Cleaning pistons and Valves

[kirmit77]

Hello everyone, I am needing to know what would the best way to clean some pretty nasty valves and the tops of the pistons. Also, what ring size should i get for when i re-install?

[dbeardslee]

Kermit - That carbonized stuff gets pretty attached to the back of the valves and stems. I used paint stripper and elbow grease. I had one of those el-cheapo wrenches they give you in a bag with nuts and bolts when you buy things that require assembly - relatively soft metal, but hard enough to scrape the deposits off. The top of my cylinders I cleaned with a wire brush, but somebody will probably scream bloody murder about that . Be careful NOT to clean the little carbon ring around the top of the cylinder - some say it can cause overheating.

[BigDick]

couldn't resist

the top of my cylinders i cleaned with a wire brush, but somebody will probably scream bloody murder about that :d.

bloody murder! ! ! ! !

[kjohnson]

You could pretend to be a good SO and clean the oven and while you are at it spray the parts and put them in there too. Oven cleaner is great for de-carbonization. don't know how bad it is for the aluminum tho.

[dbeardslee]

BigDick - LOL

[randy]

Oven cleaner is not kind to aluminum. Try it on aluminum foil. The foil evaporates.

[trbig]

Use a wire brush for the valves, but not on the aluminum pistons. I found a small-ish plastic tub with a lid, poured a couple inches of Berryman's into it and stuck the pistons in there upside down, put the lid on to keep it from evaporating, and left it a couple days. It softened it up to be able to get the majority of it off.

Don't worry about removing the carbon ring at the top of the cylinder.. (Meaning that it's fine to remove that). It will have to be gone to hone the cylinders anyway.

The standard bore for the cylinders is 71.5mm. It has a wear limit of 71.6mm. I have heard of people having problems finding the standard size rings, so you may have to get the first oversized (71.75mm rings) and gently file the ends until you get the proper gap. It would be a PITA to do all of them though. If you are out of tolerance, you may consider doing a big bore on it.

Tod

[fredintoon]

Hello everyone, I am needing to know what would the best way to clean some pretty nasty valves and the tops of the pistons. Also, what ring size should i get for when i re-install?

Hi Austin,
if the valves are that nasty they need to come out so you can get the valve seats re-cut.
Spin the valves in your drill press and use the rounded end of a hacksaw blade as a turning tool to get the worst of the crud off.
Finish off with emery tape held against the valve with your finger tip.
Um, depends on which oversize your pistons are, don't it?

[TopCatGr58]

Hey Kirmit,

Sorry you felt like you had to tear into the head and pistons. Have you removed the jugs already?? You can get the jugs micrometered to check for out of roundness and wear limit. I think you said you had found some RUST inside the cylinder???

As was stated, the 1st oversize rings are probably what you will need to get, so you can do a HONING if the jugs are within limits. However, the ring sets are not cheap, like $40.00 a set....that's per piston!! A little big bore kit is about $400-500 depending on where you shop. It has NEW pistons, rings, wrist pins, keepers, and the oversized head gasket. You would still have the extra expense of having the jugs bored.

The problem with YAMAHA is that they quit supporting the XS11 after about 10 years after production, so 1st, 2nd, any oversized stock pistons are Unobtanium!!!! So...if your jugs are beyond wear limits, you're looking at a big bore kit of some kind. HTH!?

I've also heard of folks using some VINEGAR soaked wrags to lay on the pistons carbon to decarbonize them. It's a mild acid that works well. YMMV.
T.C.

[kirmit77]

Hey Kirmit,

Sorry you felt like you had to tear into the head and pistons. Have you removed the jugs already?? You can get the jugs micrometered to check for out of roundness and wear limit. I think you said you had found some RUST inside the cylinder???

After sitting for so many years, EVERYTHING needs to be torn into.... in my opinion. Ill take some pictures and put them up here of everything.

[kirmit77]

Pics

Here are some pictures i took. The cylinder walls look ok, no scratches and the rings are all intact.














.

[BigDick]

BigDick - LOL

Yeah, my screw comes loose once in a while. Especially at work when I'm either bored out of my mind, or about half asleep, or wired on coffee, or any combination of those three.

[trbig]

Hmmm.. I haven't seen anything I personally would have torn it apart for. The head off maybe... to see why they quit riding it... but that carbon on the pistons isn't that bad. Maybe burning a little oil through the seals or running a bit rich.

You never did say how many miles were on the bike.


Tod


Ohhhh.... Scraping that base gasket is my FAVORITE part............ NOT!!!

[kirmit77]

9800

If you go look at my 79 Revival thread you will see that i said it had 9800 miles on it. Im doing this all because of precautions.... and its fun!

[kirmit77]

okay another question

It seems lik the rings look fine. Im going to mic everything and double check. If everything is good, do you think i could use the same piston rings??

Thanks