New 21 CMB Beta

[shoboat]

Tim,

Try a OD-289 plug. I have another propeller for you to test on your set up.

Thanks,

Mark Sholund

 

[timothy johnson]

Thanks Mark sent you a PM Tim

 

[David Murany]

Ran my JAE Beta several times over the weekend . I ran the engine at .009, 8'' CMB nitro pipe, 55% , OD Blue plugs and a Shouland H-7. The engine is still getting broke in but is running much better than my VAC motor. I ran the engine at .112 for fuel flow and water at 120. I did burn a few plugs with a coil pulled out so if any one is having better performance with another plug please post your info. Thanks to everyone for posting their comments Tm

All we run are the blues as well. The last time I ran my Beta I was at 90 on our meter. It seems that as the motor loosens up it is taking a lot more fuel which is a good thing. This may be why you took plugs. Try running richer. I'm also at 7 7/8 with the pipe.

 

[timothy johnson]

Thanks David, I will reset my needle to 90 and see how it goes. thanks Tim

 

[timothy johnson]

Ran the Beta today at 98 on the flow with a H-7 , no blown plugs and the motors doing well. Still a little tight on top so lots of room for improvement!

 

[David Bryant]

Interesting (to me) that this new CMB .21 Beta engine performs significantly better than the previously released CMB .21 VAC engine. Why is this? Bore & stroke are equal. Is the main difference in exhaust and intake timing?

 

[JoachimRuess]

David,

the main difference is not the timing but the inner case volume.

If you take a .21 VAC and take the Beta-case you get a much better engine.

Joachim

 

[David Bryant]

I see, thanks

 

[eekern]

I/m guessing the case volume on the Beta larger than that of the VAC???

 

[JoachimRuess]

No, the case volume of the Beta is smaller so that the gas speed is increasing.

 

[David Bryant]

so is the liner port configuration completely different from the 45VAC as well? Quantity of ports, etc.,...?

 

[Stuart Barr]

Dave,

The new 45VAC piston/liner configuration in now like the BETA (8 ports)

Stu

 

[David Bryant]

thanks Stu, great to know

 

[timothy johnson]

Has anyone tried the Andy Brown STL Billet pipe .Thanks Tim

 

[timothy johnson]

Has anyone tried Turbo plugs on the Beta yet?

 

[Stuart Barr]

Just received the new BETA 21's. Head clearance problem has been resolved and no head cutting is necessary. Stock clearance is at .009" with stock head shim at .008". With a head shim kit, easy to set at .006". On sale now (until 12-15) for $405.00

Stu

 

[timothy johnson]

Stu did a great job in solving this head cl. issue by letting CMB know the problem his customers were having and they were able to fix it so we can move on with using and winning with this new motor. Thanks again Stu. Tim