cmb 67 purple questions

[moontz]

I picked up this engine a couple years ago used. Decided to put it in a seadcuer 67 this season just to see what it did. Keeps ruining plugs after 2 or 3 laps. I dont think its too lean - 3 turns out.

Anyway, Im trying to take apart to check bearings and this thing is giving me a hard time. First time I have disassembled a cmb of any kind. First, I just realized the carb is welded to the backplate. Never seen that before. In any case thats fine, but how do I get to the bearing on this thing? I got flywheel and collett off and screws on front plate are out. But try to take it off, and there is something holding it on. I dont want to force, but wondering the correct procedure here. The pic shows what I got

http://www.intlwaters.com/uploads/12384818..._612_506577.jpg

sorry for the bad quality. camera phone. But it slides out to this point then hits something and stops. How to get to the bearings? Also, is there supposed to be a gasket here (there is not)?

Thanks

Brian

 

[Stuart Barr]

I picked up this engine a couple years ago used. Decided to put it in a seadcuer 67 this season just to see what it did. Keeps ruining plugs after 2 or 3 laps. I dont think its too lean - 3 turns out.
Anyway, Im trying to take apart to check bearings and this thing is giving me a hard time. First time I have disassembled a cmb of any kind. First, I just realized the carb is welded to the backplate. Never seen that before. In any case thats fine, but how do I get to the bearing on this thing? I got flywheel and collett off and screws on front plate are out. But try to take it off, and there is something holding it on. I dont want to force, but wondering the correct procedure here. The pic shows what I got

http://www.intlwaters.com/uploads/12384818..._612_506577.jpg

sorry for the bad quality. camera phone. But it slides out to this point then hits something and stops. How to get to the bearings? Also, is there supposed to be a gasket here (there is not)?

Thanks

Brian

Brian,

Use a flywheel puller to remove front plate. It should slide off unless crank is galded. Front plate has an oring seal. You will need to go thru exhaust port to remove wrist pin clip and wrist pin. Remove piston and liner. With crank at TDC, crank can be removed from case. If you have not disassembled this style of motor before, it will make you swear. If you do not want to tackle this, contact Steve Wood, Rod Geraghty or Steve Cooper and they can help you.

Stu

 

[moontz]

Brian,Use a flywheel puller to remove front plate. It should slide off unless crank is galded. Front plate has an oring seal. You will need to go thru exhaust port to remove wrist pin clip and wrist pin. Remove piston and liner. With crank at TDC, crank can be removed from case. If you have not disassembled this style of motor before, it will make you swear. If you do not want to tackle this, contact Steve Wood, Rod Geraghty or Steve Cooper and they can help you.

Stu

Thanks Stu. What are your (or anyone elses) thoughts on these motors. Not sure exactly what it is - other than a cmb with a purple head. Seems to run ok before it looses the plug. Worth investing the time in or move on?

Just trying to resurrect an old seadcuer 67/80 and have a bunch of old motors sitting around - older Picco 67 silver head, ops 67, ops 80, os 81, and this older purple cmb 67... Reason I chose the cmb was bolt pattern matched the engine mount. Would the ops or picco give me better results?

 

[jeff baham]

i have two gold head engine like that, they are great running motor, but parts are getting harder to fine.

 

[moontz]

i have two gold head engine like that, they are great running motor, but parts are getting harder to fine.

ya, the motor seemed strong. only had 2 plugs and burnt them both before i could put a gps on it