Corsaro 1200 Year 2007 broken exhaust valve

[Arjula]

Hi!

I bought my bike 2007, new bike.
My bike was run 34000km and now engine was loss power. In long time it was not running well low rpm and quite strong knocking noise was heard on front cylinder. When motor was warm, it didn't start smoothly.
I drive to home and when I was on my home yard, suddenly it shut down and newer start again.
I opened front and back cylinder head covers and measured clearance of valves.
On front cylinder, right side exhaust valve there was no any clearance. all other clearances was in manufacturer specs on all other valves.

I change new shim to it and then clearance was ok. Then I just to want to make sure that there is no any pressure leakage on both cylinders, I crank front cylinder piston to upper level when all valves are closed. Then I took spark plug away and put air pressure to cylinder from spark plug hole. Pressure was going out from exhaust valve to exhaust pipe!!!

I did the same action to rear cylinder and it was ok. No pressure leakage.

So I took cam shaft away from front cylinder and took away the whole cylinder head. Right side exhaust valve was melted on one side. Big metal piece was gone to some place. I think that piece is on catalysator. Nothing happened on piston. There was no any damages on piston and cylinder head.

I pick-up all valves away from cylinder head. The valve seat pipe was also enlarged, so valve shaft could move too easily horisontally x- and Y-direction, that is why also valve seat ring was also bad condition.

Melted exhaust valve

068.jpg (192.64 KiB) Viewed 10780 times

I gave cylinder head to local machine tooling company and they made new valve seat pipe and new valve seat ring and fitted these to new valve.
All other valves was good condition. New cylinder head gasket. Rebuild all parts back to motor.
Now it seems engine runs well.

Only worry about is back cylinder. There is same hearing of that knocking noise coming from back cylinder. It may possible that valve seat pipe is also enlarged, so valve doesn't seat against to valve seat ring properly. I think. So may need to check also back cylinder head also. But now it runs and ready to rock!!!

When 20000km I was run, the bike was in local importer service, so I think that they checked valve clearances. After that it was run 34000 km and this was happened.
Now I am not sure why this happened. What may be root cause of this. I have Termignoni exhaust without dB-killers. So my worry is about does it run too lean on some rpms? I know that valve clearances should check every 10000km, so now in future I will check clearances at least every 10000km.

I think it may help if try to use new ECU map. Have anyone measured in dyno run, does it run too lean which any rpms?

[MonstroMorini]

You were lucky


Happened at 55k km's, while cruising at 130km/h on dutch highway...... reason unclear, exhaust valve just broke Valve pipes OK, no exessive play.
Just bas luck I guess, valve pipe play was a common problem in the first model year (mine is 2006). You and me are the only ones with a broken valve,that I know off.
Only symptom before the breakdown was bad starting, but had checked valve clearance etc, all OK. On the day of the mishap it behaved perfectlly however..... drove home from Germany Morini Meet (2013), 700+ km's (well, in my case allmost 700+ km's....)
As you had the head off, I would have replaced all valve pipes, as a precaution and not expensive, but that is a bit late advice now.

[vtxbrit]

ouch that cylinder head looks f***** sorry you have been so unlucky.......main thing is you are ok, I’ve only seen one other bike drop a valve (Jawa speedway engine) the valve head dropped off and destroyed the head, cylinder and piston, we think it was an over temperature problem, best of luck sorting out the problem
vtxbrit

[Arjula]

Hi MonstroMorini. Is yours also front cylinder? Quite bad looking. So, it seems that you need new cylinder head. Yes, I think that I was lucky.

I found quite strange when I remove front exhaust pipe. The gasket between cylinder head and exhaust pipe, the hole size was smaller than these!!?? That will affect directly to exhaust gas flow.

Unfortunately I do not have photo of it but when you remove front pipe, check that gasket hole size and compare it to exhaust pipe hole size and cylinder head exhaust hole size. You see the difference.
I think that this is design error and need modification. Exhaust gas will not flow directly on this phase and this will heat this area quite much, I think. I enlarged the gasket to fit more together with cylinder head exhaust hole and with exhaust pipe hole. I think back cylinder exhaust gasket have same problem.

If I compare mine and your photo, it seems that there is quite much black comp. This means that engine does not burn gasoline clear enough. It may run too rich on some rpms or engine cannot burn gasoline, because gasoline is not enough molecular than it should be. Black comp will occur.
It may be possible that this black comp will loosen sometimes and some particles stuck between valve plate and valve ring. Then exhaust valve is not close enough and will be little open. Hot gas will burn valve and it melts.

