If you correctly diagnose the problem, I'll send you a genuine MV Corse carbon fiber key guard for an F4.
Bike was running fine after the chip replacement. It started this morning as I was loading it onto the truck and died. Never started after that. It turns over, it won't catch.
There is spark.
There is fuel.
The ECU is fine, I tested it on another bike.
The TPS was cracked, from my leaning the bike against the door jamb, probably, but I fixed it. I even replaced it with another one and still no joy.
Ask as many questions as you like. This issue has me stumped.
I took some fuckitall and gave up. I'll pull the engine out of the frame and tear into it. Not in the near future, however. I'll be doing moving stuff.
So here are pictures of the cylinders and cylinder head. I have no idea why piston #1 looks brand new, and all the others have some carbon on them. I don't see anything unusual.
Also pictures of the head. I don't really know what I'm looking for but it doesn't look horrible.
I suspect piston 1 was changed at some point recently, maybe something bad happened. It is a little hard to tell with the pictures, but what is up with the intake valves of the adjacent cylinder. In the pic, they look beat to shit? Maybe detonation damage? I would probably take the head in and have a valve job done, since you are to this point already. Replace any suspect valves.
I should probably pull the valves out as Lee suggested, but I don't have a valve spring compression tool. Any suggestions? Noel said something about one Honda makes.
The lid had to come off anyway Ed so whatever may be diagnosed in a leak down test in this case would still have resulted in the head coming off.
I wonder if the cam chain adjuster has been replaced for whatever reason? By rights with the few miles "Apparently" it has recorded I wouldn't have thought it should, but if it has for what ever reason it has been it could be that the cam chain jumped a tooth or two initially and slightly bent some valves, possibly in this scenario who ever did the work may have thought they had got away with it.
The valve stems on the SPR are very delicate indeed.
I have a gut feeling this bike has been seriously tracked.
To the casual observer it looks like a new piston . This would suggest that the cylinder could have previously overheated and the rings picked up on the bore. It looks as though the bore may have been re- bored/re-honed and and o/s piston and ring set put in ?
It then begs the question , were the other three bores / pistons compromised. ? Has the potential overheating suspected, damaged the valves and guides, cracked the head; etc etc etc.
But then that is a casual observation.
If this were mine I'd have a complete strip down and inspection measuring bores for ovality as well as diameter...with a full engineering inspection of the cylinder head / valves .
In fact if I were going to keep the head as I don't have the engineering experience I'd give it to a specialist I trust. I may even balance all and decide it is more cost effective to replace with a good used set up
It's not a happy bunny...
In situations like this I am very curious to understand the cause and keen to do the work myself but sometimes I just let the boys who know step in and make it all better again.
I've just asked the boys on Laverda forum for an assessment of this as it stands..They are used to cracked cylinder heads/ bore issues as the bikes are 30 + years old .. ; ) Be interesting to see what they think
How can you tell the valves in #2 have been hitting the piston? They look like all the other valves. I've taken another picture of them.
Ed, I did spray that stuff you recommended into the engine. The carbon deposits on top of all the pistons except #1 will wipe off with a swipe of a cloth. The are not caked on there. I don't know if that makes a difference.
I didn't have a leak down tester, so I fashioned a tool that allowed me to blow compressed air into the cylinder. I could feel air blowing up into the manifolds. If I pressed my hand over the manifold and tried to seal it, it could be done but required some force. Then the air would blow up the valve guides.
The usual indications that someone had been in the engine are not there. All wires were in place and uniformly covered with dust and the usual grime. The colors of everything was pretty uniform. Nothing looked new or out of place or just replaced. There was no gasket goo anywhere.
I changed the oil before I sprayed in the power tune, knowing I would have to change it again after the process.
Also, I'm not sure this makes a difference, but just for grins I did a compression check of cylinder #2 before I pulled the head off. Throttle body removed, plugs in every hole except #2. Plug wire to #1 also disconnected. The engine caught for a moment, ran on two cylinders (3 and 4) and died. Compression reading was 175psi.
G,day Cag , I,m not an electrical wiz like some of the boys here and have just come into this thread without reading all the other 10 or so pages.
what I can offer is very good mechanical experience so here is a simple thing to try to check your valves are seating well.
just make sure the respective cylinder has the valves on the back of the cam ( valves completly closed no cam lobe contact ) .
turn the port so it is facing to the sky and pour enough kerosine down the port to cover the valve heads. If you see the liquid coming out through the valve face you can easily assume the seats are u/s.
Old, quick test to grasp an early indication of seat conditions.
as I said before I have only read a few pages so if this has been covered already sorry for wasting your time.
Based on what you have told ma Carl I'll bet you a Beef Chop Suey that you have some bent valves in there.
Why they are bent you'll never know, I'd hazard a guess that its possibly had a camchain issue in the past and the valves have very gently kissed the piston, not enough to show evidence on the crown of the piston but just enough to bend the valve stems though.
I accept the valves are moving up and down, but if the stems are slightly bent the valve guides will wear abnormally allowing the valves to slop about on their seats and you'll loose compression.
From my understanding you are experiencing compression and suction within the rocker cover indicating there is an issue with the valves and valve guides.
My money is deffo on the valves being bent!! Reason unknown!!
I must have numbered the cylinders wrong. I was referring to the intakes next door....the ones that appear silver around the perimeter of the valve head as opposed to black.
Sounds like the power tune started the cleaning process, but the engine wouldn't run long enough to finish it. Perhaps that is why the one piston looks so clean. That stuff really does work well at removing carbon and deposits.
Your make shift leak down test shows the intake valves are not sealing. As Triple recommends: Take some parts cleaning fluid and fill the intake and exhaust ports. None should leak past the installed valves into the combustion chamber.
