The home of Aussie Vintage Motocross

Confessions of a Thumper Rider (Part 1)

These days, I race vintage MX on a small bore 2-stroke - an RM125M. I've also got a 1980 YZ250 under restoration. And I race some modern grasstrack on an 05 YZ125. Before that were a few more bikes like an RM400N and a Husky CR500. All 2-strokes. I like the little zingers especially - light, fast, manoeuverable, and cheap to run. Yep, I like my 2-strokes.

But it wasn't always that way.

Like many I started out on a small bore two-stroke - a GT80MX way back in 1975. But I was never much into motocross, rather I preferred trail and play riding. So for a few years my choice of bikes reflected that. A TS100 was followed by a DT250A and a few other such things including a DT250D, that porky monoshock thing that at the time I actually thought was a street legal MXer. One sunny day though came an event that was to change my life - a bit anyway.

Yamaha had released the TT500C, something I thought then (and now) to be one of the best looking dirtbikes ever. I drooled and lusted over its white and red tank, its svelte lines, and that lovely big downpipe (no idea why but I love the look of downpipes). Unforunately at the time I was too poor to be able to afford one, still paying off whatever traillie I had then. A mate could though and so it was on this particular day that he let me ride the thing.

Well - what can I say? I was hooked. It had this lovely big comfy seat, it had a wonderful waffling exhaust note, and it had torque to die for. Twist the throttle and you were rewarded with a long surge of power the like of which I'd never experienced. Hardly surprising given that DT250s are not exactly fireballs.

I had to have one.

But just like my success with Julie, the chick at the local disco I kept making eyes at, it wasn't to be. So, for a couple of years I kept dreaming until sometime in 1978 Suzuki dropped the SP370 onto the market. Our local Suzuki dealer was a sort-of mate and waxed lyrical about it. I took the demo bike out for an extended fang and thought he was right. Not as fast as the TT500, but not bad either. Ugly as, but maybe I could learn to live with that.

So I bought one.

And right there I was introduced to a sad way of life that afflicted quite a few people at that time. Now, ADB was my bible, and they were pretty savage in their criticisms of 'thumpers'. You'll probably remember how they never could quite 'get' the idea of owning a pile of crap like a Jap dual purpose four-stroker. Even worse in their view was the way people spent a fortune trying to get one to go fast and handle good.

But they just didn't understand.

Buying a four-stroke back then was really a fairly eccentric thing to do, at least it was for those who were serious about racing dirtbikes. Sure there were people who could do OK on one, I remember a few TT500s winning various enduros, and the Yank mags were full of articles about hopping up your XL350/TT500/SP370. But by and large, they weren't great dirtbikes.

Luckily, I wasn't a serious dirtbike racer, nor was I actually any good. Our riding was mostly confined to trailriding, riding around the streets, wheelies, drag racing and hanging out at the milkbar. And in that world, buying a thumper cos it looked and sounded great was as good a reason as any.

What made it difficult though was that as time passed, our riding got a little more serious. And that big old SP370 was really a dog when this happened. My mates bought PE250s and IT400s and the old DTs disappeared. Trailrides became fairly hectic affairs, hammering through the scrub as fast as possible and hoping like hell that the timber trucks weren't on duty that day. I found out pretty quickly that the SP wasn't really in the race.

So, I decided to 'hot er up'. Not buy a decent bike, you'll note. Nope, I was a thumper rider, and I was gonna prove that the SP could be competitive. So, with that in mind I scoured the mags, saved my dollars, and began spending up big. In very short order, the SP gained a set of Boge shocks, an Open Road plastic tank, Peter Allen exhaust, 36mm carby, modded airbox, Megacycle cam and S+W valve springs, Protec HiComp piston and so on. All the lights came off and she became a stripped down trail weapon. I was pretty impressed!

Trailriding improved. Sort of. The thing was faster, but not by that much. Now I was neck and neck with the PE250s in a drag, but the IT left me for dead. So did other mates TT500s. And even a ratty old DT360 that some flanny wearing wanker was riding with us one day. But it did feel a bit lighter, and it did seem to handle better.

