Cmb80hr

[David Ashcroft]

Anyone have good info on the new cmb 80 hr .my first 80 size engine in a mono and like to know what CC volume works best on the head,with .12 thou clearance with 50-60%fuel,,will have stock timing to begin ,I will be using the cmb 67/80 large volume pipe,

 

[brad nichols]

Well to start you should talk to Stu Barr himself as he sells them and is very good and a wealth of information. I am sure that others here on IW will share there knowledge too.

Brad

 

[David Ashcroft]

no problem Brad thanks ,I was going to get a button or two made up ,with different cc and angles ,I will just experiment...

 

[David Ashcroft]

So does anyone with the new bluehead 80hr got some timing measurements I got 188exhaust and the transfer intake duration of 139degrees with 24.5 blowdown anyone similar measure.??

 

[timothy johnson]

David some #s that Steve Wood did for me EX 188.3 x TRANS 128.3 x BD 30 runs quite well.

 

[David Ashcroft]

Thanks Tim I will measure again my transfer seems a bit high.

 

[timothy johnson]

David are you using Marty's program? I just did a couple of CMB 67s with Steve's liner shims. One is at EX 190 x Int 130 for a BD of 29.9 and the other is EX 188 x Int 131 with a BD 28.3. I'm thinking they should both run well.

 

[David Ashcroft]

Yes Marty's program... Them .67 numbers look good.. I will consider shimming the liner .

 

[David Ashcroft]

Ok I re-measured and I get stock measurement 188exh and 130transfer.

 

[David Ashcroft]

So I got stock rotor case ID 0.706" and rotor. 0708"bit tight

 

[David Ashcroft]

Stock volume. 72 cc

 

[steve wood]

early 80's had too small volume,like .57 cc. i made heads .68 to .72. if interested i have a bag of 80 buttons,maybe 10 to 15

 

[David Ashcroft]

I chasing .68cc with 2degree and. 248 " band

 

[Duke Mordja]

early 80's had too small volume,like .57 cc. i made heads .68 to .72. if interested i have a bag of 80 buttons,maybe 10 to 15

Steve,

I am interested in head buttons for the CMB HR 80's

What material are the head buttons?

Duke

 

[steve wood]

Aluminum