cylinders honed

[crazy steve]

First time I've seen the cylinders of these bikes.
Looks like there's "PLENTY" of room for boring - bigger pistons?

There's not as much meat there as you might think; the sleeves have a flange at the top, and that's what you're seeing.

And I think Wiseco also offers a 1196 kit (or at least did at one time), but that is the limit. To go bigger than that, you're talking custom sleeves and boring the cylinder/cases. $$$...

Pete, you might want to check your rings for up/down orientation; while the top ring and the oil ring have the same profile either way, the second ring doesn't. This one has a taper face, and which way the taper is 'pointed' can make a big difference...

These usually have a 'dot' on one side that's supposed to face towards the head.

[petejw]

hey steve,
i just checked the 2nd compression ring
and its the same as the top ring, theres no taper
or markings so they can be fitted either way,
i also checked the old original rings and there not
tapered or marked in any way, have you got rings
with a taper or markings on them?

also just to clarifer my cylinders are still in spec.

[crazy steve]

Pete, the FSM shows the rings in 'profile' and the top ring has a chamfer on both corners against the piston, while the second ring is tapered with sharp edges. The 'small' end of the ring taper goes up. I doubt if this taper is visible to the naked eye; you might be able to see it with a machinist square. Clymers doesn't have this info (but does note to 'install all rings with their markings facing up' which implies that there should be markings) but it's in the appendices section of the factory book. This is pretty typical to most engines.

The rings should be marked; now, how that's done can vary, but usually it's with a small dot on one side of the ring, but I've seen ink markings or lines too. Sometimes you really have to look to see 'em. If you wiped them down prior to installing, you may have wiped off the marks...

Why is this important? Some top rings can be flipped with no issues, but the second ring is also the 'scraper' ring. I've never seen a second ring that wasn't tapered (well, 2-strokes being an exception) because it's design is to remove excess oil from the cylinder walls on it's downward stroke and keep oil out of the combustion area. Put it in upside down, and it pushes oil into the combustion chamber; not a good thing.

You're using replacement rings, and they may be constructed different but I doubt it. If they're factory replacements, I would think that Yamaha would build them the same as the OEM ones.

[natemoen]

Ok, so I broke out the rings today and filed one piston worth. I will admit that there is an "N" very lightly stamped into the top side of the second ring and there is a "N25" stamped onto the 1st over rings that I have, so I am guessing that is the only markings on the rings and they are very light. have to have the light right to see thing marks.

[petejw]

steve, i agree with you if there are markings on the
rings they should be pointed towards the top (head)
but for the life of me i cant see anything on them,
any ring that ive seen have a taper/champher on was visable
and had some sort of marking, usually a dot.

tho in toms pic and as nate stated i now see n25 on the
top ring, id have that facing the top for what its worth,
my eye sight isnt what it used to be tho with a magnifying
glass i can just see n25 on the 2nd compression ring.

these arent yamaha rings but an aftermarket ring,
even sitting the top and bottom rings on top of each other
i cant see any taper.

maybe tom can chime in again with what way he put his rings in.

[petejw]

steve, have u got a copy of the bulletin
regarding the factory rings?

[crazy steve]

Here you go.....

[IMG][/IMG]

I'll note that this isn't to scale, and probably exaggerates the features.

[petejw]

thanx for that, that helps
but i still cant see a taper on either of these rings.

[crazy steve]

Pete, there several variations in ring designs, but one constant I've always ran into (at least within the last 20 years) is the top ring will have a chamfer on at least it's top edge. I'm not claiming I've seen every kind there is... just what I've seen. This chamfer can be very small, so you might need that magnifying glass...

If the top ring has only one chamfer, then the lower edge also acts as a 'scraper' so the second ring may or may not have the taper. Even when they are tapered, I don't recall it being something you could just see. Hopefully you don't have a mismatched set (all top or second rings instead of one each per piston), but you might check with the vendor if it's a non-Yamaha part to see if there is a difference. There's nearly always some way to tell the top and second rings apart, and all should be installed with any markings facing towards the head.

[petejw]

the top ring is thinner than the 2nd ring,
so theres no problems there, the 2nd ring
wont fit in the top groove, i sent off an email to the vendor
earlier asking if they know if the rings have a top
or bottom so ill wait and see if i get a response
from them.
mate, ive had that magnifying glass working overtime. lol

[cywelchjr]

That difference may be very very small, and that second ring being worn so that that taper is gone may explain those engines that inexplicably use oil having very good compression and clearly good seals with all the signs being of the oil usage being through the rings (generally thought to coincide with low compression). But if that taper is gone, that second ring could no longer be scraping the oil off the cylinder walls on the downstroke, leaving it to be pushed up into the combustion chamber and burned (not as bad as if the ring was good and upside down).

[TomB]

steve, i agree with you if there are markings on the
maybe tom can chime in again with what way he put his rings in.

Sorry Pete, missed this one Doh!


As you know we bought the ring sets from the same seller, mine didn't appear tapered either, I did the usual thing when fitting rings that you both mention, of putting markings upward. When fitting the rings in the bore for gapping any taper wasn't visible (I'm a time served Toolmaker who is anal as hell about this stuff LOL)

I know what Steve is saying about the 2nd ring being tapered but these aftermarket rings aren't. Also some aftermarket top rings used to come with different profiles and chamfers to account for the wear ridge in the top of the bore, dunno if this is the case with these rings. After honing the bores and removing any ridge as me and Pete have I don't see a problem.

My rings have done 300 miles now and the oil level hasn't moved at all, I'm pleased with them.

[petejw]

all good tom,
im satisfied that theres no taper on these rings,
the vendor got back to me and they had no idea.

[petejw]

finished doing the top end rebuild,
and have done the initial engine run in
and have about 400k's since of hard riding,
i used a straight 30 weight oil
changed it and the filter after the initial run in and used
the 30 weight oil again for the 1st 400k's,
now im running 20/50 weight oil,
the bike hasnt used any oil.

with regards to the oversize ebay piston rings,
i ended up using the old oil rails with out any
problem, other than filing down the ring gaps
the $45 rings were a bargain.

i also stuck a light in the plug hole and the pistons
are still polished.

overall really happy with how shes running.

[XS1100_OEM4ME]

Ridge reamer

thanx nate,
i ended up taking a bit of the the bores, i didnt want that
upper ridge left there.

hey davinci,
there off my original engine, theyve got
over 140,000k's on them, they cleaned up pretty well
considering, there was a fair bit of carbon on them.

I know it is after the fact, but before honneing, you should use a ridge reamer. It will remove only the ridge makeing it easyer to do the honneing. Then, a set of honeing stones with honeing oil with rapid in and out movement till low spots are removed. Then, and this is the most important step, finish off with honning balls with the same rapid in and out movement and oil to form a cross hatch pattern in the cylenders. All this removes the least amount of metal and the cross hatch makes for a faster break in and better seal. Your cyls look nice, not trying to undermind, just trying to be of help for others trying to do this work. I used to build pro-racing car motors, and the science is the same. You can rent all of the tools needed to do this if it is a one time thing, but they aren't expensive if you do it more then once or have friends the can benifit from them