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Author Topic: Smoke Gets In My Sushi...!  (Read 254 times)
ModerateFkr
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« on: July 02, 2017, 12:00:29 AM »

Okay, I've discovered that my Japanese CB-1 engine is smoking very badly when revved - even when hot! Not at all happy.

23,000km on clock (16,000 miles) supported by all MoTs from when it was first UK registered, and passed through four or five owners all apparently doing very few miles. The story is that it was imported by someone who was going to start a training school, but it didn't come off.

All the original engine bolts are intact and apparently unworked. Lots of road dirt but no signs of abuse. Possibly two small drops. Tank and tail have been resprayed. Tail has been repaired where it connects to side panel.

Only bought this bike very recently and not got it on the road yet due to other matters. The smoke issue has got progressively worse over last few times I've started it. All I've done is let it warm up and run the revs up to 3-4k occasionally. The fan has come on eventually. It sounds okay, but may be hunting a little.

Yesterday I discovered that the PO overfilled it with oil, so I thought oil was getting past the rings. I drained a full 500ml off (by tipping the bike over to the right), bringing the cold level down to MAX marker line with filler cap resting on thread.

But that didn't cure it. Still smoked.

Also, when the engine is running, there's some pressure in the sump. Is that normal? Does the cam gear drive train create sump pressure?

Does the normal downward progress of the pistons cause sump pressure? I don't recall if it did on my other bikes - a million years ago.

But, I thought it could just be bad fuel. So I checked that before assuming anything, or planning any major work.

Drained off some and it was light PISSYELLOW! Anyone seen yellow unleaded petrol in UK?

It also turned cloudy PISSYELLOW after a few minutes in the clean aluminium foil baking tray!! That surprised me. Rather supports the additive theory.

So I drained carbs by running it to stall. Then I drained the tank completely. Removed it, shook it about until there was nothing left. Inside seems clean, no rust, and filter seems to be intact. Even discovered how to turn it to OFF.

Replaced the tank and refilled with 6 litres of Sainsbury's unleaded.

Still smoking! But it was dark by then so I'm not sure if it was as bad.

One theory:
PO may of course have added a bore treatment to disguise a worn bore or broken ring issue, and added the oil to mitigate for the effect/loss. Wouldn't be the first to do that.

Certainly looks like a possible ring issue to me. That definitely would cause sump pressure AND oil in the combustion chambers.

There's a constant plume of light smoke that smells of oil - I think. But I've never actually seen blue smoke, so I'm not sure. The smoke increases noticeably when I rev the engine. I believe that suggests rings rather than valve or valve guides. Am I right?

No, I haven't revved it hard whilst cold. I can't actually hear anything odd in the engine, but I haven't applied a wooden listening dowel to it yet.

Whilst tank was off I removed the very stiff and difficult to access radiator cap (between snorkels). The thickish green coolant was right up to the top. There's no hint of white in the oil. No froth or milkiness.  

Next I need to remove the plugs. I'm sure you all know why I've delayed that task. I believe they're rather tricky to get at...!

But now I have to remove the half full tank to get at them. We find creative ways to punish ourselves for our decisions! ;-)

Any wisdom anyone can offer will be greatly appreciated. What have I missed? What other tests do I need to carry out? How accurate is my diagnosis thus far? Anyone else had this issue? What course did you take?
« Last Edit: July 02, 2017, 12:05:59 AM by ModerateFkr » Logged
a_morti
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« Reply #1 on: July 02, 2017, 08:26:19 AM »

It's quite normal for an internal combustion engine to have pressure in the crankcase due to pistons going up and down. If the bike was overfilled with oil it could have blown some up into the airbox but it seems unlikelyto get from there into the combustion chambers.

Burning oil could be piston rings or valve stem seals. Piston rings show more on revs, valve seals more on start up as the oil in the rockers has a chance to drip down. Either case will show as low compression so a compression test will tell you which cylinder is down and how badly.

If i was guessing I'd say valve seals as they can go hard with age particularly if not used much.

Sorry to hear this Sad
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Cam Drive Gear Train Smiley
ModerateFkr
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« Reply #2 on: July 02, 2017, 10:37:07 AM »

It's quite normal for an internal combustion engine to have pressure in the crankcase due to pistons going up and down. If the bike was overfilled with oil it could have blown some up into the airbox but it seems unlikelyto get from there into the combustion chambers.

