Lost All Compression

so, something like this, using with screw in spark plug adaptor? Or to a dial gauge?



And methodology? (should be all plugs out, wide open throttle, and sufficient number of cycles to register max pressure - obviously cranking rpm must be good).

Sorry to ask what might be considered dumb questions....

 

If you can remove the carbs and take a view (small mirror) into the inlet tracs this will also give you more chance to locate the leakage - valves or head/cylinder joint when spinning the motor. Normally exhaust valves go before inlet valves but if the engine has drawn in debris then this could be fouling the seats. As someone has already suggested the air filter could offer some clues. The fact that all cylinders are effected certainly point to something abrasive or gummy going in from the fuel/air side so the fuel tank and contents have got to be suspect too. The inside of the carbs may be revealing.

 

12k miles bike shouldn't have valve clearance issues, so as above are you sure the method/tools used to check compression are sound?
Have you done this before

 

Sorry didn't see new posts!!
Sounds like valve seating issues if getting compressed air in inlet tract. but if one rev out won't be on TDC but intake stroke? do it with cam cover off.

 

Have read this thread with interest
Here’s my take on it
I strongly suspect a fuelling problem 8yrs ago before it was laid up
If this was my bike what I would do is squirt a bit of engine oil into each cylinder
You said you used hydraulic oil I reckon that’s too thin to raise the compression if as I suspect the rings are gummed up after 8yrs they will be
Put the plugs back in and make sure you’ve got good cranking speed with a fully charged battery or jump start off a running engine
Use cold start/ether to assist in the starting
If it does fire up this might free the rings up and will give you a starting point
But it’s only the start of your problems as it had problems 8yrs ago
If it does fire up I would change the engine oil this will help the rings free up and bed in again
The bike only has 12K on it so you should be ok engine wise
Once you get it running properly I would change the engine oil again this time doing the oil filter as well

 

We only know what you tell us and having re-read everything I would just observe that sometimes it pays to have a good think rather than dive in!
Whatever stopped it 8 yrs ago may not be the same as today’s symptoms after sitting idle through the changing seasons and humidity with drying bores. You may have 2 issues: the original, underlying one and a gummed up motor......
Self evidently all the fluids and filters are junk. A cheapie endoscope for $15 will get you into places like cylinder heads and valve seats via the plug hole. With much fiddling you can inspect bores etc. More easily you can check clearance on the heels of each cam lobe and write it all down.....
We don’t actually know what state the injectors are in and whether you once picked up contaminated fuel. The compression issues might just be neglect. See where I am coming from? It needs a systematic elimination approach rather than chasing the latest thought.

 

Good point forgot that in theory unless its got bent valves the compression should be there....clearances could be the problem i would be surprised at gummed rings unless its rust i have see several engines sitting for far longer than that turning over fine and stuck valves usually leave one or two cylinders with compression....not sure about the burnt valve theory after that sort of mileage even without adjustment...but then again its not known if the engine has previously been apart.

 

Missed the new posts....if compression is coming up after adding oil my first question is how much did you add and did you cycle the engine enough to remove most of the oil before doing a compression test?
even stuck and broken rings will respond with positive/more compression with enough oil...however its starting to seem like the rings where stuck not sure of comp ration but if its getting to 125psi i suspect that if you can start it the compression will get back to near normal after a heat cycle or two i would say anything over 160psi should be good.

 

8 year's is a long time for a near new motor to sit un used , the motor may not have fully bedded/run in ! And then running issues , losing power , I'd be with dilli , Need's an assisted start Ether and jumper leads off a good car battery !

When you do it hold the starter button down and crank for a good 10 to 20 seconds at a time , rest for a minute or so and crank again ! Until it fires up !or if you have a rolling road (dyno) available that has an electric motor , tie it down and spin it over in second gear for a few minute's , don't even need ignition on , when you think it might be developing some compression , turn it on and see if it will run.

I've Tow started two bikes , so similar scenario to rolling road ! One took nearly two kilometers at ~40 klms or so to spring the rings loose ! It had sat for 10 or 12 years -1942 BSA 500 single , the other was a Yamaha 850 sat for 20 years , took six weeks soaking the cylinders in molasses and then soaking in mix of diesel and leaded petrol to get it un seized before we could even turn it over !!! Towed that at ~20klms in 3rd gear for a block before it started.

 

Brake fluid down the bores was once the gummed rings solution

Not sure about H&S and COSHH blah blah nowadays issues but have used it successfully. Beware of the volume of smoke created

 

Brake fluid down the bores was once the gummed rings solution

Not sure about H&S and COSHH blah blah nowadays issues but have used it successfully. Beware of the volume of smoke created

 

I've used a small amount of redex left overnight in some (2 stroke) bikes to decoke the piston crown, that may also work (assuming it's the rings that are gummed up)
Now that chucked some smoke out the next day.

 

I just came across this. The exact same thing happened to me, twice, in two Daytonas, years apart. Total loss of compression in all cylinders. I could put the bike on a stand and easily rotate the engine by moving the back wheel by hand in 6th gear.
The first time, I disassembled the engine, found nothing obvious wrong and installed another engine. The second time I decided to just leave the battery connected to a charger and crank the engine for a minute every time I was in the garage. After about 4 days it fired up for a few seconds. The next day it ran normally. I rode several thousand more kilometres before selling the bike. Never found a reason for the loss of compression. Search in Triumph RAT under "Daytona Deliberations", on "Zero to One Compression Ratio" for the whole sad story.
IanB

 

An engine that sits in used for very long time , the rings can become glued or non elastic and then when you need them to spring out and do their job , they don't and you don't get a start up ! Prolonged cranking over or many attempts close together , can sort it out . Or oil such as redEx or castor will boost compression or spring loose the ring's too

 

OK, but both of my compression losses occurred between pressing the starter briefly, firing but failing to settle into idle, waiting a second and pressing it again. The engine spun over very fast but failed to fire again. It was that quick, in all three cylinders. No compression. In each case it was only days since I had last ridden the bike.
I could turn the back wheel by hand in 6th gear and feel resistance 3 times each 2 crankshaft revolutions as inlet valves in one cylinder opened near TDC along with the exhaust valves of the cylinder 120 degrees behind it. Normally the compression in the 3rd cylinder a further 120 degrees behind would stop me moving the crankshaft, but there was no compression.
These engines have no camshaft sensor, only a crankshaft position sensor (CPS), detecting 23 notches in the alternator rotor, one of them twice as wide as the other 22. While the engine is running the ECU uses the CPS to control the injector and ignition coil for each cylinder during the 4 stroke cycle. But the CPS alone cannot tell the ECU if (for example) cylinder #1 approaching TDC is on the compression stroke or exhaust stroke. The ECU works this out during cranking, using the CPS to detect when each cylinder is on the compression stroke (not exhaust stroke) by detecting the crankshaft movement slowing slightly three times each two revolutions. Once the ECU is in sync with the camshaft position (using the crankshaft sensor) it knows where each cylinder is in the 4 stroke cycle. It energises the injectors and ignition coils and allows the engine to start.
With no compression the ECU does not detect the compression stroke, does not get into sync with the engine cycle. The engine spins very fast, but never fires. This was the state of both of my Daytonas, 2 years apart.
With the second one, after much cranking over several days, I heard it pop once or twice. That was good, since enough compression had returned for the ECU to detect crankshaft deceleration on the compression stroke and get in sync, energise the injectors and coils. The next day the engine fired up briefly, the day after that it ran normally. It never failed again.
I know this is hard to believe, and after 6 years I still cannot explain it.
IanB