Engine oil use?

[Nurse Julie]

At least you tried the basics Bradders. The compression readings were very good on my 400/4 but, when I stripped the engine and found 3 pistons and rings with serious damage, it was actually the carbon build up that was stopping oil getting by the rings and the carbon build up also helped maintain the good compression. Not saying your engine has such substantial damage and issues that mine had but....worth bearing in mind.

[Bradders]

That’s interesting Julie. Hadn’t thought about that. Steve I’ve been into Hatfield’s a couple of times but they said that they would do MOT’s but that was about it as my bike was too old! Maybe I’ll try them again. Chris.

[SteveD CB500K0]

Has the old guy retired then?

2nd try would be Gary Beresford at GS Motorcycle Tyres (or “Bike Base” ) in Winnersh.

He’s put tyres on my 500s and now has an MOT workshop and does mechanics as well.


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[Bradders]

Thanks Steve. I shall try him.  Thanks.

[Bryanj]

Just come to this party, oil consumption is way too high and must be going somewhere. Did you decide if it was smoking?  I would suspect valve stem seals first and pistons second.

[Bradders]

Hi Bryanj. It doesn’t smoke on start up and my wife has followed me in the car and she says she couldn’t see any smoke.

[Nurse Julie]

So if it's not smoking that only leaves 2 possibilities. 1) Oil leak. 2) You are riding it flat out in the red in every gear for 200 miles 🤔🤔🤔

[Bradders]

There’s a slight leak on the fins. Maybe I need to get my wife to follow me again and I’ll  give it some welly to see if it smokes. Do you think it would be worth me putting some more Redex down the bores? Have done it once would there be any benefit to doing it again?

[Nurse Julie]

Get Mrs Bradders to follow you again and ask her to look for smoke on hard acceleration and also on the over run (throttling off). Also, when you pull up, see if she smokes at idle. I don't see the benefit of more Redex at this stage personally. You say small leak on the fins, whereabouts?....rocker cover area or cylinder head area or barrels area, or is it difficult to know where it is coming from precisely?

[Bradders]

Hi Julie. I think there’s a slight leak between cylinder and cylinder head also the rocker spindle cap and some of the oil sump pan bolts. Would that be enough to lose so much oil?

[Nurse Julie]

It will definitely contribute towards high oil consumption. If you see signs of a leak, oil over casings etc, that could just be the residue that's left after a ride, you may well have quite a bit of oil loss when riding but you won't see it as its been blown off the engine whilst riding. You say there is oil leaking from the sump but that being at the lowest point, that is where it is going to end up. It could br the oil pump, the gear change spline seal or/ and the starter motor O ring leaking or the clutch gasket or kick start seal on the other side. I changed my sump gasket twice a few years ago due to a leak, made no difference as it was the starter motor O ring that had perished. It may be worth you investigating these things next. A combination of oil leaks and burning a bit of oil, which is quite normal for an old engine, could well add up to your combined oil loss. Also attend to the rocker spindle cap leak.

[Bradders]

Thanks Julie. Now you mention it there’s some oil near the kick start as well. I think I need to find a mechanic to have a good look at it as I’m not a mechanic by a long shot. Thanks for your advice Julie.

[Nurse Julie]

Good idea. It is nothing unusual for O rings / seals to be perished on bikes that are 45 years old. They go dry and brittle and just don't do their job any more. Even if you can change, or get someone else to change all the easily accessible parts, it would be a huge step in the right direction. After changing them, if the head gasket is weeping a little bit, I wouldn't worry too much about that. I know yours is a very early engine and head gasket leaks were very common. You need to stem the flow of all the easily doable bits first though.

[Bradders]

Thanks Julie. Ive left a message for a mechanic to call me back. He has been recommended to me by SteveD so hopefully he will be able to help me.

[Bradders]

Thought I would update this post. After having new valve stem seals and rings fitted it seems to of cured the high oil consumption I was experiencing. Have done 300 miles since the work was done with no oil loss, before the work it was burning about 1/2 a litre every 200 miles. So thanks to everyone’s advice.