Thread: Discussion Model Diesel Engines
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Old Oct 08, 2012, 02:37 PM
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The windy west coast of Sweden
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The Kolibri has landed...

As I've got a soft spot for small displacement diesels, I took a chance on this OTM Kolibri from 1976...
A cute little engine indeed, but as I'm aware of a few "dark spots", I started with a dismantle, to see what I really purchased....

First, the compression T-bar ends were rough in an unpleasant way...sharp really, like they've been trimmed by my local electrician....
This was an easy fix, with some wet emery paper. The T-bar feels much nicer now...

The engine was moderately oiled from factory, with a slightly rough feel. I guess a VERY careful run-in is essential.
Cyl/piston fit is good, with a noticeable taper.
The contra piston (steel, luckily...) fit is slightly on the tight side "upstairs", but probably functioning.
(is there a safe & simple fix for this...?...advices are gratefully received...)

All threaded fits are good.

As I've heard of a "short gudgeon pin" issue with this engine, I was a bit worried, but it doesn't seem to be the case with this example.
The pin ends, roughly, 0.12 and 0.20 mm from the cylinder wall, so there's no chance it could slip out of the hole one side, like I've heard of. I just hope that the pin is a tight enough press fit, to prevent it from moving around and chewing the cylinder wall....
I did a slight "cold" press test, and so far it seems fairly tight...

I didn't manage (dared) to press the propdriver off, even when applying heat, so I left the crankshaft in place.

One point of critisism is the turning of the crankcase, which is NOT quite centred (see pics) in any direction....we'll see how this might affect things....
Hopefully the "two holes" are 90 to each other. (,,,am I an optimist?...)

An intresting note, is this engine's similarity to the Webra Piccolo...trying to be a gentleman, I say it is "inspired by" the same....
(I tried the Piccolo cylinder liner on the Kolibri....same thread...!)

So far, my feelings are mixed.....basically I love this little engine for its "cuteness" and small size...on the other hand I am slightly dissapointed with the manufacturing standards at a few points....
I was somehow prepared for this though....

We may, however, have runner here...future will tell....

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Last edited by Gluehand; Oct 08, 2012 at 04:00 PM.
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