Topic: '82 CB650 Project

[ThePwninator]

Hi everyone

Picked up this bike in late november and have been working on it on/off since.
It's been sitting in cold storage since 1995 and as i have discovered working on it, time really has taken its toll when it comes to corrosion and general wear.
The plan is to first get her running and then try some light cafe mod before putting her back together




Work in progress or work I have infront of me (or have completed to some degree):

• Carb breakdown and rebuild
• Front Brake caliper rebuild
• Starter restoration - It's rusted shut
• Engine vapor blast - The amount of corrosion on the alu is pretty massive
• Top end rebuild - massive oil leaks around the top and cylinder block.
• Starter clutch rebuild
• Front fork new seals/rebuild
• Steering stem bearings
• Electrics

Will keep posting some pics of work that has happened up until where I am now with the engine rebuild!

[ThePwninator]

Picked up a carb rebuild kit but ended up just replacing all the seals and the "T-joints" that were cracked.
I will probably need to come back for re-jetting but for now i kept it stock

Carbs in dire need of cleaning


At least the internals looked pretty good


I bought new felt seals a well. The old ones where in not so good shape 




Putting em back together! (yes, i know they don't go together like this. was a temporary fix to hold the pairs  )

[ThePwninator]

Next up i did the front brakes. I unfortunately don't have many pics from the before stage but lets just say they were in bad shape...

The calipers were badly pitted so replaced those together with all the other internals


Old and new


Going in for paint in my near-pro paint booth... I used VHT caliper paint


Finished product. Not sure about the durability of the paint but we'll see...

[tourmax]

none of the pics are showing?

[ThePwninator]

none of the pics are showing?

Oh really? Strange, they show up fine for me. Thanks for the heads-up, will look into it!

[tourmax]

none of the pics are showing?

Oh really? Strange, they show up fine for me. Thanks for the heads-up, will look into it!

You probably are seeing the pictures because your comp would have saved them in cache (from uploading them), but others won't see them because (obviously) they don't have them in the browser cache.. See if clearing your cache makes them disappear....

[ThePwninator]

none of the pics are showing?

Oh really? Strange, they show up fine for me. Thanks for the heads-up, will look into it!

You probably are seeing the pictures because your comp would have saved them in cache (from uploading them), but others won't see them because (obviously) they don't have them in the browser cache.. See if clearing your cache makes them disappear....

Have now tested the page with different devices and have had some friends confirm they can see the images. I tried re-uploading the images to another place with simpler filenames. Is anyone else viewing the thread not seeing the images?

[ThePwninator]

Continuing hoping the images will show 

Next up i tackled the starter which was a mess and rusted completely shut. When i opened it up it looked more like a lost anchor found at the bottom of the sea than a starter engine 
Don't have great pics of this unfortunately cept this one:
 


However upon measuring it all up the internals all seemed to still be connected and functioning so with a lot of elbow grease i cleaned it up best i could and put it together again
Here is a movie of it spinning up!

https://www.dropbox.com/s/n2hkv3lpmfjqo6r/StarterWorking.mov?dl=0

[tourmax]

none of the pics are showing?

Oh really? Strange, they show up fine for me. Thanks for the heads-up, will look into it!

You probably are seeing the pictures because your comp would have saved them in cache (from uploading them), but others won't see them because (obviously) they don't have them in the browser cache.. See if clearing your cache makes them disappear....

Have now tested the page with different devices and have had some friends confirm they can see the images. I tried re-uploading the images to another place with simpler filenames. Is anyone else viewing the thread not seeing the images?

It seems the problem was on my end. I started turning off browser tools and when I turned off "privacy badger", the pictures showed.

Seems a bit strange as this is the only site (and webpage on the site) that behaves this way.....weird.

[ThePwninator]

Ah great. Glad ot hear it all works now

[ThePwninator]

After all that i started to pull the motor out of the frame.

Decided to pull it piece by piece rather than one chunk since it was going to be vaporblasted


Case had seen better days. Unfortunately some pitting of the aluminum as well as just crust and paint peel


Managed to drop the cylinder on my workbench breaking of one of the fins...


Crusty valve. Needs replacement...


Polished it up just to see. Not the greatest shape



Next up was sending the engine for vapor blasting
That will catch us up to real time and when MY PROBLEMS STARTED 

[ThePwninator]

Ok so up until now things have been going pretty good. Crust and corroded bike yes but still more than salvageable
I decided to send the engine out for vapor-blasting and to repair the broken fin.

The broken fin was a success. some nice metalwork from the shop


Some shots of the engine after blasting. Overall i think they managed to get a decent finish.





Now on to the BAD...  The mating surface of the the head is in really bad shape



The cylinder is not great either


This is beyond my skill level to fix so i could use the forums opinion on these ones... Are they salvageable or am i now in possession of a solid piece of aluminium junk?
I think i should be able to machine the head but what about the cylinder? Do i need to pop out the cylinders in that case and what tolerances do i have to work with for both pieces?
Or just a lot of copper paste?! 

