Yes, 2018 summer season was great and hot across most of Europe for extended periods...but I still didn't have an oil light come on at anytime other than when it was meant to and I only ever use 15w40. Even this year at 38.7°, bikes were still fine.