Engine rebuild

[IanDMacDonald]

I purchased the Emgo set off eBay, but purchased the base gasket as an NOS Yamaha part. It's a thicker material. Some guys will go without, and to each his own.

I'll use some of the gaskets in-conjection with RTV (ACCT). The valve cover I spray with PAM so that it won't stick. Everything else I use on its own.

[TopCatGr58]

Well,

After having failures with black RTV, I changed to ThreeBond/Yamabond, the grey stuff. Have used it for ALL of the engine gasket replacements, even the top valve cover, no drips, runs, errors! The only gasket I have on the bike now is the HEAD GASKET, and the timing cover because it's just a dust seal, helps to keep the bolts locked/secure. I made that one out of gasket material, an exacto knife and a single hole punch. Just a suggestion, YMMV.

T.C.

[e30 gangsta]

Wow that's impressive. So no base gasket? Just the orings and some yamabond?

[TopCatGr58]

Okay, let me clarify that. I DID use a base gasket with my original rebuild/big bore in 2000. Other's have just used the O-rings and sealant, have said that it may increase the compression a little with a thinner/no base gasket vs. one. When I did my 2nd tear down tranny fix and such, I didn't pull the jugs off, but almost every other cover, tranny pan, clutch, valve cover, cam chain tensioner.

T.C.

[e30 gangsta]

Alright guys gasket kit, big bore pistons kit, acct, and new intakes have been ordered.

I have some questions about the head. The bike has 10k miles on it and ran fine until cyl #2 started to show low compression. Do you guys think its worth sending out the head to get rebuilt? The only thing that worries me is the valve seals since they're so old. Do you think I could get away with just running the head as is? Also another reason I want to run the head as is I wouldnt have to worry about checking the clearance on the shims.

Thoughts guys?


Schumann Motor Works sent me this reply after I messaged them about a head rebuild for the xs.

Hello, thank you for inquiring. I do have a complete rebuild service for $490.00 which includes tear down, clean, bead blast ports and chambers, new bronze valve guides, complete valve job, lap deck surface, and assemble with new viton seals. I can't do cylinder boring here but can definitely evaluate and do a glaze break hone it it's in spec.

[bikerphil]

I would change the valve seals for sure. Only 10k I would think the head would be fine. I have one with over 150k on it and have only changed the seals. I would check the valves for leaks by placing the head upside down and with the spark plugs installed, pour fuel in the combustion chambers and let it sit for an hour. There should be no fuel leaking past the valves.

[IanDMacDonald]

How much disposable money do you have? Lol. If you have the valves out for the seals to be replaced, have the valves back-cut, seats re-surfaced, lash set, and ur good to go!

[skids]

How much disposable money do you have? Lol. If you have the valves out for the seals to be replaced, have the valves back-cut, seats re-surfaced, lash set, and ur good to go!

Valve grinding compound can recondition the valves and seats nicely.

[e30 gangsta]

I would change the valve seals for sure. Only 10k I would think the head would be fine. I have one with over 150k on it and have only changed the seals. I would check the valves for leaks by placing the head upside down and with the spark plugs installed, pour fuel in the combustion chambers and let it sit for an hour. There should be no fuel leaking past the valves.

Thanks for the tip! Ill try that tonight, if I don't find any leaks Ill just have the machine shop swap out the valve seals for me. Or I might do them myself if I can rent the tool. Thanks for the tip!

[bikerphil]

You don't need a special valve compressor, a 6" C clamp with a short piece of PVC with a slot cut in it to access the keepers works fine.

[e30 gangsta]

Thanks for the tip! Alright guys so good news, I flipped my cylinder head over poured some water into the chambers overnight, let it sit and theres no leaks! Guess the valves are sealing good so I'm just going to swap out the valve seals!

As far as the carbon buildup on the head do you guys have any suggestions on how to go about removing all that black buildup?

Also the 1196 big bore kit showed up!!! Gonna drop off the rings/pistons and barrels at the machine shop and just have them set them up for me. Figured that would be the easiest.

I wanted to know what you guys recommend for piston ring gap on this engine so that I can be clear on what I need done.

Thanks again for everyones help!

[TopCatGr58]

Glad to hear there's no leaks, however, I would still at least LAP the valves since you'll be taking the springs off to replace the seals, you can get the lapping compound and tool quite cheaply. Just be sure to clean off the compound afterwards. This will ensure a good sealing surface between the valves and seats that could have both corrosion, carbon, rust, etc. there!?

I've heard folks have good luck with some rags soaked in vinegar letting them sit/soak on the carbon a while and then wipe off. Others will use some BRASS wire brushes/cup brushes on drill to GENTLY scrub it off, YMMV.

Don't forget to put some OIL on the seals before putting them on/in the head.
Forgot, I would think the ring end gap would be the same as for the stock engine, it's in the manual!

T.C.

[DiverRay]

I've used Berryman's B12 Chemtool for cleaning carbon on a few engines. Put a little on, let it set and wipe carbon off. PLASTIC scraper works well to get it off, as it will not dig into the head like a steel blade scraper will.
I pulled the valves and cleaned them by checking in the drill press and using some steel wool then fine emery cloth to polish the transition between the valve head and the stem. Then lightly oil the valve before putting it back in, after lapping it.

[skids]

Glad to hear there's no leaks, however, I would still at least LAP the valves since you'll be taking the springs off to replace the seals, you can get the lapping compound and tool quite cheaply.

T.C.

Lapping the valves is really pretty easy. It may change the shim clearances a little - don't overdo it! It will be easy to examine to sealing areas: valve and seat. Look for pitting. I have to say, if the valves do not leak liquid overnight, they seem pretty good to me! I would be reluctant to mess with them, but that's just me.

[mack]

Head

Lapping is a good idea. You can tell by the position of the polished portion on the valve as your lapping what the condition of your seats are. To remove the carbon deposits I use paint stripper (circa 1845 or something like that) If you strip the head down, don’t be afraid to power wash it. You can’t hurt anything. Then use a gun cleaning kit to run the oil galleries clean. You’ll be amazed at what comes out of them. And make sure you save all the thin washers under the springs. Measure your spring length and replace as required.