Topic: Likely to need to hone or bore? Educated opinion sought

[trueblue]

I wouldn't go that far but .004"-.008" would seem reasonable for a used engine with miles on it. What I am saying is that is what is published in the Honda shop manual. I actually had one 812 bore job screwed up by the machine shop and it had .008" and it ran for several years until crashed to bits.

At 8 thou those pistons would have been slapping something fierce, most people just don't realise how big 1 thou actually is in machining speak, on an average car engine with a 3.5" cast piston you normally have 2 thou clearance on a new engine and they are worn out at 4 thou, with a forged piston the clearances are usually slightly larger because there is more metal in the crown of a forged piston and they grow a little more as they heat up.  To put it in perspective 10  thou is .25mm oversize and requires new pistons.

[Grey]

You'd be surprised at the maximum clearance between the piston and cylinder wa11. New minimum is around or just under .002" with limitations of about .012"

2.394" piston minimum dimension.
2.406" cylinder maximum dimension.
cylinder out of round and taper is .002" maximum
ring gap is about .03" maximum

So you know how much it wore in 10,000 miles before clean up so after cleanup you have something to chew on for remaining lifespan.

I can't see how it could seal and have any kind of compression at .012" clearance let alone the noise. Or did you miss a "0"? This is what I looked up in one of the manuals. It either means they want it in spec or close to it. Or let them fall out.............

Look at max bore and and min piston dia. Shows .0022" difference.

[andrewk]

I've always been a fan of "clearances you can throw a cat through."

I run my engines as loose as I can-  So long as you can achieve ring seal and maintain oil pressure, it will run better.

Of course there are limits to this, all I'm saying is that engine overhauls can be done "right" without over-boring, and without having the pistons knocking around.

[KC3]

It seems like some people want new or fresh rebuild specs these days when in fact half worn out engine parts still have lots of riding life in them

Ride it 'tll the wheels fall off! That's what I'm talkin about buddy! I love working on stuff, but I also love riding.

[754]

 You could always change the sleeve, and probably stay stock...

[lrutt]

overboring for an 836 kit will cost a fair penny as the machine shop has to take several steps to get it to that size. Just going first over will take a LOT less time. Just an FYI.

[Xnavylfr]

If you are considering boring to an 836 kit contact

www.cycleonemanufacturing.com

They do quality work and have a quick turn around time. There are very few others us chopper guys will even consider doing engine boring for us.
One of our group bought that CHEAP 836 kit from ebay and we installed it in his bike. It runs great without any poblems!!!


Xnavylfr((chuck)

[lucky]

Bore that out. (You'll be happy you did it right later). I reluctantly honed one about 10 years ago that looked about the same and long story short it ended up two cylinders down after a 2000 mile ride. Hole burnt thru piston #4 and "missing" chunk took out #3 later on...

Before ANYTHING happens the cylinders should all be measured top and bottom the correct way. Then make the decision to bore or just hone.

[KC3]

Bore that out. (You'll be happy you did it right later). I reluctantly honed one about 10 years ago that looked about the same and long story short it ended up two cylinders down after a 2000 mile ride. Hole burnt thru piston #4 and "missing" chunk took out #3 later on...

Before ANYTHING happens the cylinders should all be measured top and bottom the correct way. Then make the decision to bore or just hone.

+1 lucky--- ALWAYS do that first --  Check your specs -- Haste makes waste!

[Blasbo]

I was at the same point a few weeks back and did what rotortiller suggests.

Hone it, inspect the surface for corrosion pitting, check the dimensions both on cylinder and piston and if it passes install new rings and ride. 

After I honed it, I could still see some pitting and decided to get the cheap 836 kit. It works out to be cheaper than rings and a head gasket (not including the cost of boring). I asked a hot rod guy at work about a machine shop and he gave me a solid recommendation. I took the head up to him and he quoted $40 cylinder.