It's top end overhaul time.
I have diesel fuel leaking past the intake valves on cylinders 1 and 2. A tiny bit is leaking past one intake valve on 4. I pulled one of the valves out and spun it in the lathe. It is badly carboned, but doesn't look bent.
I will clean the other valves, re install them and repeat the test. I'll have to find the specs for the valve springs as well to see if they have perhaps collapsed.
Pics soon of dirty intake valves and clean intake valves. Maybe even a video of one spinning in the lathe!
Glad that you have identified a possible problem Carl
I was thinking that I should have mentioned to check if there much side to side movement in the valves when they are installed?
Either way the entire head needs a good looking at for sure, providing the valves aren't bent and the seats are good all the valves will need 'lapping in' and new stem seals fitting.
The advice so far from the Laverda boys is that the clean piston could well have been cleaned by conditions in the chamber and not necessarily replaced. For example if the head gasket was blown it would steam clean the crown of the piston..
Yes! A blown/leaking head gasket will do that as will piston rings that are passing oil, a clean edge around the circumference of the piston is a good sign the oil rings are not doing their job.
On the picture of the block/pistons is it just a trick of the light or do cylinder numbers 1&4 look at slightly different heights?
There was a friend of mine a while back (more years than I care to remember!) who developed a carbon cleaning system, basically just a water vapour injection, he sold the patent to one of the large company's like Wynnes (or similar) never got put to use though, I think they just bought it to get rid of him and the product!
Pretty common to clean carbon deposits from large marine turbochargers with water or steam injection, walnut shells (of all things) are used too. Wouldn't recommend filling your tank with walnut shells though. :wtf:
So the saga ends. I apologize to whoever it was who guessed bent valves first. They didn't look bent. They moved up and down just fine. Even removing them, cleaning them, and spinning them in the lathe didn't reveal anything. They looked fine. It was only when I couldn't get the damn things to seal that I suspected something was wrong with the valve seat or spring pressure.
The valves are not bent as much as they are warped. I did not see this no matter how many times I looked at them. It was only when I put them on a flat surface, and I mean dead flat like one of those machinists base plates and rocked the valve could I see it was slightly warped. Not bad enough to make the engine not run, it ran fine on the dyno, but bad enough that the bike ran like crap at low RPM..
So the saga ends. I apologize to whoever it was who guessed bent valves first. They didn't look bent. They moved up and down just fine. Even removing them, cleaning them, and spinning them in the lathe didn't reveal anything. They looked fine. It was only when I couldn't get the damn things to seal that I suspected something was wrong with the valve seat or spring pressure. So I changes springs on intake valve one cylinder one. Problem solved. Valve nicely sealed. It was only after I changed springs in the other valves and they still leaked that I took an even closer look. I inserted an old intake valve from blown SPR engine in valve two cylinder two and that one stopped leaking.
The valves are not bent as much as they are warped. I did not see this no matter how many times I looked at them. It was only when I put them on a flat surface, and I mean dead flat like one of those machinists base plates and rocked the valve could I see it was slightly warped. Not bad enough to make the engine not run, it ran fine on the dyno, but bad enough that the bike ran like crap at low RPM.
This was a fascinating and educational experience for me. Luckily, this is a parts bike so I don't really care if it needs new valves. I'll put them in when I get some, or I'll part it out or use if for spares.
Very unusual for inlets to get bent, in all my time with over revved race engines it was always the exhaust valves, and if your ever messing about try this:
Leave the inlets out and time it up with just the exhaust cam, watch the piston/valve through the inlet vlave hole...............it will scare the s&*t out of you and you will never ever red line anything ever again:jsm:
The exhasut valve is going down the piston is coming up on what looks like a massive accident, then with around 2mm to the crash the exhaust valve changes it's mind and goes back up!! scary stuff
its tough to bend a valve without some kind of contact. If its not from jumping timing then it could be from a mechanical over rev or extreme carbon build up.
The bike was a real rat. Looked like it had been sitting outside for all of its 8 years. I would assume the 3400 miles is correct. The bike didn't look beat on, just neglected. Here is a picture of the bent valves.
One of the differences between SPR valves and stock 750 valves are the SPR valves are necked down after they leave the guides, and they are dished, like the exhaust valves. The stock 750 valves have a flat face on them.
I've seen plenty of bent valves in these engines and they always bend in the same place. Between the back of the seat and the guide. Exactly where you would expect. These three valves are so much bent as warped. If you expand the picture and look very closely you can see they are not sitting flat on the plate.
What it looks like is the back of the valve, the part that seals against the valve seat, is slightly peened over. So while the valve seals against the seat fine, this one area of perhaps 30 degrees out of 360 does not.
This is great information, Ken. I have a dial indicator and I will use that to measure concentricity of the valve stems and valve face today.
I don't know when they switched over to the valves with the thinner stems. I know the SPRs all had them, I know the Brutale 750s did not. The diameter of the stems seems within spec as do the valve guides.
Assail; from the beginning, when I first saw the bike there was something wrong with it. I ran rough off idle. The seller said he didn't know why. He said it pulled fine, it just didn't have that clean snap from idle. I had no idea what it was but figured that if the bike started and ran it couldn't be a huge problem. When I got the bike back here it ran like crap until I changed the chip that was in it. Then it ran fine until I tried to load it onto the truck for the trip to the dyno. That's where this thread started.
Yes, I said bent valves because that was the closest description I knew of. Is there such a thing as straight valve stems but warped face? Or peened over valve seating surface?
Perhaps a well nut got sucked in and got trapped between the valve and it's seat. Not bad enough to bend the valve, but bad enough to deform the surface of the valve where it meets the seat?
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