Help please!

[fizzlebottom]

See how far a machine shop needs to mill the cylinder head. The book says the spec limit is 0.25mm. I'm not certain if that means you can take up to 0.25mm off, or if there needs to be at least 0.25mm left to remain usable.

I can't tell from the pic how much damage there is to the cylinder deck. You may be able to deck that as well or use some copper gasket spray on the new gasket to add a little bit of filler material. Not really the greatest option, but you do what you have to do.

The other choice is to sit on ebay and hunt for better parts. it undoes some of the vapor blasting you had done and you risk getting #$%* parts again. Tough spot.

See what a machine shop can do for you.

[SOHC4 Cafe Racer Fan]

WOW. I'm surprised that those unexposed surfaces are so pitted. You might want to find a spare head and jugs if decking is not a suitable option.

[ThePwninator]

See how far a machine shop needs to mill the cylinder head. The book says the spec limit is 0.25mm. I'm not certain if that means you can take up to 0.25mm off, or if there needs to be at least 0.25mm left to remain usable.

Thanks. Yes, I saw that too. Took it to mean that the largest allowed warpage is 0.25 across the surface (when checked with feeler gauge). In this case the head is pretty straight but the pitting def exceeds 0.25mm.

WOW. I'm surprised that those unexposed surfaces are so pitted. You might want to find a spare head and jugs if decking is not a suitable option.

Thanks. Yup, i felt the same way. It looked like the old gasket had really eaten into the metal 

[tourmax]

have the head and cylinder block skimmed and see where you end up. The important part for sealing is where the head gasket fire rings crush between the head and block and on these engines it's also important in the oil passage o ring seals.

The rest of the surface isn't as critical, as long as it's not warped.

Myself? I'd look for a set of cylinders and heads that are in better shape and go from there. The cylinders are pretty cheap used (just picked up a near pristine set off ebay for 50 bucks) and the heads aren't a lot more. Try to get a head which still has the cam cover with it. They can be mixed sets, but a matched set sets you up for success on a rebuild when you're talking about used parts that have bearing surfaces that usually wear evenly across their service life.....

[ThePwninator]

The cylinders are pretty cheap used (just picked up a near pristine set off ebay for 50 bucks) and the heads aren't a lot more.

agh, wish I lived on this market. The best I can do here is way north of a 100 

[tourmax]

The cylinders are pretty cheap used (just picked up a near pristine set off ebay for 50 bucks) and the heads aren't a lot more.

agh, wish I lived on this market. The best I can do here is way north of a 100 

That was off ebay. Have a dig around and see what you can find.

Since you're got it torn apart, you may want to explore putting cb750f pistons in it. The cb650 liners will take the 61mm pistons easily and it give you an actual 657 cc's instead of the stock 626 cc's. You can even use "used" pistons, but you need to have some machine work done to them to fit the deck height and comb chamber shape. The machining is actually pretty easy, biggest PITA is finding a shop that either has the piston holding fixture or is wiling to make one....

[ThePwninator]

The cylinders are pretty cheap used (just picked up a near pristine set off ebay for 50 bucks) and the heads aren't a lot more.

agh, wish I lived on this market. The best I can do here is way north of a 100 

That was off ebay. Have a dig around and see what you can find.

Since you're got it torn apart, you may want to explore putting cb750f pistons in it. The cb650 liners will take the 71mm pistons easily and it give you an actual 657 cc's instead of the stock 626 cc's. You can even use "used" pistons, but you need to have some machine work done to them to fit the deck height and comb chamber shape. The machining is actually pretty easy, biggest PITA is finding a shop that either has the piston holding fixture or is wiling to make one....

Thanks, yea i think at this point i just want to get it back together stock


On the head topic, does anyone know the actual clearance on these things? How much can i get rid off without messing with valves etc?

[fizzlebottom]

This thread says 1mm

http://forums.sohc4.net/index.php?topic=44595.0

[ThePwninator]

This thread says 1mm

http://forums.sohc4.net/index.php?topic=44595.0

That thread seems to be about installing 750 pistons though

[fizzlebottom]

This thread says 1mm

http://forums.sohc4.net/index.php?topic=44595.0

That thread seems to be about installing 750 pistons though

Ah yeah, details I read past. 1mm off the dome for the CB750K pistons. He doesn't mention specific machine work for the CB750F pistons. Either way, you have options but both will require machine work.

[ThePwninator]

Finally back with this project after a bit of a rough year.

Started to reassemble the engine!



All gears seem to be there upon a bit of testing
https://www.dropbox.com/s/6lvtlhtvbi6nw4e/2023-02-16%2010.45.06.mov?


I have a question for these guys. There is no torque specified for them so wonder if anyone knows? I did them to 10 now. Also should I dab some blue loctite on them? Same question for the primary chain oil nozzle...




Now waiting for some parts before moving on to installing the crank!