Byra competition 2.5cc from 1955
Another spanish Ikon from Spain..the BYRA 2.5 !! It was a popular engine in its days.
The regular 2,5 cc had a plain head....the "black head Competition" had a slightly bigger ventury to boost performance. And for sure a not bad runer with useful rpm.
Its another engine I rebuild for my friend Adrian Duncan ..
How ever,it had some issues...
Make a new piston,as the heat up trick dont work with the steel piston of the Byra.
Bearings and seals were toast..as always..
The threads on the engines are mostly far to loose ...so also this engine...I wrap careful a thin layer of strong alu foil on the liner thread,to get a nice tight fit in the carter. Also is the Byra known to run pretty hot..and as the head was also pretty loose,I do the same to the head thread,so it wil transmit the heat wel to the cooling head and ribs....
The shaft is only 7 mm thick,so they are known to break just behind the disc web...
I made some time ago a replacement for my dear friend Jesus..and made a thicker version,with a 8mm section at the rear bal race..what is far stronger..
The genuine Byra 2,5 miss a bit high RPM smoothnes ,so I ad a smal thin alu washer under the liner, to have the transfer ports a bit longer open.
... the miss fireing on high rpm in the "Aero modeler test" was cause because of that..lack ...of transfer opening..
.As wel,I have smooth al sharp edges on the Piston skirt, transfer edges, and the edges of the new Tufnol rotor..Al parts are made wel,so after a good run in time,it should perform pretty well...After the rebuild,its still tight at TDC,so it need to settle down.
But when this is done,I am sure it wil go above the 0.195 of the test rapport in its days..I would say something in the range of 0.25+
The full review you can find here..
http://sceptreflight.com/Model%20Engi...
l am sure,my good friend Adrian wil give it futher run in time and a good test,so we can see the real potential of this classic Spanish engine..
Have fun,watching the video..and enjoy your old vintage engine!! Happy flicking..see you soon..dont go to far!