rescue project: abused/neglected XR100R

After borrowing an XR100 for backyard and warehouse flat tracking, I finally got one of my own. I wanted a KX65 or RM65 two stroke but got a docile XR100 so as not to be that guy with the overpowered bike who can’t ride it worth a damn.

My XR100 shopping trip produced two candidates and I test rode both. The 1998 had wonky rear suspension with bad driveline lash and something goofy with the steering head and/or forks. The 1994 had a strong low/midrange engine that gave up on the top end like a two-valve Ducati. Neither was maintained very well but they were said to have recently cleaned carbs. I didn’t think the 1994’s problem was carburetion and therefore it was beyond me fixing cheaply and easily, so I opted to buy the 1998. Better the devil you know than the devil you don’t know.

I had tipped my garage balance in favor of two stroke motorcycles and done so with one from the evil empire. For this I was to be punished.















This twelve-year-old doesn’t look like a victim of neglect and abuse. Let’s look closer.

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14 tooth, no make that 12 tooth, front sprocket


dented rim


missing spoke #1


missing spoke #2


rear suspension linkage likely not serviced since Clinton administration


carburetor clamp fastened with a bent tack


bent footpeg

Well that’s it for the quick visual inspection. Let’s see what other trouble lurks inside and start fixing stuff.

The oil was drained and a Yamaha copper washer was added to the drain bolt. I added just under a liter of Shell Rotella synthetic 5W40. Cables were lubricated with silicone spray, Phillips head screws were replaced with socket cap bolts, and levers were adjusted.



The wee little bike was brought to working height.


Costco plastic table (chopped legs), dirt bike stand, PowerStands wheel chock

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The spark plug, which was loose, and one range too hot (CR6HS), was replaced with a proper new plug (CR7HSA).

The parts washer worked overtime and needed a refill of mineral spirits.


Harbor Freight washer + K1 kerosene+ odorless mineral spirits + Dextron ATF + brushes + elbow grease = clean parts


airbox


air filter

After a thorough cleaning in the parts washer, the air filter foam was hand-washed, dried, and got treated with No-Toil oil. The dirt was removed from inside the airbox.

The rear wheel uses 36 spokes, half each of two different part numbers. I had no clue which spokes I needed so I got one of each.


in stock at the Honda dealer in Reno, I shit you not

The tire had to be removed to install the spokes.


There Will Be Blood.


”gynecological instruments for mutant women”

Despite cold garage temperatures, the tire came off easily, without bloody knuckles. There was rust everywhere.

It turns out the wheel needed one of each spoke type. The sprocket interfered with lacing the spokes so it was removed. Two bolts were stripped in the process.


replacing spokes

One of the wheel’s intact spokes had to be removed to lace in one of the new spokes. After installing the spokes, they had to be tightened, and other spokes had to be loosened. It just so happened I had a selection of spoke wrenches included with dirt bike purchases.


KDX200 (?), CR250, and YZ250 spoke wrenches; the cheap stamped one fit the XR100 nipples

I cleaned up the tire, tube, and rim, removing the rim strip and replacing it with duct tape. The tire sat in the morning sun while I ran some errands and came back to install it.


baby powder: it’s not just for wet crotches anymore

This little tool helped me pull the tube’s valve stem through the rim.


with the hook set, the fisherman begins reeling in his fish


the fish successfully landed

That was the easiest tire change ever.


worn Dumbslop should be more slippery on the backyard dirt and hook up more on the warehouse concrete

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The front sprocket had to go.


seriously?


mo betta

The left side cover which covers the flywheel and sprocket had been welded. Apparently the chain had derailed and cracked it after somebody neglected drivetrain maintenance.

With the flywheel cover off and waiting for a gasket, it was a good time to check the valve clearance. Unfortunately, it was a bad time for my hard disk to die and I didn’t have access to the service manual PDF. No matter, I knew just enough to be dangerous. Turn the flywheel to the T mark, use a .002” feeler gauge. Adjust as needed.


so simple even a caveman could do it

It was difficult getting the feeler between the cam lobe and rocker. Wow they were tight. That’s because you’re supposed to check between the tappet and valve step, dumbass. After I loosened the valves the engine made quite a racket when started. After I sought help from BARF and Thumpertalk and recovered my PDF manual, I fixed things and it ran great. I even adjusted the cam chain tension without blowing it up.

Crashes when flat tracking in the warehouse usually resulted in spilled fuel, so I set up a catch tank for my carb’s float bowl drain line, overflow/vent line, and the engine crankcase vent hose.


genuine Yamaha factory racing catch tank, probably the most expensive catch tank on backyard play bike

With a rebuild kit in my grubby little hands, I turned my attention to fixing the rear suspension.


non-rebuildable shock with linkage


EPA Superfund site


partially disassembled linkage


“Well there’s your problem, right there!”


dogbones or wishbone?


Billy Mays here for Oxy-Clean!


maintenance rig probably would have worked just as well as for suspension

The XR100’s rear suspension does not have needle bearings. What it does have is steel collars riding inside plastic bushings. This looks like a job for my favorite new tool, the blind bearing puller.


pulling bushings from the linkage


linkage after cleaning and installation of new bushings, bearings, and seals

I put the shock back on, even though I didn’t have the new fat boy spring for it, because I wanted to test ride it.


rear suspension re-assembled

A test ride would require some kind of final drive.


new 428C chain on new 50T sprocket with half new bolts and nuts and a new axle nut

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The rear suspension worked great on the test ride. No squeaking and no wonkiness.