Burning oil could be piston rings or valve stem seals. Piston rings show more on revs, valve seals more on start up as the oil in the rockers has a chance to drip down. Either case will show as low compression so a compression test will tell you which cylinder is down and how badly.

If i was guessing I'd say valve seals as they can go hard with age particularly if not used much.

Sorry to hear this Sad

Thank you a_morti. Useful advice.

Just one more thing I didn't need to be dealing with. Had a council tax debt collector trying to steal it last week!!! The debt didn't exist because the council failed to correct their records. But that's a 'clerical error' with zero consequences. All they have to do us make a false claim and fail to correct it, and I have hours of legalshit to deal with. They even withdrew a summons and cancelled a hearing, but still billed the 'court costs'. We Brits are idiots for putting up with this corruption.

Anyway, just a little context.

Later.

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Dash
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« Reply #3 on: July 02, 2017, 12:45:00 PM »

It's quite normal for an internal combustion engine to have pressure in the crankcase due to pistons going up and down. If the bike was overfilled with oil it could have blown some up into the airbox but it seems unlikelyto get from there into the combustion chambers.

Burning oil could be piston rings or valve stem seals. Piston rings show more on revs, valve seals more on start up as the oil in the rockers has a chance to drip down. Either case will show as low compression so a compression test will tell you which cylinder is down and how badly.

If i was guessing I'd say valve seals as they can go hard with age particularly if not used much.

Sorry to hear this Sad

Thank you a_morti. Useful advice.

Just one more thing I didn't need to be dealing with. Had a council tax debt collector trying to steal it last week!!! The debt didn't exist because the council failed to correct their records. But that's a 'clerical error' with zero consequences. All they have to do us make a false claim and fail to correct it, and I have hours of legalshit to deal with. They even withdrew a summons and cancelled a hearing, but still billed the 'court costs'. We Brits are idiots for putting up with this corruption.

Anyway, just a little context.

Later.



Not just you brits. If thats any consulation.

on topic: could it have something to do with a rotten head gasket?
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Efreeman55
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« Reply #4 on: July 02, 2017, 01:40:24 PM »

As Morti said, get a compression test before doing anything else.  I have 20,000 miles on my 1989 CB1 and it doesn't use a drop of oil between changes.

Eric
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ModerateFkr
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« Reply #5 on: July 02, 2017, 02:13:04 PM »

Thank you Dash and Eric.

Compression tester is on my buy list.

There is always the potential for issues with small liquid cooled alloy engines isn't there? I recall that Honda rather cleverly limited those issues to the head gasket on the CX engines. But how can you tell if the head gasket has rotted if there's no coolant in the oil or oil in the coolant?

Will also be looking at the air filter. I'm also considering getting an endoscope of some sort. Costco had a good one a while back. Should have grabbed it then.

The only reason for mentioning the legalshit is to put this smoke discovery into correct perspective. Most single instances of adversity can be handled - with a little help from our friends. But two, three, and more issues at once tend to reduce the quality of life unreasonably.
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ModerateFkr
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« Reply #6 on: July 03, 2017, 08:08:52 PM »

UPDATE

I've been making enquiries about engine treatments designed to stop smoking. There are a number of fuel additives. The place I went to admitted that people regularly request a product to add to a vehicle they're trying to sell!!

All these products are very similar. They're thick gloppy liquids. Guess what colour they all are...?

Yep, PISSYELLOW!!!

Busted.

Now we need to get legal.
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Dash
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« Reply #7 on: July 04, 2017, 02:47:24 AM »

UPDATE

I've been making enquiries about engine treatments designed to stop smoking. There are a number of fuel additives. The place I went to admitted that people regularly request a product to add to a vehicle they're trying to sell!!

All these products are very similar. They're thick gloppy liquids. Guess what colour they all are...?

Yep, PISSYELLOW!!!

Busted.

Now we need to get legal.

Guess you ll be cleaning a lot of fuel hoses, carbs etc...

Maybe get some Forte carb cleaner etc.
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ModerateFkr
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« Reply #8 on: July 04, 2017, 09:24:22 AM »


Quote

Guess you ll be cleaning a lot of fuel hoses, carbs etc...

Maybe get some Forte carb cleaner etc.

Indeed Dash, but for now it's evidence!

If someone sells a motorcycle having disguised a known problem that could cause catastrophic engine failure, that could cause the bike to seize, which in turn could cause serious injury or death, that person has committed multiple serious offences.

Next stage is to do a compression test in an attempt to verify the true nature of the problem be disguised and concealed in his offer of sale.
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