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Discussion Starter · #1 ·
Hi Folks,

Some input would be appreciated.

I've completely disassembled (2) CB350 engines, one from a 72 the other from a 70 in hopes of having enough serviceable parts to make one good engine.

I've started the inspection and measurement process and will be looking for professional help with a re-bore/piston selection and installation of new valves, guides etc in the head. I'm not looking for a performance boost, reliability is my biggest concern.

It seems like Bore-Tech is the "go to" place for cylinder boring and piston matching but I would like to confirm this and I'd be happy to look at recommended alternatives.

As far as the head work, I do see a couple services listed on E-bay...HAS ANYONE USED THESE GUYS??

Finally, it looks like the cam box side covers (point and speedo sides) are toast...one set is very oval-ed out and the other set has visible scratches where the cam ends ride. All I've been able to find are pricy NOS items. IS THERE A BETTER SOURCE FOR THESE RECOMMENDED BY THE FORUM?

I will be sending the engine cases to Electron Beam Engineering for vapor blasting ($100) unless there is a recommended shop from this forum.

All input is appreciated.

Thanks!

Paul
 

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Discussion Starter · #4 ·
Thanks Tools,

just did the prelim clean/degrease on the 1970 engine cases and have the 1972 already done. I understand that vapor blasting does not work well on the shellac gasket sealer which I'm pretty sure I have on the 1970 case. I'm told a razor blade is needed for that stuff? The 72 was rebuilt, very poorly, and re-asembled with silicone. Can you advise on anything in particular I should look for in determining which set of cases to be done?

What do you charge for a head rebuild and what is included? I'm looking at new valves and springs and I'd like to get the outside prep'ed for paint.


Love to be able to work with a member.

Thanks!!!!
Paul
 

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I do have access to a "hot tank" type cleaner that uses a high pressure spray of really hot water with a cleaning chemical that removes everything from the cases. I have this done to engine cases and other engine parts when I rebuild an engine. The only thing that vapor blasting does better then this process is that it will remove staining from the aluminum. However if you are going to paint the cases, that would not matter.
For boring/honing cylinders I charge $35.00 a hole unless I have to cut more then 1mm. Heads I start at $45.00 to do 2 valves. This is to clean/beadblast the head, cut the valve seats, grind, or replace the valves, and replace/install the valve guide seals. If seats, or guides need replaced, that is extra.
As for deciding which parts to use, the only advice I have is to thoroughly look them over for damage.
TOOLS
 

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Discussion Starter · #6 ·
Thanks Tools1
I should be able to start the inspection process this weekend and will select which head I want to run with. I may need some advise on where to source the replacement valves, guides, springs.

Thanks!

Paul
 

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Well, I'm glad to have seen this thread!
I'll PM you later this week about sending some parts your way!



I do have access to a "hot tank" type cleaner that uses a high pressure spray of really hot water with a cleaning chemical that removes everything from the cases. I have this done to engine cases and other engine parts when I rebuild an engine. The only thing that vapor blasting does better then this process is that it will remove staining from the aluminum. However if you are going to paint the cases, that would not matter.
For boring/honing cylinders I charge $35.00 a hole unless I have to cut more then 1mm. Heads I start at $45.00 to do 2 valves. This is to clean/beadblast the head, cut the valve seats, grind, or replace the valves, and replace/install the valve guide seals. If seats, or guides need replaced, that is extra.
As for deciding which parts to use, the only advice I have is to thoroughly look them over for damage.
TOOLS
 

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Likewise.
 

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Discussion Starter · #10 ·
I'm a rank amateur when it comes engines (especially motorcycle engines) so I automatically assume that new is better than re-using when it comes to stuff like this. I know the guides are worn and I may have one spark plug hole that needs some attention which I just discovered. I'm also considering having the cam and rockers re-worked. It looks like the cams from both engines are well worn. The rockers are not as evident (to my eye) but if I do the cams I might as well do the rockers. I don't have a valve spring compression tool so I can't say if the springs need replacing yet. I hope to pop the valve retainers this weekend using a hammer and socket.

My primary concern is to have a reliable engine when I'm done and one that I can ride confidently at it's upper performance level. I'm a firm believer in the adage that it's more fun to ride a slow bike fast than a fast bike slow. Thats what this build is all about.

At the same time I don't want to just throw money at the project and it's really important to me that I assume as much of the work as I am capable of and because I want to learn more I tend to push my capabilities.....I just need to understand where I need to let professionals help out. Valves and cylinder/pistons are obvious.

Right now my plan is as follows:

Get the cam and probably the rockers rebuilt.
Sent this stuff to you with the head I select to have the valves cut and at the very least new guides installed. I'll also send you the engine cases for hot dip.
Send the cylinders to Bore-Tech for the Carbide bore and help with piston selection
Then I need to figure out what I want to do the the cam chain tensioner. I know there is an aftermarket system available but I don't know much about it verses using a new, OEM set up.
Once this is done I'll do the assembly of the engine/tranny then work on the carbs, electrical etc. etc.

I do need to stick to some kind of budget but I don't have a time frame so if I need to invest in professional help I'm fine with that; it will just take a bit longer to complete the project.

So to answer your question...I'm not sure if I need new valves/springs or not...I'll probably leave that up to you if you are will to make a judgement.

Sorry to be long winded here. It's a big project to me and I'm at the very starting phase.

Thanks!

Paul
 

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I understand and I am in a similar position. I can do what I can by following the service manual, but anything requiring special tools and machining/inspecting to fine tolerances, I would rather leave to a professional.

I hope to apply the "buy once cry once" rule to my project, so that I do a costly but thorough job the first time around with the engine apart and removed from the bike, so that I don't have to do it again for something that I missed or was too lazy/cheap to fix.
 
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