From: alanf@tridom.com (Alan Fleming)
Subject: Dirt Donk Experience
To: seriders@dorje.com

Okay, here is my review of my first dirt experience with a rather long lead in.

The History:
I used to ride pillion on friend's dirt bikes when I was a kid but never got an opportunity to take the controls. I did get a chance to ride some street bikes during this time but didn't own one until I bought my '78 CB400T Hawk in 1990. I then moved up to an '88 GSXR1100 and now I'm planning on starting road racing with a Honda FT500 Ascot. What has concerned me since I hatched the idea of road racing is that I'm not very comfortable sliding a bike around, something done regularly now on the race track. In an effort to overcome that reluctance to slide around, I decided I'd look for a little dirt bike. Not long after that, I saw an ad on a local Usenet group for a $100 dirt bike, type unknown.

The Purchase:
I went over to look at the bike and found a 100cc Yamaha (later found to be a '75 MX-100) with "some boring" and a dirt track pipe. The bike had been sitting for a year and wouldn't crank, although the engine turned over fine and without any ominous noise from the bottom end. It was intact, though battered, and came with a spare, slightly bent rear rim. I gave the guy $90 and started to load it up. He then mentioned that his roommate had a bike he'd be willing to sell as well. When I looked it over, I found that it was another Yamaha, again of unknown model. This one was in much better shape and was an enduro. (with lights, electric start and oil injection) This bike was claimed to start but would die when the throttle was moved off idle. In addition, the owner would throw in for free a larger (equally old) motocrosser with a siezed engine and some missing parts.

Now that I was too broke to take advantage of this, I hussled home and called my longtime friend, riding buddy and old bike nut: Troy Casey. Sure enough, he was interested and a few days later we picked up his bike (later found to be a 125cc '72 AT1) and the junker (a '77 Yamaha YZ125). I paid Troy $20 for the YZ and added it to my "fix one day" collection.

The Bike:
A more careful survey, after I got the bike home, I uncovered the following:

• The fork seals and dust covers were shot. In fact, the the forks were empty of oil and duct tape held in place with hose clamps were being used as dust seals.

• The dirt track low pipe wasn't held in place with much of anything and was only pseudo mounted to the swing arm!

• The throttle cable had apparently be sourced from a different bike and provided liberal play.

• The front brake cable's adjuster was broken and the brake ineffectually loose.

• The oil injector and associated gears had been removed.

• The tires are nearly dry rotted through, though they have plenty of knobbie left.

Finally, last weekend, I changed the oil and played around with rolling the bike around in gear. This seemed to free up the clutch. Then Troy arrived and took The Dirt Donk for it's inaugural ride down my driveway. (and immediately popped a wheelie) I also rode it for the same 20 ft and declared it a success. We immediately made plans to go riding since he'd gotten the AT1 running. I had swung by a shop that had an old aftermarket pipe for a '74 MX but we couldn't get it to fit. Instead, Troy did a masterful job of strapping the old pipe in place with coat hangers. With Mike Mitten and Troy's brother Dean in tow we headed out for a powerline just outside Atlanta (near Troy's house).

For the next two hours, we wheelied, slid, bounced, flailed and laughed. Dean was the first to dump when he lost the front end. Troy went for a more spectacular crash when trying to jump a little hill. Apparently, he and the bike had different ideas on which way to go and, unable to compromise, each took their own route. Mike, being shier, went over a hill and quitely dumped in privacy. I'm the only one that didn't drop, though not for lack of trying. Its just that everytime I came off the bike I managed to come back down on it rather than off of it.

The Stats:
Unknown, but the MX seems to pull much stronger on top than the AT1. The AT1 comes off the line stronger (and more impressive since it's smaller wheelbase makes for easy wheelies) but the MX runs away when it comes on the pipe. The MX is also much louder, despite having a lawnmower muffler duct taped onto the end of the pipe. The AT1 was much easier to slide around, presumably because of the enduro tires and flatter (for a 2-stroke) power delivery. Obviously the suspension on the MX sucked. The suspension has very little travel (perhaps 3-4 inches in the rear and moderately more in the front) but the lack of fork oil meant it was easy to bottom and pogo'ed mercilessly after a big bump. I just got in the habit of gassing it before hitting something to lighten the front end. I also noticed that the bars offer an incredible amount of leverage, making it extremely easy to throw into a corner. I kept finding myself turning too hard, too quickly and having to readjust my lines mid-corner. Gas mileage was probably terrible but we used less than two gallons of gas. No speedo/odometer/ reserve made it difficult to determine how much riding that came out to be. Maybe I can rig up one of those bicycle speedos in the future.

The Result:
I like it a lot. I was unwilling to spend any more money on the bike until I was sure the engine/tranny was usable. Now that it has withstood a day of playing around, I'll spend the money required to make it safe. I'd love to find a pipe that would work but Yamaha no longer sells the stock pipe. Local boneyards haven't turned up anything so I'll try some national places next.

I've also read the wreck.moto.dirt FAQ and gleaned some info from it. I'll also grab a few dirt bike mags and see which one seems the most useful to an occasional wanna-be trail rider.

The Gear:
my street helmet	Shoei RF200
my street boots	Alpinestars GP
my street gloves	Olympias Kevlar
a pair of jeans	Levis
a t-shirt
(I'd intended to bring a long sleeve jacket but rushed off without it)

The Cost:
Bike:	$90
Chilton's manual:	$22
Spark plug:	$2
2-stroke Oil:	$1.50
Crankcase Oil:	$1.50

The Future:
New tires:	$170
brake cable	$12
throttle cable	$15
fork seals	$20
fork slider bushings	$25
Some real dirt gear

Then there's always that YZ-125...

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