"No Word" From New CMB 21 Beta

[ALLAN YUEN]

I just watch on Where did anyone run with new CMB21 Beta ??

 

[Stuart Barr]

Jim Wilson in California just ran his this past weekend. Jim's pit guy, Rudy, said "CMB finally has a great 21 motor". Great torque, great rpm.

Stu

 

[D-7]

Hi Allan,

in german modelmagazine is test from beta, go via link (under the rescue boat is online link)

http://www.bruckmann.de/zeitschrift-schiffsmodell_19.html?heft=1150

 

[Tony Ball]

Hi Frank

Report has disappeared

 

[shoboat]

Boaters,

One of the CMB Team Drivers Alex tells me it is running very well lately.

It looks like one nice motor. Alex your propellers are on the way tomorrow.

Thanks,

Mark Sholund

 

[ALLAN YUEN]

I just hear that all whole old Beta eingines sent to return to CMB Factory then big change improve??

I don't know why !

 

[Bradley Maglinger]

I just hear that all whole old Beta eingines sent to return to CMB Factory then big change improve??

I don't know why !

Never heard that, I still have my two betas going strong!

 

[David Ashcroft]

The. 21beta is off the list on the Aussie distributor site. Must be waiting for the black head model to replace.

 

[JUSTINROGERS]

So here's my experience with the situation I ordered two CMB beta's and a CMB RS outboard powerhead received all 3 the betas were supposed to be the new M1 kit however the cranks are not the M1 cranks.so with that aside I put the beta in my JAE ran five tanks through it and it ate a rod bushing. Upon taking it apart to find out what was wrong with it when I found the con rod bushing found Machining grooves in the crank pin enough to where you can run a razor across it and feel it clicking and you can hear it clicking. I contacted my supplier told him the situation he contacted CMB for replacement parts. The new parts came. new Conrod, new crank, new bearings, the replacement crank is the New Balance crank which still has the Machining grooves in the crank pin and also the inserts for the balancing on the crank have gaps between the crank and the insert. Not sure why such bad quality parts are leaving such a great company would really like to know what's going on. I will post pics later today.

With all the bad said. With the new conrod in and me polishing the crank pin the engine runs great. Its now pushing my JAE 67 mph on gps. Heres a video of one my heats from the last race. I jumped the start and came from a lap down to almost passing the leader in the last turn on the last lap. Had some tank problems and ran out of fuel. But the engines really running good!!!

https://youtu.be/nNe-hB71QVo

Thanks Justin

 

[JUSTINROGERS]

The original crank. Its a little hard to see the grooves in the crank pin

 

[JUSTINROGERS]

The crank out of the 2nd backup engine. Has the same grooves.

 

[JUSTINROGERS]

And the new replacement crank. Has the same grooves as the non M1 crank. A defect just above the crank pin (the black grove). And i may be wrong but i dont like the void in between the crank and the balance inserts especially on something that turns 30,000 plus rpm's. But that's just my opinion.

 

[David Ashcroft]

Yes them balance inserts look a bit suspect.

 

[JUSTINROGERS]

So im not crazy lol.

 

[Ken Retallick]

The gaps may only be the chamfered ends on the inserts.

 

[brad nichols]

Could they be threaded in or you think they would be center punched??

Brad

 

[brad nichols]

Are they threaded in or you would think that they would be center punched??

Brad

 

[Chris Wood]

Most likely the inserts are press fit

Man that is lousy machining. Cmb always has had some quality issues I am shocked they don't take more care in addressing them.

Sent from my iPhone using Tapatalk

 

[Charles Perdue]

I do not have a dog in this fight but as I have balanced cranks this way, the pin material is relatively soft compared to the crank material. With a tight press fit, if you do not have a good chamfer it will shave material off the pin. When this happens the pin will come out, not good.

Mr. Jim Allen can give you the specs better than I can......

Charles

 

[Terry Keeley]

The gaps may only be the chamfered ends on the inserts.

That's what it looks like to me. They didn't make the slugs long enough to completely clean up when they finish ground the crank.

Prolly fine...