KH Over Oiling - a different question

[SteveHands]

Hi All.
Hoping someone can shed some light on this.
My KH500 smokes as though it's wet-sumping permanently.
To side-step any answers about rocker-gear over feed, please note that my engine has all the fixes for that, i.e:

• Restrictor in the rocker feed
• Club tappet guides with larger drain channels
• Valve guide oil seals

It also has rebored barrels and new pistons/rings.
Oil return flow appears normal.
Oil pressure is good, >90psi when cold settling to 25psi warmed up.

I have tried a couple of thing in order to diagnose the issue:

• Disconnecting the rocker feed, in case the usual fixes haven't worked, and drip feeding the rockers manually
• Bypassing the Morgo filter in the return feed in case that was restricting flow
• Temporarily adding an electric return pump via a banjo bolt in the sump plate drain, in case the return pump is weak

None of the above altered the smokiness

I've also tried running total loss and letting the oil just fall out, by removing the sump plate completely, again in case the return pump is weak. Strangely, almost no oil came out until I stopped the engine, at which point it poured out. Now this may be because the engine is breathing through the large hole and the updraft, coupled with the centrifugal action of the crank, is keeping the oil away from the aperture. The same might have also been true with the electric pump connected because that seemed to flow much less than the return pump.

It basically looks like there's far too much oil in the sump or just splashing around and it's getting past the rings, so much so that burned oil is dripping out of the left exhaust joint. Surely that much oil can't come from the valve gear. Even if the seals weren't working you'd only get a slight blue haze. My race bikes have much slacker valve guides and no seals and they don't smoke at all.

What would happen if the pressure relief valve was stuck closed or not bypassing enough? Normally the excess oil bypasses into the timing chest and drops into the crankcase, whereas if that path was blocked, would there be massively excessive spray out of the big ends onto the bores which the scraper ring can't cope with?
The Ariel KH handbook states that the pump can deliver 4 times more oil than is required, so if all of that is spraying out of the big ends could that be it?

Has anyone else had this issue, with any model?

All suggestions and comments welcome!

[Paul Slootheer]

Steve, if I read everything correctly, you have done quite a bit to reduce smoking from the engine. I once did own two KH’s but never did experence what you are writing…
However, you mentioned new pistons and rings, which might be the cause: A: new rings take ‘ages’ to bed in due to modern oil nowadays. B: are you shure the oil control rings are still ok and not damaged? (One can brake with ease a oil control ring when lowering the barrel over the pistons I know from experience…)
It’s looks your oil pump is allright with 90psi pressure when cold and 25psi warmed up (idling?) and a normal oil flow back to the oil tank.
Paul

[nevhunter]

Would it be worth trying to adjust the Oil pressure a bit lower. say 45 psi? any comments? Nev

[Paul Slootheer]

Both my KH’s gave aprox. 90psi ‘stone cold’, but once warmed up under riding conditions it stayed on aprox.65psi and idling 20-25.This was done with a mod with all oil pressure to the mains and top end oiling from a bleed of the return. The problem on the top end is caused by the fact that most, if not all, rockers and spindles are worn which enables the oil to escape far to easy. There’s quit some oil pressure upstairs which in the end seems not necessary. A bleed from the return is more then enough, the same Triumph did on their twins.

[SteveHands]

Both my KH’s gave aprox. 90psi ‘stone cold’, but once warmed up under riding conditions it stayed on aprox.65psi and idling 20-25.This was done with a mod with all oil pressure to the mains and top end oiling from a bleed of the return. The problem on the top end is caused by the fact that most, if not all, rockers and spindles are worn which enables the oil to escape far to easy. There’s quit some oil pressure upstairs which in the end seems not necessary. A bleed from the return is more then enough, the same Triumph did on their twins.

Hi Paul. Did you add a restriction to the return to create the pressure for the rocker bleed, if so what size?

[SteveHands]

Steve, if I read everything correctly, you have done quite a bit to reduce smoking from the engine. I once did own two KH’s but never did experence what you are writing…
However, you mentioned new pistons and rings, which might be the cause: A: new rings take ‘ages’ to bed in due to modern oil nowadays. B: are you shure the oil control rings are still ok and not damaged? (One can brake with ease a oil control ring when lowering the barrel over the pistons I know from experience…)
It’s looks your oil pump is allright with 90psi pressure when cold and 25psi warmed up (idling?) and a normal oil flow back to the oil tank.
Paul

Hi Paul. I’ve put Golden Film non-detergent 20/50 in it. Maybe that’s a bit too slippery to allow the rings to bed. Point taken on the broken oil ring bit fairly sure they’re intact. Strange that the symptoms are exactly the same as with the very worn bores tho. I run the same oil in my Velo and that doesn’t smoke - that has pressure fed rockers too!

[Paul Slootheer]

Steve I made use of a mineral 20/50 multigrade oil. No I did not put on a restriction, I just connected de oil line intended for the cylinder head directly to the oil pressure gauge, and fitted a cartridge oilfilter in the return oil line to the oiltank. I took off a bleed between the pump and the filter. In this way there some very light oil pressure due to fact the oil is forced through the micro filter towards the oil tank. This bleed did lube the head, which was plenty enough.

[SteveHands]

Thanks Paul, I’ll give that a try as I have a Morgo filter in the return side. My feeling is that the rockers should get the filtered oil but yours is the simplest solution.

[SteveHands]

Update: I think the oil pump is fine!

I made up a bench jig with a 'tank' and a 'sump' and drove it with a battery drill. The return flow definitely exceeds the feed flow.

Attached are images of the pump with manifold plate and tank (aerosol lid) and the unit sat in the sump (banmarie tray).

I've also linked videos showing two tests.

'Pump Test Normal' starts with the tank full and a residue in the sump. You can see that once the residue in the sump is pumped into the tank the tank level is maintained and the return side returns aerated oil to the tank. Feed flow is to the manifold plate top surface, the oil then runs into the sump.

'Pump Test Wet-Sumped' starts with the tank empty and the sump full. At the beginning you can see that the feed side pumps bubbles (empty tank) and the return side pumps a steady stream of oil until the sump is emptied back into the tank, whereupon the state in 'Pump Test Normal' is attained.

https://drive.google.com/file/d/17mWNGX ... drive_link

https://drive.google.com/file/d/17gKeyf ... drive_link

So I'll be looking at all other aspects again. It's been suggested I try 'running-in oil' to see if that beds the oil rings in.

[nevhunter]

With NEW Bores, that's not usually a problem . I don't trust the old MAZAK pumps because they can Crack. Check the Oil pressure relief Valve that it does open. 50 Psi should be enough. I personally wouldn't use a running in Oil. I've Reconditioned hundreds of motors and have never used it. The camshaft and followers need good oil Just gradually increase the revs and load you use through the Gears when first warmed up is the way to run motors in IF all the fits and clearances are correct. Nev