Heavy "smoking" but confused - and Compression is really high.

pbboxer

pbboxer

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Hi all,

I've had by TC Triple Black for a number of years now and it's been regularly serviced and ridden progressively but not hammered by any means.

I was in the Isle of Man a few weeks ago camping with the family and didnt get to ride much at all. The one day we did get out, my son advise me that the bike was smoking but that it cleared in a few minutes.

Back home, checking the bike on the centre stand, when ticking over it sounds as good as it ever did - smooth and quiet.

If revved in a hard blip, the bike puffs grey smoke, lots of it. Riding on the road it seems to be pretty clear on a normal ride but i've obviously stopped riding and am trying to diagnose the issue.

Compression seems very high in both cylinders. Checked today and both reading 215 (yes the throttle was opened at the time)

The smoke as such, smells more of fuel than anything.

Oil level wasnt peak so i've run the bike to temp and got the oil level right for reference after a few minutes cooling - maybe added 300ml

I've checked the air box in case the bike had been over filled and was dragging oil through, but its clean

Plugs look "ok", slight darker than ideal but not sooty or black - dark but no bad.

Thinking maybe fuel pressure regulator - this has come on suddenly but I'm definitely concerned about why the compression is showing so high also.

Advice appreciated!
 
Very occasionally mine will chuck out a big blue cloud of oil smoke on startup if it has been left on the side stand. It clears after a minute or two and won't happen again for months. It's just oil getting past the valve but doesn't sound quite like your symptoms
 
Is this with the same fuel as when it first started? Perhaps it may be contaminated fuel, if your mechanical results are coming back as fine.
 
If you have your bike outside in a campsite it could well be just a little condensation, just steaming off!
If it doesn't happen all the time I wouldn't worry about it.
 
MILLE_RIDER said:
Very occasionally mine will chuck out a big blue cloud of oil smoke on startup if it has been left on the side stand. It clears after a minute or two and won't happen again for months. It's just oil getting past the valve but doesn't sound quite like your symptoms
Click to expand...
Hi. Yeah had that on my old 1150 a couple of times but this started very suddenly and persists when on centre stand and given a squirt of the throttle. It doesnt stop
 
DJ123 said:
Is this with the same fuel as when it first started? Perhaps it may be contaminated fuel, if your mechanical results are coming back as fine.
Click to expand...
i've added new fuel since but thanks for the suggestion
 
GORILA said:
If you have your bike outside in a campsite it could well be just a little condensation, just steaming off!
If it doesn't happen all the time I wouldn't worry about it.
Click to expand...
Thanks. Yeah it's doing it and not going away sadly. A handful of throttle blip and it's chucking it out badly. It's not stopping within a few minutes at least and does smell of fuel but looks like oil grey
 
Can I ask a few questions? They are just the ones coming to mind. I have been through my own bike recently and I kept jumping to conclusions about things...

Is the fuel clean? You sure??!!!

Does it live on the side stand? Saying that, mine blows a cloud on occasion but clears up when up to temp...

You say the compression is very high. Have you measured it before now? Is this defiantly new?

Would you say something has failed or something is new?

Just offering support and suggestions.
 
A change of valve clearances or timing can affect the compression figures. Take the head covers off and check the valve clearances. Also check the inlet/exhaust cams are aligned when that piston is at TDC - for checking you don't need the tool, just use a straight edge down the flats on the ends of the camshafts.
Screenshot 2026-10-04 at 22.06.23.jpg

If it wasn't for the high compression figures I'd suggest checking the air filter and the intake air path.
It could also be a faulty temperature sensor for the cylinder head or intake air (assuming your temperature gauge reads ok - if not then check the oil temp sensor)
 
Comfy Old Boots said:
Can I ask a few questions? They are just the ones coming to mind. I have been through my own bike recently and I kept jumping to conclusions about things...

Is the fuel clean? You sure??!!!

Does it live on the side stand? Saying that, mine blows a cloud on occasion but clears up when up to temp...

You say the compression is very high. Have you measured it before now? Is this defiantly new?

Would you say something has failed or something is new?

Just offering support and suggestions.
Click to expand...
Hi. Yes, i believe the fuel is clean and refreshed with definitely good super unleaded that we used in my son's race bike a couple of weeks ago fresh from same can. The bike lives on the centre stand - Over the years ive seen issues with bikes being left n sidestands and having issues with RH cylinder when left running etc. I haven't measured the compression on this bike before. It's good that both sides are similar at least - the gauge i'm happy with as being relatively accurate. I feel that something has likely filed as the smoking has come on suddenly. I'm wondering if it might be a fuel pressure regulator or similar. In terms of oil use, ive jus topped he oil to the right level and the only way i'll know if the issue is burnt oil or fuel, is to ride for a while i guess, but i'm loathe to do so in all honesty. I really appreciate the feedback, thanks.
 
Fifth Horseman said:
A change of valve clearances or timing can affect the compression figures. Take the head covers off and check the valve clearances. Also check the inlet/exhaust cams are aligned when that piston is at TDC - for checking you don't need the tool, just use a straight edge down the flats on the ends of the camshafts.
View attachment 543973

If it wasn't for the high compression figures I'd suggest checking the air filter and the intake air path.
It could also be a faulty temperature sensor for the cylinder head or intake air (assuming your temperature gauge reads ok - if not then check the oil temp sensor)
Click to expand...
Thank you, will look at this
 
I cant help but feel that your compression reading is off. With a compression ratio of 12.0:1 the best you could ever hope for is 160 psi, assuming that psi is what your gauge reads.
To get 210psi you would need a compression ratio of 15.5:1...
 
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