Rebuilt V11 Sport Won't Start

[Chuck]

 "They appear to lightly be touching the piston, which obviously isn't good, but since they don't seem to be hitting that hard, I'm hopeful that they will be in good condition (I can still turn it over by hand, so they valves aren't stopping the pistons). "

 

when I was building the Aero engine, Ilooked up a lot of this kind of stuff. Of course.. I've promptly forgotten, but .030" clearance rings a bell. At any rate, look it up to be sure.

[thelonewonderer]

I haven't had time to pull the heads and check the valves, but I did tinker with it a bit today. 

 

I put the borescope in the cylinders and turned over the engine to see which valve(s) were making contact with the pistons. I turned the crank all the way around multiple times and not once did any valve touch the pistons. I also examined the heads of the pistons and there were no hit marks on either of them. 

 

The timing marks on the gears are lined up when the LH is at TDC, which should mean that the timing isn't off by a tooth or two.

 

I thought I had come up with ideas on how to correct the timing, but when looking at everything those ideas go out the window. 

 

I've been watching and re-watching the video on "This Old Tractor" (here is the link if anyone is interested: http://www.thisoldtractor.com/moto_guzzi_technical_training_videos_eng.html)and I have installed the timing just like they do in the clip.

 

Just to think out loud so someone might be able to see where I have gone wrong:

 

The missing tooth on the phonic wheel has to be opposite the timing sensor. This places the camshaft pin where it should be for the cam timing gear to line up (roughly 10 o'clock). When setting the timing marks on the bench, the hole for the pin on the cam gear is in the correct place.

 

One then has to turn the crankshaft so that the key lines up with its position on the crank gear.

 

Once everything is lined up, one can install the timing gears and chain. If the timing marks still line up, everything should be fine.

 

The key on the crank should guarantee that the crank is in the correct position and the pin in the cam should guarantee that the cam is in the correct position. If this is true, then the pistons and valves should be in proper sync.

 

Where have I gone wrong?   

[Lucky Phil]

 "They appear to lightly be touching the piston, which obviously isn't good, but since they don't seem to be hitting that hard, I'm hopeful that they will be in good condition (I can still turn it over by hand, so they valves aren't stopping the pistons). "

 

when I was building the Aero engine, Ilooked up a lot of this kind of stuff. Of course.. I've promptly forgotten, but .030" clearance rings a bell. At any rate, look it up to be sure.

Valve to piston should be around 1.5mm on the inlet and 2mm on the exhaust.

 

Ciao

[thelonewonderer]

 

"They appear to lightly be touching the piston, which obviously isn't good, but since they don't seem to be hitting that hard, I'm hopeful that they will be in good condition (I can still turn it over by hand, so they valves aren't stopping the pistons). "

 

when I was building the Aero engine, Ilooked up a lot of this kind of stuff. Of course.. I've promptly forgotten, but .030" clearance rings a bell. At any rate, look it up to be sure.

Valve to piston should be around 1.5mm on the inlet and 2mm on the exhaust.

 

Ciao

Thank you! I'm going to clay the pistons when I pull the heads.

 

Sent from my SAMSUNG-SM-G930A using Tapatalk

[Lucky Phil]

 

 

"They appear to lightly be touching the piston, which obviously isn't good, but since they don't seem to be hitting that hard, I'm hopeful that they will be in good condition (I can still turn it over by hand, so they valves aren't stopping the pistons). "

 

when I was building the Aero engine, Ilooked up a lot of this kind of stuff. Of course.. I've promptly forgotten, but .030" clearance rings a bell. At any rate, look it up to be sure.

Valve to piston should be around 1.5mm on the inlet and 2mm on the exhaust.

 

Ciao

Thank you! I'm going to clay the pistons when I pull the heads.

 

Sent from my SAMSUNG-SM-G930A using Tapatalk

 

Yep, or you can lever the valve open at max lift on the overlap with a dial gauge attached and see what the claerance is.

 

Ciao

[coreytrevor]

That works, and it's a lot less work.

 

I would also check clearance after TDC, and maybe before. When my intake valves were tapping the piston, it wasn't at TDC. The valves were opening and catching up to the piston after it was already traveling down the bore.

 

Edit:  Lucky Phil, when I read what you wrote, I took it to mean to lever the valve open during overlap, at/near TDC. Reading it again, I think you probably meant to do it at max valve lift.

[Lucky Phil]

That works, and it's a lot less work.

 

I would also check clearance after TDC, and maybe before. When my intake valves were tapping the piston, it wasn't at TDC. The valves were opening and catching up to the piston after it was already traveling down the bore.

 

Edit:  Lucky Phil, when I read what you wrote, I took it to mean to lever the valve open during overlap, at/near TDC. Reading it again, I think you probably meant to do it at max valve lift.

Sorry, max valve lift on the overlap just before TDC on the exhaust stroke for the exhaust valve and just after TDC on the inlet stroke on the inlet valve. During the overlap period.You can sometimes do it with a lever or a light weight valve spring or a light spring with a removeable retaining clip ( valve drop check) or with clay or soder with the head off.

 

Ciao  

[68C]

You could try temporarily replacing the valve springs with very light springs, then slowly turn the engine over little by little checking the valve can still be pushed down and so are not contacting the pistons.

No need to remove the cylinder head. Use the old trick of filling the cylinder with string (leaving a tail out of the plug hole) then winding the piston up so the string compresses against the valve head. Now lever the valve spring cap down and remove the collets, cap and spring. Fit the light spring, cap collets etc. Remove the string and check as described above. Anyone who has done much work on aircraft piston engines will know this one.

 

Edit:  Should of added remove rocker arms for access to collets etc,  and make sure you are on compression stroke. 

[luhbo]

I know this procedure done with compressed air. It's quite common when you want to change worn valve shaft sealings.

[Chuck]

Carb springs work really well.

[guzzi323]

No need to remove the cylinder head. Use the old trick of filling the cylinder with string (leaving a tail out of the plug hole) then winding the piston up so the string compresses against the valve head. Now lever the valve spring cap down and remove the collets, cap and spring. Fit the light spring, cap collets etc. Remove the string and check as described above. Anyone who has done much work on aircraft piston engines will know this one.

Oh, I like this one. I've never heard of that trick before. Thanks!

[coreytrevor]

I know this procedure done with compressed air. It's quite common when you want to change worn valve shaft sealings.

 

I've done this a number of times, really easy. Use an adapter from a compression tester connected to an air hose.

[gstallons]

You could try temporarily replacing the valve springs with very light springs, then slowly turn the engine over little by little checking the valve can still be pushed down and so are not contacting the pistons.

 

No need to remove the cylinder head. Use the old trick of filling the cylinder with string (leaving a tail out of the plug hole) then winding the piston up so the string compresses against the valve head. Now lever the valve spring cap down and remove the collets, cap and spring. Fit the light spring, cap collets etc. Remove the string and check as described above. Anyone who has done much work on aircraft piston engines will know this one.

 

Edit:  Should of added remove rocker arms for access to collets etc,  and make sure you are on compression stroke. 

You should describe what type of & diameter string you are using .

[Chuck]

Rope, hanging the laundry variety, 1/4 inch or so diameter..

[68C]

I prefer 6.4mm, too scared to cut a length off her washing line.