Well, it finally happened after 28 years, 15,000 plus miles, 6-7 years of neglectful storage, and a short span of Dual Sport riding from last February (Laramie Lap) through June 09. On Mother's Day weekend in May, she popped smoke on me for the first time at start-up. This soon settled down but oil consumption became very noticeable during moderate use. I eventually resigned myself to the fact that I would need to constantly keep it checked and filled until I could find a shop who could get it in for a rebuild. Three weekends ago on a Saturday morning, I decided to give the bike a once over before spending the rest of the day mowing grass. I gave her one kick-nothing (she had been sitting for over a month). Then, as I started the second kick, N O T H I N G ! No compression! "Nada! Zip! That's all she wrote! I rolled her back into the garage to await further consultation with various specialists.
Number Two/Aaron continued to encourage me to find an answer to the question of when we could get her in for a complete work-up as he wanted to get together for some more rides. Nothing shaking until after Sturgis! He called and said to bring her on down when we came to see them and he would give it a go. It pays to have a son who rides who is finishing his Masters in Mechanical Engineering! Anyhow, he has the XT and we will post photos and update the report as work progresses. Hope to have things done and zipped up in time for the Fall Rally. Still have one grandson on the way up in Farmington, MN, so I hope that doesn't throw too much of a wrinkle in the mix. We've talked it over and plan to address the piston, rings, hone the cylinder (only as much as is needed to clean it up, i.e. .10 or.20 over), take care of the valves and valve train, add an additional oil line hook-up to the mix so the intake and exhaust rockers are lubed, put new sprockets and an o-ring chain on, new drum brakes, and maybe if the well hasn't run dry by then and the fates smile down on us, we might even do a little something with the suspension-front and rear. Otherwise, if we win the lottery between now and then, we'll send her off for a total balance and blue-printing and get ourselves two new WR250Rs to ride in the meantime!!!
Have a great remainder of the summer, take care riding around during Sturgis, and we are looking forward to seeing you guys at the Fall Rally! More to come...
Alright, this afternoon, I got a start on the teardown. Mostly I want to get these pictures up so that Crazy Uncle Larry knows what he's dealing with. I also look forward to any advice or suggestions from those who've done this before. This is my first attempt at a top-end rebuild. Notice how I'm doing it to someone else's bike, right?
I rounded up my help and dug in.
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/DSC05582.jpg)
Trace of an exhaust leak. I'm thinking a little permatex ultra copper ought to seal that up on the rebuild.
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/DSC05580.jpg)
Here's what I have under the stator cover. Hope the germans can hook you up with the 12V goodness.
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/DSC05584.jpg)
After a few hours of wrestling, I got it out.
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/DSC05586.jpg)
Lining up TDC so I can find it later.
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/DSC05587.jpg)
I pull off the head, and am stricken with horror at the sight of .... TROGDOR the BURNINATOR!!!
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/trogdor.png)
Sure enough, the lack of compression is due to the exhaust valve not sealing. It's toasted.
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/DSC05589.jpg)
Anyone have thoughts on what typically causes this? The plug was a dull sooty brown, so I don't believe it was over-lean. I initially figured the white smoke event was a valve guide seal biting the dust, but would excess oil cause the exhaust valve to shell like this? ???
There's still quite a bit of carnage left in the cylinder.
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/DSC05592.jpg)
The piston skirt has a bit of scoring, but nothing major.
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/DSC05593.jpg)
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/DSC05594.jpg)
The cylinder was bright an shiny much to my surprise. The crosshatching was gone on top, but still visible toward the bottom.
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/DSC05595.jpg)
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/DSC05599.jpg)
This is how she sits for now. I need to get some tools from work so I can actually check the specs on the piston and cylinder, and pull the valves out for a proper look.
Jug with blue towels. Note bungy to the rafters.
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/DSC05600.jpg)
Not a whole lot left to it. Thumpers are great because they're simple. Old thumpers anyway...
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/DSC05601.jpg)
oh right... the big valve (the toasty one) is the intake not the exhaust.
While I was in the garage, I was doing a little preventive maintenance on the mighTTy 600. This is how you know when it's time for a new sprocket, I guess.
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/DSC05612.jpg)
All of the teeth are busted off, and it was just starting to slip the chain on the rough stuff. I feel like I should own a KLR.
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/DSC05614.jpg)
I do like this method of sprocket attachment much better than the bolt on type of the XT. I can change the sprocket fairly quickly, so I got a new 14t(stock) and a new 16t for more top speed. I'm not sure if the chain will fit both or not. I put the 16t on last night, and cut my fancy new chain down to 114 links instead of the stock 112. We'll see what it looks like fully adjusted.
Need one those little popcorn icons like they have on advrider. Keep it up, good stuff!
that sprocket is impressive. must be the original. i've never seen one that bad before. props!
Time for some forward progress here. I got the head and cylinder back from the machine shop. They bored and honed the cylinder, decked the cylinder and head, installed new valves, guides, and seals along with a new valve grind, cleaned everything, and supplied me with a new gasket set, and a Wiseco 10:1, .020 over piston. I ordered up a new cam chain, tensioner, and guides this evening, so perhaps the XT will breathe by the weekend? We shall see. For now, here's some shots of the fresh parts.
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/IMG00201-20090831-1942.jpg)
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/IMG00202-20090831-1942.jpg)
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/IMG00203-20090831-1942.jpg)
Masked for paint. Masking is one of those things where "Hard work may pay off over time, but laziness always pays off now." Here's my 2 1/2 hour tape job. I hope it works, I'm not a painter. Might try the paint tomorrow night.
