franchi

Hello All:

While running a MVVS 2 cc Diesel I noticed that the crankshaft could not be turned more than about 80 degrees after bdc. I also noticed that the cylinder had rotated to the left with only a small opening ,5mm, showing on the right side of the exhaust port. Now to turn the cylinder to the correct position.

Turning the cylinder sounds like as easy task but it is fraught with great difficulty:

With the piston unable to rise to tdc, there is nothing to push against to remove the cylinder.

There is very little to grab with pliers, just kidding, on the top of the cylinder to turn or pull.

Is that a snap ring near the top of of the cylinder. Removing this may facilitate removal of the cylinder but the ring cannot be removed until the cylinder is raised a small amount.

On the first tank of fuel, this engine screamed on an 8-3 prop!

Any suggestions as to how I may remedy my problems or information as to how this happened? How can a cylinder rotate in an assembled engine is a mystery to me!

After heating the case What tool would be suggested to turn the cylinder. All that I can think of is a Stillson, pipe, wrench or a pair of pliers. UGH! Perhaps a small hose clamp attached to protect the cylinder.

Bloody Hell, it is only a small two cycle engine with three moving parts!

Tia,

Franchi

franchi

The engine is repaired but one lingering problem remains, sticking contra piston. The contra piston will not move the final small amount to contact the compression adjusting screw. This permits the screw to turn the entire way out of the head.

How does one fit the contra at the very top of the cylinder to enable it to be free enough to move but still hold compression? I cannot force the contra to move the slightest bit so lapping may be a bit of a challenge. What about chuckling the sleeve in a lathe and polishing the final bit until the contra will move? I have bee told that the pressure while running will blow the contra against the screw but not in this case!

Suggestion/comments

Tia

Franchi

franchi

Hello All:

Final notes re. MVVS Diesel.

I sanded the cylinder until the the contra piston would move enough to make adjustments. Of course, the the contra prevents the adjusting screw from moving. If not, I will fabricate a locking device.

I do not believe that the cylinder turned while the engine was running. It is more likely that it was not installed correctly when I purchased the engine.

Thanks for listening.

Franchi