CMB EVO 90 breakdown

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John Seybold

Well-Known Member
Supporting Member
Joined
May 22, 2010
Messages
766
Hi,

When breakdown down an EVO style motor, what are some of the do's and don'ts. I figure it would be best to ask for some insight prior to starting.

Thanks for any suggestions and tips,

John
 
That is correct but prior to trying to pull it you will need to get rid of the rest pin clip then insert screw into the threads in the wrist pin pull out through the exhaust port reinserting that wrist pin clip through the exhaust Port is another drawback
 
First time around, you need a lot of patience. Once piston and liner are removed, remove back plate and disk. Then remove flywheel and front housing. Put crank rod assy at top dead center and then it can be removed from case.

Stu
 
A piece of brass tubing with a drill the right size in it will make the insertion of the C clip much more comfortable.

find a brass tube that the pin will fit in lose. then cut a small piece of it just long enough so when you find the drill bit that slides in it. It will just stick out the end of the tube.

Now put the clip in the tube and press it up on the pin hole. then pusher home with the drill bit.

Get some extra C clips as thy don't always come out nice.
 
I stumbled across this instructional video a while back by accident. It features Roman Agafonov, of MiniCraft RC Boats (Siberia?), performing bearing replacement procedure on a CMB .91RS marine engine. Roman is very thorough, he provides some specific techniques in regards to disassembly of these unique engine designs:

 
Another inter-related CMB question, in regards to the CMB .80HR marine engine:

"What is the proper size allen (socket) wrench for disassemby of rear-plate and head assy"?

I tried using a 2.5mm and a 3.0mm, either does'nt seem to fit/function properly? Are these socket head bolts metric? Or english? Could they be 2.75mm?
 
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67 /80's use 6-32 bolts. for some reason they come through with 2 different wrench sizes,some are current standard and sometimes they come with the old standard size(which should be obsolete),from the 30's,i think. Chinese bolts,go figure
 
67 /80's use 6-32 bolts. for some reason they come through with 2 different wrench sizes,some are current standard and sometimes they come with the old standard size(which should be obsolete),from the 30's,i think. Chinese bolts,go figure
yeah, weird. I have 2 brand-new CMB .80HR engines (bar-stock rear plate). Really perplexes me that bolts would be standard sizes. I was concerned because I did'nt just want to guess and "force" whichever socket wrench that seemed to fit.
 
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