Show me your engine removal methods.

[Yard Dogg]

Thanks, I just can't afford to be throwing good money at everything I find, LOL.

[fredintoon]

- - - My motor was seized when I got it, and I have to fix the gears anyway, so I'm going to tear the whole motor apart. Question is, If I lightly hone my cylinders, do you think I would NEED to replace the rings? The bike actually runs fine and doesn't smoke. - - -

Hi Dogg,
if it was seized when you got it how do you know how well it used to run and if it ain't torn down yet how do you know what's wrong with it's innards now?
If the pistons, bores and rings look OK check the piston to bore clearances top, bottom and center with feeler gauges.
Push the rings back in and check the ring gaps.
Check the numbers you get against the maximum clearance numbers you should have.
If nothing's worn out of spec, the existing rings and honed bores should be OK.

[Yard Dogg]

I just came back in from pulling my head off. The cylinder walls look pretty good. It does show a little where the rings were froze, but there is no pitting. I don't know why, but these pistons look too small for these cylinders. Typically, I don't like to see the rings when the piston is installed. Is that typical of these bikes? There's probably 1/16 inch of play between the pistons and cylinders.

[fredintoon]

I just came back in from pulling my head off. The cylinder walls look pretty good. It does show a little where the rings were froze, but there is no pitting. I don't know why, but these pistons look too small for these cylinders. Typically, I don't like to see the rings when the piston is installed. Is that typical of these bikes? There's probably 1/16 inch of play between the pistons and cylinders.

Hi Dogg,
truly 0.0625" piston to cylinder gap?
Any more than 0.005" is plain worn out.
Either your engine is in serious trouble or you've been smoking those herbal cigarettes again.

[CaptonZap]

When checking piston clearance, the clearance is measured on the skirt, cross ways, (90 deg) from the pin.
The ring land area is smaller than the skirt, two reasons being that the top of the piston is subjected to more heat than the skirt, and thus subject to higher thermal expansion, and the gasses used to press the rings down and out have an easier rout through a wider gap. The wider clearance also keeps carbon from building up around the top and causing scoring.
So, without measuring the skirt clearance, you will not know if the pistons are usable or not.
If the skirt clearance is acceptable, the next measurement is side clearance of the lands. Tapered/ to much clearance here can lead to ring/land breakage, which is not good for other internal comonents
A good manual will give you values for these measurments.
CZ

[Yard Dogg]

Yeah zap, my eyes were messing with me for a second. I know the skirts are usually wider, but the pistons looked a little lopsided for a moment to me. I shined a flashlight in there and the gap is even all around. Looks great in there. I'm sure this motor is pretty stinking nice after all.

[BA80]

If it ain't broke don't fix it...................

[CaptonZap]

If it ain't broke don't fix it...................

Amen!
Take a plastic (Plexiglass) scraper, scrape the carbon off the tops, Take a piece of plastic milk jug and cut a hooked end piece to fish the carbon chunks out of the gap between the piston top and wall, take a vacuum and suck anything that will come out, put a little oil in the gap, and call it good.



RE hot tanks. There are a number of chemical types for hot tanks. The one for steel parts is an alkaline base, and will corrode aluminum parts, and dissolve them if they are left in there long enough.
The one for aluminum is a mild alkaline base, with buffers that keep it from being too caustic for the aluminum. It is subject to misuse, and will do irreparable harm to parts if not employed correctly. It is still capable of discoloring aluminum surfaces and pitting the metal.
Transmission repair shops will have the aluminum compatible type of wash machine, and might throw your parts in with their next batch.
I have used a five gallon tin bucket filled with water and Tide, heated over the BBQ, to clean parts. Be sure to rinse them thoroughly when done. Tide does have some alkaline chemicals in it, so watch the action, and remove when the dirt is softened enough to be blasted off with a hose, or brushed off with a stiff bristle brush.
Zep purple cleaner has also been useful, if the deposits have not been baked on. It too, is alkaline. Use as directed, and remember, there is no substitue for elbow grease.
YMMV.
CZ

[Yard Dogg]

hot water and tide huh? I've never heard that one. Good tip about the transmission shops, I didn't even think of that. I will probably start making some phone calls to them on monday. This time around I want to do it the easy way. If I had the tools that professional shops have, I'd do it all myself. From reading around it sounds like a real science getting aluminum clean enough to make paint stay on. I want to have them dipped, then I'll etch them myself. I'm still researching good coatings and trying to find some type of anodizing I can spray on. I had found some stuff a long time ago that was more or less like wood stain for metal, but can't seem to bring it up in search anymore. Seems like it'd get pretty spendy having to buy a bunch of solvent to anodize, then trying to somehow keep it off the internal parts too.

