piston, ring, and rebuild?

XSiveAl · Posted: April 12, 2009, 1:33 pm Post subject: piston, ring, and rebuild?

Last update of Al's bike..

bike was running well,.. started on second kick.. looked good, sounded great... The clutch, although sticky pushing it,.. performed suprisingly well on the road. ran straight and true,.. shifted through all of it's gears,.. bogged down a little on wot. All in all.. it's all there

It would not stop smoking like a demon. I ran it for less than ten minutes and the plug ground straps were so black I wouldn't have expected it to run at all.

I thought it was likely frozen rings from sitting.. Neither penetrating oil or curse words could fix it. The outside of the motor is sooo clean and repainted by the PO.. I expected to find inside a fresh rebuild done plain wrong.

so i tore into it and wow is it ever easy. there's like ten moving parts? totally uncomplicated. took me six hours to get from complete bike to having the motor stripped to the cranckcase mouth.

I found what looked just like R.G.'s post of his coal burning cylinders in there.. lot's of carbon.. but really wet deposit too.

I didn't have to look too far... with the head gasket still in place i could see that it was physically contacting the pistons in both cylinders on the exhaust side and bulged up respectively.. and from each bulge wet cooked on filth trailed into the cylinders, and a little exhaust gas residue found at the other ends of these trails too.. also down the studs on the exhaust side. looks like the gasket was either too big, deformed or the wrong part. It's black and just like pics of the stock ones I've seen so I think it's a yamaha part.. wierd eh? anyone ever see this happen before? how can somethng like this be avoided?

below that I found that the cylinder walls are glazed.. shiny and no evidence of scuffing or seating.. ring gaps are well within spec. Rings are shiny clean.. and totally free floating. no carbon in grooves and no corrosion or discoloration from heat.. the pistons, after I cleaned the carbon off are almost totally unmarked.. with only barely visible scuffing on the skirts.

the number on the pistons is 963 so i think, tell me if i'm wrong please, that it's the first oversize, meaning 74.963? and also.. unmarked top ring goes dullest side up? they have no beveled edge in or out.

i figure the PO rebuilt or had it bebuilt,.. rode less than 100 miles.. leaking oil prevented the rings from seating, (likely noone retorqued the head either.. I found some of the dome nuts to be at less than 15ft/lbs) and they probably parked the thing and walked away frustrated.. kicking things and yelling "all that money and time and it's still a POS!!"
Then i come along, ten years later, and think i can probably just hone the cylinder's lightly, install new piston clips ( a given), new base and head gaskets PROPERLY.. lap valves lightly, install new valve seals, since I'm in there, and ride away a fresh rebuild?

I've got no play in my piston pins, my head holds solvent in it upside down overnight.. no leaks... and my cam chain is very tight with lots of adjuster left.. I removed it without breaking it by sliding off the bearings after removing the tensioner assmb'y. even the cam tensioner and guide bar have lots of life left..

I was going to order every part from the piston pins up but, do you very experienced persons think I should try to put it together on the cheap and easy first.. and then re-ring later when/if necessary?

many thanks
- Al

yamaman · Posted: April 12, 2009, 2:12 pm Post subject: Re: piston, ring, and rebuild?

What were the oil ring gaps, they seem to be the fastest wearers?

963 is a standard piston, 74.963mm, first oversize is 75.25mm
If the bores, pistons & rings are in spec, then new ones wont be any more in spec!

Could be a cheap rebuild, gotta love that!

Retiredgentleman · Posted: April 12, 2009, 3:44 pm Post subject: Re: piston, ring, and rebuild?

XSiveAL;
If you have read my thread on "top-end rebuild", you know I've seen first hand what poor torquing procedures can do to an engine. Several other chaps have reported the same thing. Too many guys putting these motors together without the knowledge to do it right.

The "leakless assembly" thread over at 650garage is a must read for us guys putting these motors back together. I just got my engine back running 3 days ago, and so far (only 120 kms) the engine is running perfect. My last topend re-build was about 26 years ago, so I paid attention to advice from guys like 5twins, and grizld1.

I used 3 bond 1104 on the head gasket, around the camchain tunnel and the 4 outer studs exposed to oil. Just a gasket for the cylinder base. 3 bond 1104 for the rocker cover. Gasket surfaces must be super clean, wiping with lacquer thinner just before assembly.

Last but not least, pay attention to the torquing. Using 30 ft-lbs for the large 10 mm studs. 14 ft-lbs for the 8mm bolts. After the first engine running and cool down, several of the studs/bolts rotated. My head stay is still off, while I build up the kms and re-check the torque numbers.