I think that the main problem is in poor injectors. Injectors are spraying gasoline too fluid. So gasoline is not gaseous state enough when it goes in to cylinder. It just flows to intake valves and firing is not clean enough. That is why silencers holes are so black because it just cannot burn all gasoline.

I have thinking about this and I have crazy idea to find out different injectors what can spray gasoline more smaller particles like more gaseous state before intake valves. This may also need more pressure in injector pipes.

Fuel pump will run all the time when bike is running. On backwards line, inside the tank there is pressure valve what is fixed adjusted to 3Bar. So when pump lifts up pressure to 3bar, this valve will open and keeps always 3bar in the injector line.

When key is turned on, fuel pump is programmed to run about 3 seconds. Pressure will go to 3bar on that time. This pressure should be enough when start motor is running.
I think fuel pump can do more pressure but pressure valve will control the pressure. I have tested using pressure meter. When key is turned on, pressure rises to 3Bar very fast.

So what about to change that pressure valve to higher pressure valve (5bar example), it will make higher pressure to injectors. So then injectors can form smaller molecular, more gaseous state into cylinder, motor can burn better vaporized gasoline more clear and black comp will not occur.
This should also affect to fuel more efficient consumption or even get higher power.
Also motor can be more efficient and comfortable also slow rpms.
If new injectors are used, of course it means new whole ECU mapping in dyno run.
Crazy thought, but may be interesting to test.

This will need higher pressure valve, different injectors what can form smaller molecular gasoline to intake valves, new ECU mapping with dyno run.
But those exhaust gaskets should be fix before do anything.

[MonstroMorini]

No, it was the back cilinder, in my case. It happened june 2013, riding home from the morini meet in germany https://www.flickr.com/photos/monstromo ... 751524875/

But also the intake valve was bent and broke (as the exhaust valve probably hit it) and parts of the valves were sucked into the front cilinder. So i didn't even bother (after informing the prices) with spare parts (had to wait 9 weeks for gaskets btw. but i hear from my german collegues that delivery is quick now) and bought a replacement engine with only 1200 km's on the clock. It was taken in by the dealer at the 1000km inspection as the owner complained about very heavy gear changing.
It was completely taken apart and not complete, so i had to use some parts from my original engine. On a positive note: all parts inside the "old" engine (clutch, gearbox, distribution and all other internals apart from cilinder/head were as new. The distribution chain/gears did not show any wear, although replacement is advised at 40k by Morini. However, I seldom use the top rev range, as it is never necessary to rev it up when keeping ip with my mates

On the exhaust gasket: I am afraid you have the wrong part and have a Avio/Sport/Scrambler/Granpasso gasket, which heads have smaller valves and exhaust pipes.
On the fuel injectors: there are also injectors available that (at the same presure) take care of better "spraying" the fuel and are placed over the intake, but I can't find the source right now..... Ducati is using them now, i believe. However, without a dyno I wouldn't change that, because extensive remapping will be required.
On the black carbon residue: you are right, caused by the racemap. I had been running the lean CORA (std 2010) map for a while and just returned from a dolomite trip with my mates, which sometimes forces one to tank E10 fuel. Days before leaving to the MoMoMeet, I was confronted with bad starting and sometimes stalling when idling (and no time to examine everything thoroughly), i changed it to the racemap, which ofcourse is much richer.
Found a problem with my fuel-pump wiring (one of the leads connecting the fuel pump under the tank had gone bad) so thought I solved it.....

On the day it happened I left Lindenfels, first 100km quickly over small roads, then onto the autobahn, as it was pouring rain. So moderate speed, then about 300km's dry and speeds between 160-180 km/h. Then dutch border and back to low speed, 130 km/h (expensive tickets overhere) and after about 50 kms the engine broke down.
During the day no problems, oil OK, water temperature never over 78 degrees, so no obvious reason..... also some friends have checked the damage, overall conclusion: bad luck

[corsaro chris]

I had a valve go on my 2006 Corsaro, fixed under warranty at a service with NLM at 12,000 miles and 2 plus years after purchase... No noise, just poor starting.

Borrowed a 9.5 for a month to go to the NW200 while it was fixed!

CC