However, all was not well. With the shock removed, the rear engine mount was visible, and it looked bad.


Oh the horror! Oh the humanity!

That’s a deal-breaker I wish I would have seen during the pre-purchase inspection. It’s just not visible with the shock and wheel on. No amount of JB Weld is going to fix that.



Minor trouble was encountered with the brittle, old fuel line


Speaking of JB Weld, it’s not a good repair medium for a flexible intake boot.


when wiggled, a crack is revealed


crack is more visible with the intake removed

I think I found the cause of the lean bog. Another $50 into this money pit.

Functioning rear suspension only made the problem in the front more obvious. The test ride pointed to the steering head bearings. The front end was next on the list.



ProTip: Don’t put the registration sticker on the fork above the triple clamp like the bureaucrats tell you to. They don’t have to work on motorcycles and they don’t care that you do.


designed to fail

Either put it below the triple clamp so you can slide the fork out without hindrance, or put it on the frame. After all, the frame is the motorcycle.


top triple clamp off

The company that gave us oval pistons and gear-driven-cam V-4 engines also gave us loose ball bearings in the XR100 steering head. When not held in with grease, they will fall the floor when you remove the steering stem from the head.


balls should be arranged on the race on the bottom of the stem

A clever mechanic might be prepared for dropping balls with a magnetic parts dish.



A more experienced mechanic might be prepared with a blanket to catch the dropped balls. I ended up searching for balls on my table.



I also searched the garage floor. Spent primer, spent primer, ball bearing, spent primer, live primer.



Finally, with a magnet, I picked up the last of the balls from the head itself.

Most of the balls managed to stay in the top race.




”One ball bearing, ha ha ha. Two ball bearings, ha ha ha.”


36 of 42 balls

I’m sure I didn’t lose six balls, which means it started with less than 42. I ordered extras.

What little grease remained was hardened.


stem nut/cover


clean lower race

I’m waiting for stiffer fork springs, stiffer shock spring, left cover gasket, intake manifold and gaskets, and balls.

(to be continued)

Nice narrative. I look forward to part 2.

what're you gonna do about the back of the engine? get it welded?

Very cool. Keep it coming

good chuckles so far!

Junkie said:

what're you gonna do about the back of the engine? get it welded?

Click to expand...

Ride it as is. I'm no expert but it's not weldable. (Maybe if it was built up and re-drilled?)

Get some cases on fleabay and rebuild it if it proves to be a problem.

Hey I found another steering head ball bearing on my work table last night.

don't bother counting balls, get tapered roller bearings from all balls
also, the buchannan spoke kit will prevent furthur rear wheel problems, those stock spokes are crap and will continue to break, especially the way you ride. get the oversize ones and be done (until the hub breaks)

Damn I need a parts washer.


And a garage to put it in.

Great story. Please continue. Thanks.

augustiron said:

don't bother counting balls, get tapered roller bearings from all balls
also, the buchannan spoke kit will prevent furthur rear wheel problems, those stock spokes are crap and will continue to break, especially the way you ride. get the oversize ones and be done (until the hub breaks)

Click to expand...

Tapered bearings = $$, Buchananan spokes = $$$ (really stupid on a bent steel rim) ... I really don't want to build a high-bucks bike.

I was looking at complete used wheels on fleabay. There's one currently at $151. Iidiots! You can buy new HD spokes and a new aluminum rim for that.

The way I ride huh? How bad can it be on a warehouse floor or backyard circle track? For sure if I take it off a sweet jump it's doomed.

Nice writeup, I think you've just given me the gumption to pick up my ol' 96 xr100 from my dads house and start gettin it ready for flat-track duty. What kind of tires are you thinking?

The tires are on it, Dumbslop 739. I said I don't want to spend money. If one or both doesn't stick, I'll get Michelin Starcross knobbies, I guess the hard terrain version. The cheater CRF150 I rode in the warehouse had Starcross tires that stuck almost too good. Dirt track or rain tires would be the hot ticket but I don't know of any in these sizes.

Well, looks like those starcross' are the hot ticket, not too spendy either. Hopefully i'll see ya round the warehouse here in a few weeks.

Parts have arrived and been installed.

The flywheel cover gasket arrived and before I installed I took a picture of the weld repair:



I got this used footpeg on fleabay:



Color doesn't match but it's straight:



Here's the new intake manifold. Also pictured is a screw in place of the nail holding the airbox boot to the carb.



Forks were drained and cleaned. The springs are about the diameter of a skinny thumb.



The forks got stiff new BBR springs and Motul 15W oil. Their accordion boots were junked and neoprene socks are helping save the seals.



Two-thirds of #108 were applied on two-thirds of the number plates.



The front plate got a special yard sale sign.



I have a stiff new BBR shock spring ready to go but it's a "Veera Vest veekend" so my man with the spring compressor is out of town.

A test ride proved the fork springs work very well. There's still a little driveline lash I can't quite figure out. But it's ready for backyard and warehouse flat tracking.

Very nice writeup! That's the problem with a cheap bike - they're never as cheap as you hope in the long run...

Which HF parts washer is that? Does it recirculate the fluid? I've been thinking about getting one.

I don't know which HF washer it is. It's about the size of a square 5 gallon gas jug laid sideways. It has a pump and an articulating hose. Being HF stuff, the plastic pump parts are crap; the filter won't stay on the pump and the hose won't stay on the pump.