I agree with yamaman, if parts are in spec, why not re-use them. Read the Yamaha service manual at sites such as www.biker.net or at glpool.com/xs650/. For the last site mentioned username=xs650, password=xs650

XSiveAl · Posted: April 15, 2009, 3:50 pm Post subject: Re: piston, ring, and rebuild?

Seems like sound reasoning for sure. Thanks guys.

I'll save my money for the next rebuild. I've ordered only the necessities from Mike's.. definitely a business worthy of support. I wonder about the change on the order sheets.. advertised as 3 bond 1104 changes to 3 bond 1194 on the form.. ? is this the same thing?

the laquer thinner for the wipe down?.. is that good for removing the stubborn gasket material as well? I've used carb cleaner in the past but, I understand it may leave a residue.

counting the days til my parts get here,
-AL

Retiredgentleman · Posted: April 15, 2009, 6:16 pm Post subject: Re: piston, ring, and rebuild?

3-bond 1104 is the correct stuff. 1194???

You need to have the gasket surfaces all cleaned up by whatever method you choose. The laquer thinner is just the very last thing, in order to remove any grease or oil film, which then allows the 3-bond to adhere to the surface.

xsjohn · Posted: April 15, 2009, 6:28 pm Post subject: Re: piston, ring, and rebuild?

Rich people bond their headgaskets...poor people use pam.......... Laughing

xsjohn

dwyatt · Posted: April 15, 2009, 8:18 pm Post subject: Re: piston, ring, and rebuild?

Rich people have staff to bond their gaskets.

xsjohn · Posted: April 15, 2009, 8:35 pm Post subject: Re: piston, ring, and rebuild?

Poor people have their bikes back together the next day because they need them........rich people work on them for months....... Laughing

xsjohn

XSiveAl · Posted: April 16, 2009, 12:53 am Post subject: Re: piston, ring, and rebuild?

PAM!.. I'm sure that musta been what the damned PO used to get that headgasket to slide around like it did .. Oh man,.. I sure wouldn't want to have to confess something like that to you guys.. so maybe I'll go in fer that 'spensive 3 bond stuff and pretend I'm rich folk, maybe have the help put it in..

I looked around for it the other day... up here in Canada like yourself RG
it's not at crappy tire just the form-a-gasket stuff.. Lordco maybe,.. I'll try all the auto parts dealers around here til I find some

I did order it so I'll see when it gets here.. from XS650direct.. the item description says 1104.. but the parts list in the confirmation lists it as 1194.. I hope it's one of those user interface kinda errors.

-Al

xsjohn · Posted: April 16, 2009, 7:42 am Post subject: Re: piston, ring, and rebuild?

Not recommending but Pam is what I use........have never bought a headgasket yet..... just collected a few.......haven't had one leak yet ....just reuse them with some prep... Laughing

If you bond the head gasket better read up........just a tiny bead with a toothpick or the head will be very difficult to get off............

xs650temp.proboards.com/index.cgi

xsjohn

XSiveAl · Posted: April 17, 2009, 10:13 am Post subject: Re: piston, ring, and rebuild?

XSJOHN,,

sounds interesting, really. no joke. I'm the kind of guy who saves everything and believes i can do it all at home with hand tools.

my head gasket's damaged so i can't reuse it at all. the metal rings around the cylinders are burned and broken. but maybe i can set up to salvage the next one.

would you kindly elaborate on your Pam trick? I remember i looked at the ingredients list once at my mother in law's... it sure isn't food...

-AL

xsjohn · Posted: April 17, 2009, 11:50 am Post subject: Re: piston, ring, and rebuild?

My statement was a bit misleading after I read it again......a used gasket is usually damaged around the center tunnel front and back from the seal on new gaskets.... .I did buy a new one like 9 years ago......and the first retorqing after the engine warms up is important I would think....top and bottom gaskets squish as soon as it gets hot.......especially the bottom barrel gasket......

And using Pam I read on some other boards...so I tried it...and one would have to believe it would increase the chance of leaks......so careful torquing would be essential....like 3 times at least......and I do push it to 35LBS....

Shoot I am now bonding two used ones together in the center building the center up a bit and using Pam on the outsides and not getting leaks.....not the first time I tried it though....

xsjohn

TheRepairMan · Posted: April 17, 2009, 4:28 pm Post subject: Re: piston, ring, and rebuild?

xsjohn wrote:

Poor people have their bikes back together the next day because they need them........rich people work on them for months....... Laughing

xsjohn

I must be really rich ...I'm still just planning to work on mine!

