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Discussion Starter #101
I didn't get nearly as much time to work on the bike over the holidays as I had hoped but I was able to make a little progress.


I was finally able to wrap up the front brakes. The first brake cable I had installed (a reproduction cable purchased from Scrambler Cycle) broke the first time I squeezed the lever. I’m just glad it happened in the garage and not out on the road. I purchased and fitted another reproduction cable from David Silver Spares.

After the brakes had been adjusted I installed a 530-H chain from RK and reinstalled the chain guard.

Next it was on to the exhaust. The original headers and mufflers were not salvageable but I was able to source a used set of headers for cheap on eBay. Unfortunately they are in pretty rough shape so I am still on the hunt for better set. I’m using a pair of Emgo Dunstall replica mufflers that I had on hand from a previous project and I was able to modify the included brackets and mount them to an existing mounting point on the frame. The right side was very straight forward but the left side was contacting the crankcase. It turns out that the header I was using on that side is slightly bent.





 

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Discussion Starter #102
I finally got the exhaust sorted out. What a battle. I ended up purchasing another set of reproduction headers. This time from an eBay seller out of Thailand and to my great surprise they are damn near perfect. I also purchased a new set of the same Emgo mufflers that I was mocking up with and for whatever reason they fit quite a bit better. The reducer shims in the new set are a bit different than the old set I had. I know they are a far cry from the stock CB77 mufflers but they will do the trick for now. I'm anxious to hear how they sound.




 

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Discussion Starter #103
It runs!

We got a rare break in the weather on Monday and I was finally able to pull the CB77 Super Hawk out of the basement and into the sunlight for the first time in several years. The bike fired up without much fuss or major issue. It's running very rich and there is a small oil leak but I'm hopeful that these issues can be resolved without too much trouble.

 

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Discussion Starter #104
I lowered the engine out of the frame a bit and re-torqued the head nuts. It did lessen the oil leak from under the head a bit but did not resolve it completely so I'm thinking the head may need to come back off.

I'm still doing some fine tuning on the carburetors. It seems to be running rich no matter what changes I make. Mixture screw seems to make no difference. I adjusted the float height from the specified 22.5mm all the way up to 26mm just to see if it would make a difference. It did, but it's not a solution. I'm going to dig the old jets out of the parts bin and give them a try. I've had rebuild kits in the past that were too far out of spec and caused running issues so I'd like to rule that out before going any further.

On the upside there were no chunks or shavings of metal in the oil after it's initial run.
 

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I had a set of those Emgo mufflers on a Triumph once, it would barely run. Opened up a few of those blanked off tubes in the end of the mufflers with a drill and it ran quite a bit better.
 

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Discussion Starter #106
I had a set of those Emgo mufflers on a Triumph once, it would barely run. Opened up a few of those blanked off tubes in the end of the mufflers with a drill and it ran quite a bit better.
I hadn't even thought about the mufflers to be honest. I'll add those the list. I pulled the carbs again and adjusted the float height to 24mm. Still out of spec but I want to try that with a fresh set of plugs as it's one of the easier adjustments to make. It doesn't help that the weather keeps swinging so much. One day it's in the 40s and dry, the next in the 60s and damp, etc. We're supposed to be near the 70s towards the end of the week. For now I've jumped back over to my CB160 project.
 

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Discussion Starter #107
I pulled the CB77's engine over the weekend to investigate the oil leak that some of you may have seen in the Part 11 video I posted. My hope was that I had made a simple mistake like forgetting the o-ring that goes around the dowel pins. No such luck.

You can clearly see in the pic below that a significant portion of the head gasket was not making good contact between the surfaces. The oil leak was coming from the front right (bottom left in the pic).



Below is the cylinder head side. Notice how clean the gasket came off on the "bad" side.



And here's the problem, I'm assuming. The cylinder sleeve is raised above the deck surface. Shouldn't the sleeve be flush with the head surface? This would explain why compression was fine but I was getting the oil leak.

Is this a common issue? What are my options?



 

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Support the cylinder casting on firebricks on a cookie sheet in your oven.... place a brick on the raised liner....heat.....
Aluminum expands faster and weighted liner drops into place (assuming no grit/rust beneath it....) .......
I would partially drop liner out, clean up under the lip, and THEN reinstall.........
Please phone for additional steps and hints as too much to type.......
 

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Discussion Starter #109
Support the cylinder casting on firebricks on a cookie sheet in your oven.... place a brick on the raised liner....heat.....
Aluminum expands faster and weighted liner drops into place (assuming no grit/rust beneath it....) .......
I would partially drop liner out, clean up under the lip, and THEN reinstall.........
Please phone for additional steps and hints as too much to type.......
Thanks. I'll try to give you a call this evening.
 

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Mike,
Here is a photo of a cylinder sleeve in the aluminum casting for a Webco/Forge True 350cc kit. They are definitely flush, this assembly was carefully lapped.
Mark
309172
 

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Discussion Starter #111
Mike,
Here is a photo of a cylinder sleeve in the aluminum casting for a Webco/Forge True 350cc kit. They are definitely flush, this assembly was carefully lapped.
Mark
View attachment 309172
Thanks for the reference pic. I'll let you know how this turns out.
 

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Discussion Starter #112
First off, Steve, thank you for taking the time to talk me through this process, I really appreciate it.

I was 50% successful. Fortunately, it was the 50% that really mattered. Only one of the cylinder sleeves dropped out but is was the problem cylinder so I'm going to call it a win. I heated the cylinders in the oven at 350 deg. and after about 30-40 minutes the right sleeve dropped out. The other one did not. Out of curiosity I let the everything cool down to room temp and tried the process again at 400 deg. No luck. I even gave it a few knocks with a scrap 2x4 from time to time but it didn't budge. I've decided not to press my luck. I don't need the other sleeve out for this fix.





 

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Discussion Starter #113
Well, I suppose it would be out of character for this bike to cooperate, so I shouldn't be surprised that upon re-seating the cylinder sleeve, the issue persists. Here's where I'm at this morning:

I got started early and with a little more persuasion this time, fully removed the right cylinder sleeve. After last night's failed attempt at getting things seated properly even after a thorough clean of the groove and sleeve lip, I wanted to make sure that the groove depth and sleeve lip were even the same. They are not.



I flipped the sleeve upside down and as you can see, the lip is taller than the groove in the cylinder body. My uneducated guess is that this sleeve (at the very least) is not original and whoever replaced it did not have it machined down to match the surface of the cylinder body.





I need another cup of coffee before I start making any decisions, I just wanted to let you folks know where this little experiment is at.

The things we do for these old bikes...
 

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Discussion Starter #114
Quick update on the cylinders: I decided to attempt to shave down surface of the cylinder lip myself. I figured that worst case I was going to need to send everything out to a machine shop anyways so why not give it a shot. Pics and video below. I'm 95% confident that it's going to work. I have the engine back together at this point but ran out of time yesterday and wasn't able to get it back in the frame. Hopefully in the next day or so I can put the bike back together and start it up. I won't know if the leak is fixed until that point.










 

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I had thought to stop the leak you would need a thicker O-ring around the head through-stud. Hadn't realized you could get the liner out.
Great work.
 

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Discussion Starter #120
I had thought to stop the leak you would need a thicker O-ring around the head through-stud. Hadn't realized you could get the liner out.
Great work.
The whole time I was pulling the engine and disassembling I was hoping I had simply forgotten the o-ring. This project has been quite a learning experience for me.
 
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