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/IMG00205-20090831-2136.jpg)
I have a diagnosis of the engine condition that led to its failure, but comments are certainly welcomed.
The ultimate death of the XT was cause by two primary conditions. Number one, wear. It was old, and somebody used it too much when it was new. The cylinder was a little oblong, lost its crosshatch, the rings were worn, the piston was worn,.. you get the idea. Second, the bike was running too lean. In the pictures above, the stuff on the valve that I thought was casting, was in fact really hard carbon deposit. I'm thinking a lean condition caused excess heat in the cylinder, and combined with the wear, caused some type of minor ring failure. The engine started to burn a lot of oil, which sooted up the valves and cylinder, and may have led to poor seating of the exhaust valve and the heavy coking on the intake. The oil buring masked some of the lean mixture indicators, but after the exhaust valve got blasted clean at the machine shop, it shows clear signs of pitting. My recomendation is to of course richen up the mixture a la jetting or newer more adjustible friendly carb. As an air-cooled single, any additional oil capacity or cooling could help, as would hosing the mud and gravel out from between the fins to encourage cooling. Finally, a sharp eye should be kept on the valve adjustment. Every 2000 mi or less on the old iron? That's all for tonight. Tune in next time for another episode of 'This Old House Bike.'
Dude! YOU DA MAN!!!
THANKS FOR HEADING THIS UP!!!
That is looking nice. As for the taping job, remember...I ain't a painter either!!! And, all we're going for is coverage and ride-ability. She's for GO! not for SHOW!
Seriously, hope this hasn't taken too much of your time away from your own projects, work or most important-the family! I really do appreciate what you've done. Hope to see you this weekend and then we can confer on carbs.-Dad
Got some paint sprayed last night. 2 tack coats and one medium coat of high temp semi-gloss black. One coat of clear. I had a couple runs where I got heavy handed, but I'm otherwise happy with the results. The pics came out poorly, sorry bout that (cell phone). I'll try sanding the fins out tonight, then maybe apply some clear there if the paint's not still too gooey.
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/IMG00211-20090901-1943.jpg)
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/IMG00212-20090901-1944.jpg)
Looks like fun. Your head looks like it's brand new!
ok, got the last coat of clear on after the sanding on Monday:
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/DSC05704.jpg)
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/DSC05705.jpg)
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/DSC05706.jpg)
I like how it turned out, even though it's a little rough, but it just makes the rest of the bike look old and dirty. hmmm.
Checking my ring end gap.
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/DSC05709.jpg)
Tuesday night before the fall rally, I'm getting started on the assembly. Everything looks good, until.....
NOOOOOOOO!!!!!!!!
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/DSC05711.jpg)
Yep, I made about the biggest newb mistake and busted the second ring while trying to use an automotive ring compressor. That was extremely frustrating, as it seemed that I would now have a hard time getting it ready to go by Friday afternoon. I go directly to the internet (where else does one go in times of trouble), and got a new ring set coming overnight directly from Wiseco. UPS to the rescue. This time, I just used the chamfer on the bottom of the cylinder and a little screwdriver. Worked like a charm.
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/DSC05713.jpg)
I replaced the cam chain, tensioner, and guides on a whim. The chain is not stretched at all - oh well, at least I don't have to wonder.
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/DSC05710.jpg)
I did drill out the jets in the stock carb. I knew Crazy Uncle Larry was getting a new one, so I figured I couldn't tear it up too bad. I just went the next size up in number drills on the main jet and pilot jet/emulsion tube.
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/DSC05716.jpg)
Well it's all back together this afternoon, since the local dealership happened to have a Vmax exhaust doughnut that fit just right. There was only one thing left to do...
(http://i250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/th_MOV05717.jpg) (http://s250.photobucket.com/albums/gg264/hudlenutz/xt500%20rebuild/?action=view¤t=MOV05717.flv)
Woohoo!!!!
Took it for a short little jaunt to get a fresh load of premium gasoline this evening. The biggest differences are the smoothness of the power and crispness of throttle response. The XT went from 499cc to 502cc, 9:1 to 10:1, but mostly it went from old and busted to new hotness. I'm impressed.... but mostly, I'm impressed that it runs after sitting in a heap in my garage.
Coming up in the next episode, watch as we release the XT back into the wild - it's natural habitat in the Black Hills of South Dakota.
Checked for leaks, checked the cam chain tensioner again. It is shaken down and ready for break-in. I saw over on the rally thread someone suggested the moto-man method. Crazy Unlce Larry, it's your bike and you're certainly welcome to break it in as you see fit.
I think the method is sound. There's a little too much hype on the website for my liking, however.
...and I think I'm done for tonight - what a satisfying update. :D
:thumbsup
Always a satisfying feeling.
Wow I think he owes you a 12 pack and a back rub.
Naw, nothing as simple as a back-rub! He's probably going to try and hold out for a trip to Moab and a run on the White Rim Trail sometime in the coming year!!!
Bottom-line...his older brother and Number Two/Aaron are a couple of real stand-up guys that I'm proud to call my sons!!!! Just wish we could the older son out here to ride with us. One of these days, maybe. We talked about keeping our eyes open for an XT350 or TW200, something we refer to as the "new guy" ride, so we could help him make the switch from four to two wheels when he returns to SD for a visit. So, we'll see.
Ooops! Time to go make the apple crisp and peach crisp!