Is this Toast?

irk miller

You've been mostly-dead all day.
DTT BOTM WINNER
Right, what I'm suggesting as a possibility is swapping the good sleeves into the better cylinder casing. I did this on my CB650 engine.

 

SONICJK

Reminds me of...me No, I'm sure of it. I hate him
CALfeRacer said:
Bumping this thread instead of making a new one... taping everything up to go out for media blast and noticed this. It’s where the chain tensioner mounts. Should I just slather some JB weld in there or is this Toast?
I do have another set of cylinders, but the bores are gross and would need to be bored out for the bigger pistons (unlike this set of cylinders).
I would personally not install that. That little cracked chunk looks ready to break off and destroy your engine while it's getting ground to bits by the crank and transmission.
 

Brent

Member
Not worth risking that piece holding. "You can pay me now or pay me later", a little now or more later.

If you swap sleeves make sure the direction of travel is the same.
 

SONICJK

Reminds me of...me No, I'm sure of it. I hate him
Agreed. If that little chunk breaks off and lodges in the transmission at 70mph you'll really be wishing you had not put it back together that way lol
 

CALfeRacer

Fat man on a little bike
irk miller said:
Right, what I'm suggesting as a possibility is swapping the good sleeves into the better cylinder casing. I did this on my CB650 engine.

How hard was that? I assume throwing them in the oven to pop out sleeves and then freezing the good ones to put back in?

Debating just getting the “bad” set machined since pistons are .050” over stock anyways.
 

CALfeRacer

Fat man on a little bike
SONIC. said:
Agreed. If that little chunk breaks off and lodges in the transmission at 70mph you'll really be wishing you had not put it back together that way lol
I’ve already blown up one engine going 70, and I’d like to avoid doing that again
 

irk miller

You've been mostly-dead all day.
DTT BOTM WINNER
That was the first time I swapped sleeves. Every other time, I have sent them out to be bored. On the 360s, i take it as an excuse to do the GS piston 378 bore. It really is pretty quick and easy. I have kilns, so I put it in my kiln until the thermo couple read 350°F. The cylinder body was up on refractory bricks to where the 3 good cylinders were directly on top of the bricks and the bad cylinder was open underneath. A very light tap with a brass hammer and the bad sleeve slid right out. I had the good sleeve in the freezer just long enough to be ice cold to the touch, so not a crazy amount of time. Same deal. Heated the body up to 350° and dropped the cold sleeve right in. It took zero effort. Just slid in.
 

SONICJK

Reminds me of...me No, I'm sure of it. I hate him
irk miller said:
That was the first time I swapped sleeves. Every other time, I have sent them out to be bored. On the 360s, i take it as an excuse to do the GS piston 378 bore. It really is pretty quick and easy. I have kilns, so I put it in my kiln until the thermo couple read 350°F. The cylinder body was up on refractory bricks to where the 3 good cylinders were directly on top of the bricks and the bad cylinder was open underneath. A very light tap with a brass hammer and the bad sleeve slid right out. I had the good sleeve in the freezer just long enough to be ice cold to the touch, so not a crazy amount of time. Same deal. Heated the body up to 350° and dropped the cold sleeve right in. It took zero effort. Just slid in.
Yep, I've had them drop out during powdercoating so it doesn't take much to get them out when it gets hot!
 

CALfeRacer

Fat man on a little bike
Good to know! We’ve got a little oven at work I might be able to use, it claims to run up to 450F (I’ve only used it up to 200F). Although I should probably check with the boss man first since we normally use it for conditioning wood samples, might not be great to contaminate it with oil.
I’m also going to look over the cylinders again closely, might just be worth it to have the other set bored out anyways.


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CALfeRacer

Fat man on a little bike
Also, the GS piston swap is only for the 360 right? For some reason I feel like back in the day when I was first “planning” this build I read that it didn’t work with the 350 for some reason.


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irk miller

You've been mostly-dead all day.
DTT BOTM WINNER
CrazyPJ is the man with the knowledge on that, but if I were making bets, I would say it doesn't work because of the stroke or something down that line.
 

CALfeRacer

Fat man on a little bike
Maybe I’ll go back and dig around to see if I find something.
As far as my current situation, I’m going to need to swap the sleeves or find a new set, the set in the good jugs are toast. The 0.50 pistons I have slide in easily, with the rings on them. I have no clue how the 0.25 pistons that were in there did anything. Maybe that’s why it was parked


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ex119x

Member
The wrist pin diameter is 1mm smaller on the 350 compared to the 360. 15 vs 16 i think. I believe GPZ750 pistons can be used as a big bore for the CB350. I have never tried it, but have been meaning to. I think the regular KZ750 will also work but are a lower compression.
 

CALfeRacer

Fat man on a little bike
Thanks for the help everyone! Good cylinders are in the good (but very dirty) jugs. Second pic shows my setup, we don’t have any bricks so unistrut had to do. All of them dropped right out, except one of the good cylinders which took a few light taps to get out.
 

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CALfeRacer

Fat man on a little bike
Back again... building the engine and realized the tops of the sleeves don’t sit flush with the cylinders. Assuming this isn’t right, do I need to drop them out again and do a better job of cleaning the space between them or is this something where I just need to take it to a machine shop and have them flatten everything?


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Pete12

Member
When you install the sleeves you need a light press on the top of them to ensure that they don't pop back out while cooling, looks like that's what happened to yours. Alternatively you can fabricate a jig that holds them in place, but don't put too much weight on it.
 

CALfeRacer

Fat man on a little bike
We’ve got a bunch of steel blocks/spacers etc. for test fixtures, think I could get away with just putting a couple blocks on top of the sleeves to hold them down while heating/cooling?


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teazer

Well-Known Member
DTT BOTM WINNER
Exactly. Without pressure, the sleeves creep up and if you machine the tops, they fall back down in use and the head gasket leaks.

You can also just press them into place in a hydraulic press. Don't go mad though.
 

CALfeRacer

Fat man on a little bike
Good to know. Don't have access to a hydraulic press so I'll just plan on using the same setup as before but put some blocks on top of the sleeves to seat them down.

On another note, anyone input on the best way to clean up the bores? They were machined before I bought them, but have been sitting for 5 years or so and I want to clean them up before install. I saw common motor collective has a dingle ball hone for the 350, but wondering if it's going to be significantly better than just a 3 stone hone/deglazer from autozone/harbor freight. Any thoughts?
 

CALfeRacer

Fat man on a little bike
Here’s the new setup. Let the furnace get up to about 350 with the cylinder in there, then put the steel block on top. Gonna let it sit at temp for an hour or so, then turn it off and furnace cool. Hopefully it works!
 

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