Mittwoch, 16. Mai 2018

Saito radial engine repair

As almost every RC fan I'm fascinated by model engines. Most of them are however quite expensive to buy new or even used.

By the end of 2017 I got hold of a very cheap but broken Saito radial engine. With the experience that I have built over the years of flying gas and nitro engines I was very convinced that I would be able to get also this engine back up and running. I only did a few rough calculations if for the given price it was even possible to repair without paying more than I would have for a good running used one...
Immediately after the parcel arrived I wrote a list with all the broken and missing parts. The engine has already been disassembled by the previous owner, but he did a wonderful job packaging and marking all the parts. That made my job a lot easier...





The damage was quite substantial as the previous owner had an unplanned 'landing' at the airfield. With broken Cylinder, Rocker arm brackets and ripped screws there was a lot to be done. Luckily I was able to drill some of the broken screws out and save some more parts that I would have otherwise had to buy new. Also the crankshaft and the matching bearings where in good condition. Here just a few impressions. There where a lot more parts damaged but I think they illustrate it the best...




The whole cleaning and inspection took 2 days in total and afterwards I placed an order for the missing parts. Unfortunately the shop I ordered them from had to order them from Japan (Saito is a Japan company) so the delivery could have taken over 3 Month. Again having luck the parcel arrived by the middle of February. I also could have ordered the parts at a local German hobby shop but they would have cost more than twice as much. 




The day the parts arrived I started sorting and assembling of the parts. Unfortunately one of the cylinders had a large leak at the exhaust valve. I decided to try to grind it in using some abrasive cleaning solvent. However it did not work at all. Maybe if I would have ground it a lot longer than I already did. After that I bought a proper valve grinding kit for a few Euros. This grinding paste was way more on the coarse side and made fast work of the leak. Another night of valve grinding and screwing parts together later I had 2 cylinders in place with decent compression. The third cylinder got assembled in the following morning. The engine got to me with a Keleo customs exhaust. It was in really bad shape too. Having no exhaust but a ready to run engine I took a flip without a muffler.
It fired up at the third try and ran pretty smooth afterwards. 






With that result I was really happy having invested in the broken parts only the muffler being an open issue. Two weeks later I tried to get the muffler back into shape. Propane torch, huge clamps and a vise later I finally got it, so that it would fit the engine again. It's certainly not a thing of beauty anymore but the sound will not be affected by that. And as it will be screwed under a hood it won't be seen too.




Hopefully the repairs will last a long time and I will find a suitable airframe in the future.




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