Cool

-R

XSiveAl · Posted: April 21, 2009, 2:05 am Post subject: Re: piston, ring, and rebuild?

xsjohn,

let me know how you make out with your new set. You're on to something there, I bet. Could really be worthwhile examining.

I found this on an XS1100 site:

"If you frequently disassemble parts while working on your engine, such as removing the cam cover for adjusting valve spacers or removing a carb float bowl, spraying PAM non-stick spray on the gaskets prevents them from sticking to metal surfaces. The gaskets won't tear during disassembly - allowing their re-use."

explains it well.

I think this is interesting. I like to reuse things. and take stuff apart,. but I would wonder, how do you keep it from leaking?
is it useful for applications involving high temperature and pressure as well as exposure to gasoline and oil vapours?
considering the damage i can do over-tighteneing things is it worth the risk?

and also, if it doesn't work, can i clean the pam off well enough to bond them instead?

It would be great if when it is time to tear into it again it doesn't cost the new gaskets.

I've used cork/rubber, cut by hand, available in rolls $15-20 /per. should work well with anything that doesn't involve too much heat and pressure. clutch cover gaskets, carb bowls, cam chain adjuster cover, gas tank seals, etc.

I don't think that it'd make a good head gasket, though. could it?

-Al

xsjohn · Posted: April 21, 2009, 3:02 am Post subject: Re: piston, ring, and rebuild?

XSiveAl...Would need the bit of metal for a head gasket I would think.....I've used pam for 8 years now........would think most everybodys leaks are from having never been torqued after the initial factory assembly......heck I am using 2 used head gaskets with some prep and geting away with it.......I usually tighten the 4 center acorns a couple LBS more....don't want the lower cylinder gasket to leak though.........kinda blows the day..........Heck I still use the ole Indian Head gasket sealer for the center cases........shellac.....easy clean up.........

replacement head gaskets are crap... I always try to use the original Yamaha ones when bonding together 2...they are way tougher than the wimpy replacements....bonding two used replacement gaskets together would be kin to using chunks of cardboard box..........

Beginning of last year when I started experimenting with 8-1 compression I bonded 2 used replacement gaskets together.......leaked like a sieve......didn't care though cause I figured I was going to have to lift the head again to change the cam......which I did.....found 2 originals and boiled them and built them up in the center (just the front and back) with a tiny layer of epoxy in the center before bonding them together.....then pamed the bitch.......fun to be on now......settles right down like a car....

xsjohn

XSiveAl · Posted: April 21, 2009, 6:12 pm Post subject: Re: piston, ring, and rebuild?

boiled them eh? just in water.. air dry?

I can't use the one out of the motor I'm rebuilding because of the damage to the metal rings, but I have two other parts motors.. a 76C and an 80SG .. neither running.. one i managed to break free from seizure but, haven't had it apart yet. the other was slightly cannibalized when i got it. the heads still together, though. Likely very soon I'll strip them down too. maybe a 750 project. I'll experiment with reusing the gaskets for sure if I find that they're in good shape. i wonder if cork/rubber would work as a base gasket?

I read through some of your posts about lowering the compression.. and balancing your crank,.. and the needles.. your bike must be the quietest, smoothest running example of an XS around.

my parts arrived today.. very exciting.. I ordered the athena gasket kit and I'm going to try them out this time. It won't be long now & I'll be off and running. maybe another week? maybe this weekend if i can find the time.

-Al

tacoswild · Posted: April 21, 2009, 8:17 pm Post subject: Re: piston, ring, and rebuild?

I can't find any standard size rings for mine (it's a 256 engine) but I think someone here mentioned using 1st over rings on standard pistons by filing the end gap or something? Anybody know about that?

xsjohn · Posted: April 21, 2009, 9:51 pm Post subject: Re: piston, ring, and rebuild?

5twins mentioned that a few times.............xsjohn

5twins · Full Member Joined: Aug 05, 2006 Posts: 1616

deleted

tacoswild · Posted: April 22, 2009, 2:12 am Post subject: Re: piston, ring, and rebuild?

Thanks 5twins I'm going with that then, just ordered the rings.

xsjohn · Posted: April 22, 2009, 7:34 am Post subject: Re: piston, ring, and rebuild?

Wouldn't it be something if all the rings ..std through 4th over were really the same ring except the end gap........??

xsjohn

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