Topic: Are the 500 and 550 blocks the same?

[Celco]

Looking to start up a gentleman's express build on a motor of mine.  I have the 550 lower end, the 500 top end but the cylinders were a little scored up. 

Instead of looking around for a 550 block, hoping that the 500 block I have (that needs machining anyways) will work to be bored out to 61mm, and mate with the other 550 parts.

Anybody know the answer to that?

[DavePhipps]

From what I rememer the 500 sleeves are a bit thinner. The easiest fix would be to get 550 or 750 liners. The 750 sleeves would need to be made shorter to fit, but then you would have a 61mm bore. This was covered somwhere in the forums but I can't find the thread right now.

[Celco]

If the sleeves are thinner in the 500 does that mean the stock ID on the block is going to be smaller in a 500 block than compared to the 550 block.

[Hannibal Smith]

On my "Henry Abe" kit with 61mm pistons, it came with brand new liners for the CB500 if I am not mistaken-

[TwoTired]

I don't believe the cb500 Cylinder block contains sleeves that can be bored for 750 pistons.  The Cb550 cylinder block can be bored.

The "605" kit for the CB500 came with replacement sleeves.  Bore the block, insert the new sleeves, and then bore the sleeves for the new pistons.

[DavePhipps]

I do know that using 61mm pistons in the stock 550 sleeves leaves you with a 1mm thick sleeve. What is the diameter of the sleeves on the 500 (ruler or caliper time)? I would check my 500, but I have no desire to dismantle my topend.

[Celco]

I do know that using 61mm pistons in the stock 550 sleeves leaves you with a 1mm thick sleeve. What is the diameter of the sleeves on the 500 (ruler or caliper time)? I would check my 500, but I have no desire to dismantle my topend.

Haha, I have a 500 top end in a box downstairs I can check.... its just all boxed up.

[DavePhipps]

I've got the 550 head at my ex-wifes barn. I'll see if I can get a measurement from that to compare.

[Hannibal Smith]

My cylinder walls measure 1.63mm on my bored out CB550, piston diameter is 61mm.

The CB500 cylinders I have measure 1.5mm, but what you see is not what you get, so to speak.

The CB500 liners run 4.08mm wall thickness inside the cast cylinder block, only the last 20mm or so runs at 1.5mm, and the piston ring area never gets this low. These liners are punched out for 61mm pistons.

[DavePhipps]

Sorry I didn't get a chance to measure mine this weekend. Youngest son and I are sick and moping around the house.

[jimtt]

I am not sure I understand your question; so my answer may be off base. The 500 cases will not accept 550 cylinders; this information should be added to what is said above. JIM

[bryanj]

500 block can be bored to 61mm BUT only by a VERY carefuland experienced machinist as the bottom of the liner gets very thin---better to use a 550 block