CMB .67 twin plug parts

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Joined
Nov 29, 2019
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774
I just picked one up and want to rebuild it. I want to replace all the bearings and gaskets. Possibly a piston and sleeve as it doesn’t seem to have a lot of compression. Also who can modify this motor for me?
Thanks
 
My suggestion is to sell it and buy a newest version 67. It makes zero sense to mod an engine that is hard to get parts for. A stock modern 67 makes great power right from the box. And all parts are available.
If someone modded it themself that’s different. Good luck.
 
My suggestion is to sell it and buy a newest version 67. It makes zero sense to mod an engine that is hard to get parts for. A stock modern 67 makes great power right from the box. And all parts are available.
If someone modded it themself that’s different. Good luck.
Thanks Danny, I have new engines but I have this one sitting here and at the very least want to replace the bearings and get it running.
 
I just picked one up and want to rebuild it. I want to replace all the bearings and gaskets. Possibly a piston and sleeve as it doesn’t seem to have a lot of compression. Also who can modify this motor for me?
Thanks
The gaskets will be the hard part, but you can use Yamabond #4 as a substitute. Also, by eliminating the rotor backplate gasket and sealing with Yamabond, you eliminate the excessive rotor clearance CMB manufactured them with. Also check wrist pin area for proper fit.

The bearings aren't that difficult to find...you'll need to examine them, under magnification, and find an ID.
And then hit the bearing houses, like Boca.

Danny's right....however, side by side, the full circle crank setup in the twin plug engine makes more torque than a cantilevered crank in a 'modern' 67, stock or modded. All about the inertia, but a lot of work is needed on the old Evolution engine.
 
The gaskets will be the hard part, but you can use Yamabond #4 as a substitute. Also, by eliminating the rotor backplate gasket and sealing with Yamabond, you eliminate the excessive rotor clearance CMB manufactured them with. Also check wrist pin area for proper fit.

The bearings aren't that difficult to find...you'll need to examine them, under magnification, and find an ID.
And then hit the bearing houses, like Boca.

Danny's right....however, side by side, the full circle crank setup in the twin plug engine makes more torque than a cantilevered crank in a 'modern' 67, stock or modded. All about the inertia, but a lot of work is needed on the old Evolution engine.
Thank you Tim, does CMB still make a piston and liner or is there one that’ll fit? I pulled the head button and found a very small nick in the piston on the exhaust port side and what appears to be some going right above the exhaust port as well.
 
Thank you Tim, does CMB still make a piston and liner or is there one that’ll fit? I pulled the head button and found a very small nick in the piston on the exhaust port side and what appears to be some going right above the exhaust port as well.
I have a brand new, never been installed piston and sleeve I may want to sell. I also have new bearings in package, but would like to see if I can source them before selling.

For mods, talk to Chris Wood, as he campaigned a 67 EVOlution quite successfully. His dad, Steve, knew all the tricks with that engine, as does Andy Brown, I'm sure.

I will tell you that it likes about 190° max on the exhaust and about 28° of blow down.

You can easily adapt the 45 RS EVO rotor backplate to it so you can run the Speedmaster large bore 45 carb on it....that integral carb as is on the 67 isn't nearly enough.
Tidewater Engineering made a square bore barrel that added some CFM's, but they're hard to find and require machining of the backplate.
Get a hold of Bradley Maglinger, he may have some- I got one from him.
 
I have new crank assemblies with rods installed from factory, extra rods, cases, flywheels (but no cones) front plates, cooling jackets & lots of rear cage needle bearings.
Also have new 65 EVO P/Sleeves that might work in 67's...?
 
Alan I’ll definitely need bearings. Do you have a different front plate so I can run a different carb?
Backplate....check with Joe Warren...make a WTB ad up over on the 3 Facebook Groups, Stephen.
Make one here, too.
Stu has new ones for around $53 (don't quote me!), Tony has them in Australia, and Dave in UK probably has them, too.
 
Tim here are the pictures of the piston and liner. I asked Stu about a new front plate and he said he didn’t have any.
 

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Tim here are the pictures of the piston and liner. I asked Stu about a new front plate and he said he didn’t have any.
Yeah, I don't know....had asked him to send an updated price list, but nothing. Rumors abound on FB that supposedly he's only selling to who he wants to...I'm staying out of that crap, though.

Your P&L doesn't look too bad...I've run worse. If you've got money to blow, well.....

Then again, hard to tell from photos, light reflection and all.

I believe the part you're looking for is technically the backplate....I posted the CMB part# over on thread we started 'WTB'....if Stu doesn't have one, give Tony Grinter an email....he's prompt, US dollar is stout in AUS, and delivery takes about a week-

[email protected]

About all I can tell you at this point.
 
Yeah, I don't know....had asked him to send an updated price list, but nothing. Rumors abound on FB that supposedly he's only selling to who he wants to...I'm staying out of that crap, though.

Your P&L doesn't look too bad...I've run worse. If you've got money to blow, well.....

Then again, hard to tell from photos, light reflection and all.

I believe the part you're looking for is technically the backplate....I posted the CMB part# over on thread we started 'WTB'....if Stu doesn't have one, give Tony Grinter an email....he's prompt, US dollar is stout in AUS, and delivery takes about a week-

[email protected]

About all I can tell you at this point.
Thank you buddy!
 
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