Noob engine help

[skids]

Tie that in with associated statements referring the guide seals so assumed,obviously the valve guide seals would be replaced.....pretty simple.....'taint rocket science.

Guide seals, OK, the other is unrelated fluff that has nothing to do with oil consumption. Valve lapping would be a good idea to do it while doing all of the other work, but has NOTHING to do with oils consumption. I ain't no rocket-surgeon.

[AggiesaurusRex]

I think somebody missed their chicken pox vaccinations. Thoughts?

[motoman]

Definitely an oil fouled carboned-up fuster-cluck.

[3Phase]

Well, it swallowed something and got indigestion.

I can't think of anything in the stock intake tract that could do that except a throttle plate screw. Are both of the throttle plate screws still in place in the carburetor or does one look like it's been replaced?

[AggiesaurusRex]

They are all the same screw so as far as I can tell they haven't been messed with. Should I be worried about the craters or as long as it didn't sneak under and damage the valve seats its something I can just light sand out?

[3Phase]

You don't have to screw with the carbs so that's a good thing!

You can use a ball peen hammer and a metal rod to work some of the divots back down in the cylinder head before you smooth them out so you don't lose material in the combustion chamber.

The same trick will work for the top of the piston too but you have to be careful, hammering on it with no oil pressure can mess up the holes for the wrist pin and smoosh the rod bearing.

If it was me I'd just get another piston and a non-FUBAR cylinder head. De-glaze the jugs, re-ring, lap the valves, put in new valve seals and be done with it. A new cam chain while the head's off would be good too.

[AggiesaurusRex]

I finally removed the valves and had a look at the seats and what was hiding underneath. I have a crack in two of the exhaust valves, not quite reaching the seat of the valves, and a crack in one of the seats on the cylinder head. Is that something that can be repaired by cutting new seats or is it kuputs? I've found brand new valves, so I'm not so much worried about them as much as the head.

[AggiesaurusRex]

[Bonz]

I don't see anything I would call a crack in the seat in the head, I see some surface erosion or surface pittting. Any chance or any way do you know if that coincides with the area on one of the valves?

I haven't done a valve job myself on the XS1100 however I would suspect the standard three angle job would clean that up. If you don't want to do that take one of the old valves and lap the valve seat to smooth it out. Smooth the seats in the head and smooth out the seats on the "new" valves, should be a pretty good fix in my estimation. Also put in new valve guide seals or check they are not leaking.

What I understand one cause to be, the valve stem seal lets oil run down and it cooks on the valve while it's hot when the engine is shut down then over time bangs between the valve and seat. Effectively tightens up your clearance and then gets hot which makes it want to pit even more. Does that ring true in anyone else's mind? Looks like there is some carbon on the stem above the valve head. Was there a good amount of carbon on the backside of the valves that you already cleaned off, or is this how they came out of the engine? Could also be running premium gasoline and carboning up the valves that way too.

[3Phase]

"It's dead, Jim!"

Forum Member Andreas Weiss usually has parts, send him a Private Message:
Andreas Weiss

xs1100 parts for sale-summary-andreas


You can find complete engines and even complete bikes but here are a couple of eBay listings for the parts you need:-


US $74.95 + $22.79 Standard Shipping

80 YAMAHA XS1100 XS 1100 MIDNIGHT SPECIAL OEM ENGINE MOTOR CYLINDER HEAD




US $150.00 + $20 expedited shipping:-

Yamaha 1100 XS SPECIAL XS1100 Used Engine Cylinder Head 1980 YB139





US $65.95 + $15.50 Standard Shipping

80 YAMAHA XS1100 XS 110 LG MIDNIGHT SPECIAL OEM PISTONS WITH RINGS X 4




You're in Orlando, FL? Here's a complete bike and engine:-
US $550.00 Local Pick-up Only | Mount Pocono, Pennsylvania

Yamaha XS1100 midnight special (low miles 4,165) motorcycle sold as parts

[AggiesaurusRex]

If you scroll up Bonz you can see a picture of all the carbon, none of the valves could close fully because of the carbon. It was thick and everywhere. The last picture is after hours of cleaning. Also in one of the pictures there's a definitive chunk out of one of the seats. Just click on it and it gets bigger for better viewing, I know its small in the page. It and the matching valve both have damage.

3Phase, I did check eBay and those exact posts prior to making this post, but the heads either don't have clear enough picture or the valves look worse than mine prior to pulling to I don't want to go near them. If mine was bad and theirs looks worse, what do the valve seats look like? (I'm a bad gambler.) Is the head really beyond machining in your opinion?
Also, I thought specials and standard 80's engines were non compatible? They do pop up occasionally locally.

I know Andreas is great parts dealer but if I'd really like to avoid buying another head that is probably in almost the same boat. However if the XS11 guru's say I can't just 3 angle cut it to fix, then I'll bite the bullet.

What I'd like to do is use this as an excuse to BB kit it, throw in new valves, new bearings, check the gears, new valve seals, polish the head and exhaust port (myself), but then I start to feel like that kid in a candy shop.

[3Phase]

You asked but it's your bike, your time and your money.

XS1100s don't usually drop stuff in their combustion chambers or crack the valves and valve seats so it'd be unusual if one of those eBay heads was as torn up as the one you have.

Maybe you have a good 'in' with a machinist that'll do a 3-angle valve job on that jacked cylinder head but that still leaves the banged up piston. If a valve seat is cracked too along with the divots in the combustion chamber and the piston you're going to spend more time and money on parts and labor and fooling with the thing than just taking a road trip up to Pennsylvania to grab that Midnight Special, then dropping the engine in your '80G.

[skids]

Looking at the valve, it does look like there was some reduction of metal. It is difficult to tell because of all of the buildup of deposits. It does not look like (from the pic) that the valve contact with the seat was burned. The neck of the valve is a bit strange looking though...was there some loss of metal there? I am not sure where the valve seal needs to have good contact.

[Bonz]

Thanks ASR, I didn't see pictures of valve stems other than the most recent post. I wasn't thinking the carbon extended up far enough to keep the valve from closing. Now it all makes sense that you had cleaned them a bunch, I didn't see the before pictures just the after pictures.

If you're looking for a reason to do a big bore yes, do it! Those valve seats should freshen right up, find valves in good repair and set your shims accordingly afterward.

Do you need new bearings or do you just want to do new bearings? Unless there has been some serious lack of lubrication or similar, those bearing should be just fine. Again, maybe I missed something in an earlier post?

[AggiesaurusRex]

SO... I'm curious on how everyone cleans their engine for rebuilds, by that I mean the insides and mating surfaces. I've begun the slow and annoying removal of the base gaskets and head gaskets via the razor blade method. It goes a lot like this "eek eek eek eek eek...F&*$ me...eek eek eek.." for about half an hour until I have just a few inches clean and can't stand the sound anymore. Even writing this I can hear it...
When I pulled the cylinder off to send it to the shop a crazy amount of sand and crap dropped onto the rods, crank, cases, everywhere. Basically imagine you have the cylinder off and then threw beach sand, its everywhere. What do I do other than just flush copious amounts of oil through there to try and wash it out?