Cleaning pistons and Valves

[tarzan]

If everything looks ok You should be fine.Its hard to tell from the pics but it looks like the cylinders dont have much wear,is that the case?I would lightly hone the cylinders and put it back together.

[kirmit77]

everything looks pretty good and i did plan on honing it just enough. ill take some more detail pics of the cylinders but to me they look good. no scarring or scratches just the top is really dirty

[trbig]

Wow...

Sorry I missed that.

Throw a very light hone onto the cylinders and throw it back together if you think that's the true mileage. You won't need rings.. unless that's 109,800. If the valves are as nasty as you say though.. that may be more correct. I can't see them getting too jacked up in 10k miles, no matter how rich it was running.


Tod

[kirmit77]

well....

its been sitting since 1985 and i know the full story and the owner and that is the exact miles. ill try doing a light hone on sunday and slapping it all back together! hope to get it running soon but cant find anyone around here that has a friggin C-clamp style valve spring compressor..... o well ill keep lookin.

[kirmit77]

what is everyones take on this ???

What does everyone think about these Viton valve seals??

i just need the seals and then i can get to gettin on the rebuild

http://cgi.ebay.com/ebaymotors/YAMAH...3A1|240%3A1318

[trbig]

You can ease the top ring off of the pistons and slip them down into the cylinders so they are sitting just like if they were on the piston (Horizontally). You then take some feeler gauges to check the gap between the ends of the ring. Standard gap is .2-.4mm (.008-.016") with a limit of 1.0mm (0.039")

More than likely, if the top ones are ok, the rest will be also. Be careful getting the rings off though since they will be pretty brittle.


Tod

[TopCatGr58]

Hey Kirmit,

You can make your own with a regular C clamp, get some PVC pipe, cut a nice slot in it about 120 degrees worth, leaving enough space to have access to the keepers, but not so much of a gap that the pipe section would slip/tilt. Use the solid part of the "C" clamp on the valve heads, and use the screw end on the spring end with the pipe. Check out the tech tips for photos on this. Like it's been said, most have done just about everything before, just need to look or ask!
T.C.

PS, you haven't said, but hopefully you're going to LAP your valves once you've cleaned the hard carbon off of them!?

[kirmit77]

next questoin

What is the procedure on lapping?

[TopCatGr58]

You get a fancy little double suction cup wooden device (Lapping Tool), and a tube of lapping compound, put a nice thin layer of compound around/onto the sealing surface of the valve, slide it into the head, and then use the suction cup to grap the valve head, and spin and press slightly against the valve/seat to GRIND the mating surface of the valve and seat. When done correctly, you then see a nice little gray line on the valve and seat, about 1/16" wide or so. When it's complete, no spots, gaps in the line, then you're done, clean the valve and seat thoroughly...you don't want that gritty compound getting into the rest of the engine.

This is the poor mans way of reconditioning the valve sealing surface instead of having the head and valves reground by a machine shop!
T.C.

[kirmit77]

sounds good

ill will be definitely do it. BUT... i need to know about the valve seals i have posted up a couple of post. any recommendations???

[TopCatGr58]

That's a good price, and they seem to be quality stuff. I paid $8.00 EA in 2000 for a set from YAMAHA since I didn't know better back then. You can get a complete gasket set for $80.00 from Partsnmore.com, and it comes with a set of valve seals also! What were you going to do about the head gasket?? OEM from Yamaha is also $80.00, you get that one in the kit also!
T.C.

PS, just checked PNM, they have the individual valve seals for $2.00 ea!!!! I think MikesXS carries the lapping tool, but you can get that from your local auto store, even Walmart I think?

[petejw]

hey Austin,
You can see if the valves are leaking by placing the head on its side and pouring petrol into each port, if theres no seeping/leaking your head's good to go, do this 4 both exhaust and intake valves.

[Ivan]

Valve seals are almost an afterthought. The old Chevy engines used to just use a small plastic "umbrella" that didn't even seal. It was merely a deflector. The tolerance on the valve guides is small enough that oil has a hard time getting passed there, and if it does, there is so little that you won't even notice it burning. The sign of leaking valve seals is a puff of blueish oil smoke on start up that goes away in a few seconds. Usually, on an automotive engine, something else will break before the leaking valve seals will cause a fouled plug.

All that is leading up to:

Valve seals are valve seals. Cheap ones work just as well as expensive ones. Viton isn't really necessary. They all work about the same.

[79XS11F]

I don't have my lens in so I have not read the whole threat but here's my input. On all three of the engines I have rebuilt I have cleaned the valves on course brass wire wheel on a beach mounted grinder. I use a hand held drill and wire wheel on the combustion chambers as well. Do it with the valves in place and avoid hitting the gasket surfaces.Tops of pistons were cleaned with a thick feeler gage followed by wire wheel. don't hit the sides of them so be careful. Combustion chambers were then buffed to a mirror like finish with a polish suitable for alloy. Once the valves and guides are cleaned with contact cleaner put the valves in place and check for any side play. There should be none with everything clean and dry. After the head is reassembled using assembly oil as necessary, in the turn it upside down on the bench and fill each combustion chamber with alcohol right to the gasket surface.Let it sit for several hours like that and see if any of the alcohol got past the valve seats. if so lap the valves of that cylinder and test again. If there is no leakage your good to go if all the springs were of correct length.
If theres no piston slap and the ring gaps were good you could reuse them but given that the engine is apart I would give the bores at least a quick light hone with a fine stone followed by using ether new stock size rings that have been gaped to spec or 1st. over size that have been gaped to spec. On the 1st. over size rings you would have a lot more filing to do to reduce them to the correct size but it can be done.
Rob

[Steptoe]

white metal

g,day kermit, if your that far down in the motor check how much [they call it ] white metal is left in your gudgeon pin hole top of conrod,[little end] check for slop with your old pin as well,you,ll have some wear[diagonal in the hole] as long as its not square to the rod,[up and down] .worst comes to worst they can be re-metaled. as for the carbon go to your local auto store and buy a decarbonizing brush that fits in the end of your drill