I just bought an MVVS .49 and have a concern. In the attached picture (sorry for its poor quality), you will see that the relief for the back port is triangular and is quite rough. I did extract a metal casting flash shard that almost filled the entire triangle. The not so local shop I bought this from claims that their .45 is similar. (He has been reliable in the past). I haven't run the engine yet soo...

Should I send it back or is this normal for MVVS engines?

Ken Revak

I don't recall seeing or checking for that matter on my two 49's. I would say check the entire area and remove any thin material etc and run her. Make sure of course the O-ring on the back plate is seating on material all the way around!

It would be a lot less frustration to just fix the thing and go about your business.

Enjoy,

Jim

Is that thing a three port schnuerle engine, or what ? That "port" doesn't
look quite right to me.

FBD.

Ken,


This is very atypical for current MVVS engines.

Since I open and check each and every engine that I sell, before giving/sending it to the customer, I can tell you that I have not encountered any such slag on the inside of any engine.

Any harmful foreign matter (aluminium particles?) is equally rare.
Sometimes there is some congealed oil, or fibrous matter, from the cloth/paper used to wipe the engine after machining.

As Jim wrote, it should be less of a bother to disassemble and carefully clean away those imperfections, just be careful not to scratch what should remain smooth (for sealing), or you may void the warranty.
It should take you about half an hour, including disassembly/reassembly.

The relief at at the rear of the crank-case becomes a "port" if the cylinder head is rotated to configure the engine for rear exhaust. If you purchased the engine through Triad Aviation Ken, I will swap you for another one if you would like, no problem. I must admit that we don't open every single engine up and inspect it like Dar does, but the ones we have inspected have been perfect. The engines are hand assembled and such a large piece of metal should not have been overlooked. On the other hand if you choose to clean it up yourself and get on with flying the engine, please accept my appologies on behalf of the factory. If you can get a better picture of the engine and the peice of swarf you removed I will pass it back to the factory and see that someone gets smacked with a trout.

I found a few small pieces of glass/sand from the blasting (finish appearance ) process embedded between the fins of my .49...I picked 'em out and dis-assembled the rest of the engine (except for taking the crank out ) and cleaned it as I always do.

IMO, if there is a little bit of flashing at the very bottom of that particular port, you should be able to remove it easily, but I think that when you put the backplate back in, it will "mask" that area anyway, so that little bit of flashing is not going to make any difference as far as flow is concerned, whether you use side or rear exhaust...