Topic: CB350F piston size

[Cvillechopper]

I'm just getting started pulling parts together for my 350F rebuild but haven't been able to find a set of 2nd step pistons and rings.  Anyone know the std dimensions for the 350f?  I'm thinking I might be able to use a set of 400f pistons since I will have to have the jugs sent to be bored anyway. 

Thanks
James

[ttr400]

CB350F std piston is 47.00mm.
CB350F cyl sleeve OD 55.00mm upper, 54.3mm lower.
CB400F Piston 51.00mm.
CB350F pistons are discontinued and very hard to find. plus they have a one piece oil ring.
CB400F pistons are still available and have a better 3 piece oil ring.

Yes you can just fit the CB400F Std 51mm piston, this will be the maximum you can go and will give you a sleeve wall thickness of 2.0mm on the upper and 1.8mm wall on the lower part of the sleeve.

It is possible to fit the CB400F sleeves, but boring and machining of cyl and upper crankcase is required for them to fit. but then you can go up to a 54.5mm yoshi or Wiseco piston kit.

Or fit the complete 400F cyl and head. would still have to open up the crankcase. Plus replace the 2 front middle cyl studs for custom items.

Or I make custom sleeves for the CB350F cyl block. still have to machine to fit etc.

Hope that helps a bit with your decision.

Kevin

[Cvillechopper]

CB350F std piston is 47.00mm.
CB350F cyl sleeve OD 55.00mm upper, 54.3mm lower.
CB400F Piston 51.00mm.
CB350F pistons are discontinued and very hard to find. plus they have a one piece oil ring.
CB400F pistons are still available and have a better 3 piece oil ring.

Yes you can just fit the CB400F Std 51mm piston, this will be the maximum you can go and will give you a sleeve wall thickness of 2.0mm on the upper and 1.8mm wall on the lower part of the sleeve.

It is possible to fit the CB400F sleeves, but boring and machining of cyl and upper crankcase is required for them to fit. but then you can go up to a 54.5mm yoshi or Wiseco piston kit.

Or fit the complete 400F cyl and head. would still have to open up the crankcase. Plus replace the 2 front middle cyl studs for custom items.

Or I make custom sleeves for the CB350F cyl block. still have to machine to fit etc.

Hope that helps a bit with your decision.

Kevin

Awesome!  That's what I was looking for plus some.  I thought about using a 400f cylinder and head but am trying to avoid buying ANY unnecessary parts since we have a little one on the way.  Looks like a set of 400f std pistons and rings will be the answer.  Thanks Kevin.

[Trevor from Warragul]

Here's where to buy oversize pistons:

http://www.cmsnl.com/products/piston-100-repro_06135333000p/

Trevor

[camelman]

I bought a couple sets of pistons from those guys.  I can vouch for their components being good quality.

Camelman

[Cvillechopper]

I just came up with another potential option.  Honda CL90 pistons are 49.90 std.  I can get these much cheaper than I can 350F or 400F pistons.  I've been searching for some dimensions (dome height, wrist pin size, skirt, etc) to compare these to the 350 ones with no luck so far.  Anyone have a suggestion on where I might be able to find out if these will work?

[Tretnine]

James you cheeky boy. Starting a build with a baby on the way? If I had known I would have been hassling you for help with my 550 build. Maybe just to use your parts washer...

[jessezm]

I've got a set of CB400f pistons that came out of my bike (replaced with 54.5mm pistons).  They are fabulous shape--the bike only had 5k miles on it to start.  If you are interested, let me know.  I can send some pics in a day or so.  I've got the pins and clips as well (though you will probably want new clips), and all of the rings are still installed except for one that I snapped.

[Cvillechopper]

James you cheeky boy. Starting a build with a baby on the way? If I had known I would have been hassling you for help with my 550 build. Maybe just to use your parts washer...

LMAO!  Not even close to truly starting a build.  Just in the accumulating parts stage (predicted to last at least a year) while I can still find/afford them.  You're welcome to use the parts washer.  It's just a bench right now...

[Tretnine]

I'll try to give you a ring sometime soon. My motor will be in bits in a week or two then it's time for frame work (hopefully some welding.) painting, washing boring... oh the excitement!

[Brremi]

Here's where to buy oversize pistons:

http://www.cmsnl.com/products/piston-100-repro_06135333000p/

Trevor

As I understand it the 400f std pistons fit 350f without bore. Is the link you posted for the 400f std piston kit?

thanks

[Trevor from Warragul]

It was a link to a CB350F oversize kit.

Your best bet is now these guys (despite them being cheap they are good quality):

http://www.ebay.com/itm/72-74-HONDA-CB350F-0-5mm-47-5mm-OVERSIZE-PISTON-SET-Four-Pistons-are-included-/130936212986

[Powderman]

Here's where to buy oversize pistons:

http://www.cmsnl.com/products/piston-100-repro_06135333000p/

Trevor

As I understand it the 400f std pistons fit 350f without bore. Is the link you posted for the 400f std piston kit?
The repro piston would be a 48mm 1st overbore size. If you use that piston you will have 346cc.

thanks

The 350 bore is 47mm, stock bore on the 400 is 51mm. No way will it work without boring.