Topic: 836 Piston ID help. ART? cb350?

[wiskey]

I purchased these along with with matching jugs from someone locally on craigslist.

I believe they came from a 76 CB750 and I want to put them in my 77

From what I have read possibly 350 pistons? only marking is the "ART" stamp.

I do measure ~65mm with a pair of calipers. which throws me off, I thought the cb350 were 64mm.

If they are any good I would like to know what Rings to buy to freshen it up.

any help would be great. Thanks!

[Jerry Rxman Griffin aka MuthaF'er]

Don't think those are actual Honda pistons especially with ART on them vs Honda. 350 are 64mm. 64mm used in a 750 = 812. 4th over 350 rings = 65mm = 836 and would work provided the land/ring grooves thicknesses are the same. 1.5mm, 1.5mm, and 2.5mm

[wiskey]

Anything I should to do to bring these pistons back to life?

Was just planning on replacing the rings and honing out the bore.

[kmb69]

That was THE GIG back in the early days. Machine 350 piston crowns and skirts for 811 and 836 big bore kits.

ART is the largest piston manufacturer in Japan. Nearly all Honda pistons are manufactured by ART and nearly all of them have the ART designation cast on the piston.

[wiskey]

Thanks, so its safe to say I can use 4th over 350 rings?

[kmb69]

Double check the groove widths as Jerry suggested to be sure. If the cylinder bores are "straight" without "scratches", I would suggest to just de-glaze. Don't hone too much.

To do it "proper", you need to check the cylinder to piston clearance, installed ring end gap, ring side clearance to piston, and piston pin bore, and piston pin diameter to be sure all falls within spec.

[wiskey]

will do thanks!

Any reason I cant run cylinders & pistons from a '75k in my 77k?

[MCRider]

Right, those are 4th over, or S4, or +1mm, or however you want to say it, 350 Honda pistons. Sourced from ART.  That's the kit the bike in my avatar had in 1971. I was working in a Honda Parts Dept at the time. The rings in our Honda parts boxes fit. 

But you'll have to check yours specifically of course.

I thik the insides are machined out a little, and maybe the dome is taken down some I forget exactly.

[wiskey]

thanks! great info. Any idea what the compression ratio is? 10.25:1? and would I be able to run a hotter cam without machining the pistons?

[MCRider]

thanks! great info. Any idea what the compression ratio is? 10.25:1? and would I be able to run a hotter cam without machining the pistons?

I don't remember in my case, but I'd say at least 10.25:1. I used a K0 stock cam in mine. It ran great. But for bigger bumps you may not get first hand knowledge and you'll have to "clay" the pistons.

[Big Jay]

It would be interesting to see the dome after it was clean.  I don't believe we made those as the bottom is cut differently than we did it.

[wiskey]

I've been searching for these rings and they are very hard to find. I believe they have been discontinued. Long shot but anyone have any they are looking to sell?

thanks.

[wiskey]

I've been searching for these rings and they are very hard to find. I believe they have been discontinued. Long shot but anyone have any they are looking to sell?

after a LONG search the ONLY place i was able to find a matching set of 4 rings(with 3 piece oil rings not 1 piece) was at bore-tech.com, although expensive at $27 a piston (almost the same cost as an ebay 836 kit that includes rings). Shipping was super fast got them the next day and they fit, so now on to honing out the cylinders!

here is the link for a reference http://bore-tech.com/product/350-piston-ring-set-65-mm
Should I just use stock clearances when checking ring gap?

thanks

[wiskey]

So im already to put these in. what piston to bore clearance should i have, also what end ring gap am I looking for? Should I go with what the manual states?