CB160 big bore to 175

[Jlovvorn]

I just picked up a cylinder and piston kit to take my tired CB160 engine out to 175.

It's basically a 2.0 over kit.

Anyone have any experience with this modification, or concerns?

Seems like I should be able to just tear down the engine, swap in the cylinder and pistons, and put it back together.

Thoughts? Warnings?

[G-Man]

You might encounter a little clearance problem between the larger pistons and cylinder head. A 175 head does not have the cast iron 'skull' so may be slightly different.

With only 2mm you should be OK. You might need to re-jet the carbs, also.

G

[kirbb9]

If you bought liners then you will have to press your originals out and then have the
cylinder bored to fit the new liners.

Brady

[Jlovvorn]

I bought a cylinder with the 2.0 over sleeves already installed, with matching 2.0 pistons and rings.

I am hoping I can crack it open, swap the cylinder and pistons, button it up and be on my way.

It's running strong now with no smoke and 155 each side, so I am a little reluctant to mess with it.

I wonder how much I would notice the upgrade in terms of acceleration and top speed.

Not sure it's worth it.

[kirbb9]

Okay, that should work, and I agree I would hate to tear that motor apart at this time.

Brady

[Jlovvorn]

I assume this thing has a nice long shelf life. And I have a spare 160 frame and a lot of parts. Maybe I will start building a racer.

[teazer]

2mm were offered as a big bore modification and can be bored into stock liners. The crown is fine - if it's a big bore 160 and not a 175 piston.

175 pistons won't fit inside a 160 head.

If your motor is running 155 psi on both sides, I'd keep those pistons on the shelf for the day they are needed.