Topic: Opinions about these pistons?

[super pasty white guy]

My '76 750F has a head gasket oil leak that's getting severe enough that oil is blowing back on my pants.  Not a gusher, but a pretty good weep.  I figure that if I'm going to take the time to pull the thing out to replace a gasket, I might as well freshen things up.  Not interested in going the 836 hotrod route.

Anyway, I've been looking around for parts and what I need/want to do.  I may wind up needing to go with oversize pistons and found these repros.  Anyone have an opinion or experience with these?

http://www.cmsnl.com/products/piston-025-repro_06132371000p/

spwg

[speedy gonzalais]

are you reboring the cylinders?

[super pasty white guy]

Don't know yet, probably.

I'm pretty green at this so I've got some more research to do.  Just trying to find out what's out there and have a good idea about what I'm gonna need before cracking the thing open.  Figure I'll buy the stuff I know I'll need before I start, then get the rest when I find out the condition inside.

spwg

[Clyde]

The pistons look good and are a reasonable price.
As they do not have the raised section as used by the 75/76F, they will have a slightly lower compression ratio . This is not really a big thing as the difference is only 9.2 vs 9.0.
They also have the 3-piece oil ring which is better than the single piece oil ring type.

[speedy gonzalais]

its best to take a look inside first, also if the pistons are over sized then a re-bore is required.

[bunghole]

Not to turn this in a parts for sale hijack, but I have my stock pistons if anyone wants them.  They were within spec when I tore the engine down to go to 836.

If you pay for shipping, I'll get them to you and then you can pay me what you think they're worth.  And if you think they're worth nothing, that's cool too.

[Jerry Rxman Griffin aka MuthaF'er]

If you have to spend your money on a rebore and a piston kit why not do a 836 rebore and not a 1st over??

[super pasty white guy]

Disclaimer-  I'm an engine neophyte, please correct me if I'm wrong.

It's my understanding that just from the mileage I may be looking at cylinders that are worn enough that they'll need to go oversize (I've put over 20k on since owning it).
I'd like to avoid both the retuning that seems everyone goes through with an 836 and the slippery slope that I know I'll partake in (well, if i'm going 836, I should port to get the best out of it, new cam, etc).

What is the chances that I only need new rings and a light hone?

spwg

[Jerry Rxman Griffin aka MuthaF'er]

Only way to know is to measure. It is very possible to just hone and re-ring. Did you mention mileage? Have you been running the crap outta it like some of us do? I've put 20K+ HARD miles on my 810 kit and it uses no oil BUT like yours it blows oil on my pants (I don't consider that using oil). I have honed and installed new rings. Yes, my head gasket has a slight leak but I really think the blowing oil is coming from the o-ring pucks under the cam towers.

[super pasty white guy]

Unfortunately, I don't know the mileage.  The clocks weren't original when I got the bike.
I'm not burning oil, at least in a substantial amount.  Compression is in the 120-130 range across cylinders (2 at ~125, 1 at ~120 1 at ~130).

spwg

[Clyde]

Honda cylinders are very good and tend to last a long time.
You will only know for sure when you pull the engine down, but therer is a good chance a light hone to remove any glaze and a new set of rings will give the engine a new lease of life.
At the same time you should do the valve seats as they can also make a difference.