Got the valves and jug off today. I'm glad I'm tearing it all down now. The pistons show little to no wear, cylinders need honed, exhaust valves need lapped. There is a lot of gunk from sitting. It's gonna be a great motor.

[crazy steve]

I'm still researching good coatings and trying to find some type of anodizing I can spray on..

Anodizing is an electro-chemical process. While easier to do at home compared to plating, it's still not low-buck.... http://www.focuser.com/anodize.html

Anodizing also doesn't work all that well on castings either, particularly the 'scrap-metal' aluminum the Japanese are fond of. Cheapest really durable finish will be powdercoat....

[Yard Dogg]

Powder coating would be nice.

[natemoen]

Radiator shops should have tanks for both steel and aluminum cause radiators are made from either of those materials quite frequently.

[CaptonZap]

Painting aluminum is a rather finicky operation. And, as Steve mentioned, cast is worse than most, due to the porosity of the metal.
However, you can get some adequate results by being careful with surface prep, and primer application.
First, a good wash in HOT Tide /water, followed by a rinse in HOT distilled water, followed by a self etching zinc oxide primer, followed by a suitable paint. And, be aware that the thicker the paint film, the worse the heat transfer.
Here is a start on materials.

http://pc.dupont.com/dpc/en/US/html/...24_A-411XS.pdf

Dupont is quality stuff

A cheaper, and who knows if less desirable alternative;

http://www.walmart.com/search/search...l3=11666241816

In painting, as in a lot of other aspects of working on motorcycles, cleanliness is next to godliness, so be godlike in your painting endeavors.

CZ

[CaptonZap]

While posting the previous message, I could not think of the name of the stuff we used when doing aluminum parts. But last night, it came to me, in a dream, so to speak.

Alodine

Use a Bing search, and get the scoop on it. It is a chromate conversion coating for aluminum, and all the aircraft boys use it, as well as marine guys.
It is a little more involved than the self etching primers, what with surface prep and such, but gives better results. Works on cast, although some cast alloys are better recipients than others. And we don't know what casting alloy Yamaha used. Or do we?
CZ

[crazy steve]

...And we don't know what casting alloy Yamaha used. Or do we?
CZ

My best guess would be that it's not so much the 'alloy' that they used but how 'clean' it was. From polishing various parts, some polish up with little problem while others have contamination or even voids in the castings. Brake parts, the rear footpeg/muffler mounts, and fork sliders seem to have the fewest issues, the wheels seem to be good (surprising given that these are sand-cast), but these are highly stressed parts where strength is needed. The cast grab rails of the late Specials and XJ also appear 'clean', but that may be Yamaha's recognition that these parts get a better polish than the rest and any flaws in the casting would be too obvious.

The various engine covers and carb parts, I've run into casting flaws while polishing on nearly all of those to some degree. The hand control switch housings are the worst; I went through several 'sets' before I got one that didn't have very obvious flaws.

I'll also note that all these parts have the same 'color' when polished, with one exception. That exception is the bearing cover forward of the starter which ends up a bit 'bluer' than the rest. This part also appears to be forged rather than cast, so that may be part of the reason although a different alloy may be needed for the forging process.

To be honest, I'd be very hesitant to chemically strip the engine cases to bare metal, for several reasons. One, Yamaha did a very good job of bonding the OEM paint to the metal and getting a new-paint-to-old-paint bond if the old paint is still decent is much easier than starting from scratch. Two, Yamaha (and many other manufacturers) apply the paint to the unmachined castings (even the inside, unseen parts) and that acts as a 'sealer' keeping the casting from 'shedding' contaminates, preventing corrosion and aiding oil drainback. They then do the machining, only exposing bare metal where needed. The masking needed to duplicate this would be difficult to say the least, not to mention that paint prep/application would have to be excellent so the paint doesn't come off and clog passages. On the cylinders this isn't as much of an issue, maybe on the head.

Not saying it can't be done, but it won't be easy.....