About now though, we discovered enduros. Not your serious ACU approved ones, more your black event type Pony Expresses and so on. A couple of these and it came home in no uncertain terms that the SP was OK on the way to work, but in the dust, heat and nasty horrible rockery of some of these enduros it was lacking. I started to crash as I over ride the thing trying to do what guys on IT175s seemed to be doing easy.

I remember one particular crash very well. The day was damp, it'd rained overnight and there were still a few light showers. So the place was wet. But I was actually going OK and was somewhere in the top half of the field. I caught a guy on a 2-stroke, can't rememebr what now, and we had a bit of a tussle through some tight single trail. He just had that edge in the corners but I had a bit more poke on the straights. Finally, we got onto an open trail and I knew I had him. I gave her the berries and dived past just as we came to a large puddle across the trail. I thought it'd look cool and really rub it in when I wheelied through it in front of him. Well, it would have, if that's how it went.

No, what really happened was that I got on the back wheel just fine but the seat was wet and slippery and immediately I slid off the back. In itself that's no probs, but sadly at the same time the wrench of my weight ripped my left hand off the, you guessed it, wet and slippery grip. So here I am, on the back wheel, hanging off the back and with all my weight now hauling on the throttle. The SP simply accelerated, careened out of control sharply to the right, into some long grass and fair into a small sapling. SP and rider promptly separated with the SP cartwheeling unceremoniously to a halt against another small sapling. Me, I was flat on my face in a patch of black sticky mud. As I got to my feet, my now victorious competitor idled by, gave me a pitying glance, and with a shake of his head disappeared up the road. I think I finished last that day.

And that became the way of it. I got beat in the drags, I crashed my brains out in enduros, I couldn't keep up on trail rides, and the bike was a pain because the poorly jetted carby caused it to stumble and fart most of the time. And of course, the local constabulary took great delight in hounding me. I was lucky though, cos even getting caught one day after pulling a decent mono and having no working lights, no mirrors, knobby tyres and an overly loud exhaust only resulted in a lecture and having to push it home. But the writing was on the wall.

Of course, I knew what the problem was. It didn't take too much thinking to conclude I'd been had. The SP was a piece of crap. What I really needed was a 500 Yamaha.

To be continued...

Here's the SP in all its glory. The shot with the big tank is it in its final form with all the go-fast handle good mods.

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Comment by Graeme M on November 29, 2009 at 1:08am
Well, you know not being a very good rider means I have no idea what handling actually is, so while I could tell that an IT175 works better than a TT500, it wasn't THAT pronounced. So most of the time I just made do. Twist the throttle, it goes. Turn the bars, it steers. That was good enough for me! I must admit I am not even sure that I could tell the difference nowadays. People talk about offsets and spikes in the compression stroke and pushing from the centre out and so on. For me, if it all goes up and down and I don't fall off, it must be OK. So SP370s and TT500s were OK in my book.

From the sounds of it though Brent, you have a far better idea of how it all works and I remain impressed by your dedication and effort to make a 500 Yamaha handle!
Comment by Brent J on November 29, 2009 at 12:39am
I started out on two strokes but had this secret dream of building four stroke MX bike. I bought every magazine with a four stroke hop up article and dreamt of building an SL125, XL250/350 into a two stroke eating monster. The ideas were there but never the budget to follow it up. I even had a liking for pommy thumpers and after I saw Reg Dixon at QE2 park during Gaston Rahiers trip to NZ in '75, a CCM would have been the ultimate dream.
I never owned a Yamaha 500 and have to admit that I never even rode one until I bought mine in about 2001.
I loved the motor but was sadly disapointed with the handling. Since then I've embarked on a sad oddessy to build my idea of what the XT/TT could have been. WIll I ever get it right, probably not but I'm having fun trying

Comment by Jerry Healy on November 27, 2009 at 7:29pm
Love your work Graeme. Can't wait for the next episode..... Jerry
Comment by Graeme M on November 27, 2009 at 12:26am
Ahh, that story does take me back. That's exactly how it was. I remember buying my DT250D because for the price, around the $1000 mark, it was a few hundred cheaper than an XT500 and that seemed an insurmountable difference. But it was dumb logic because had I waited a few months I could have afforded it and the 500 was so much better to ride than any DT.

What stands out in my memory, and remember I had no exposure to real race bikes and was a trailrider, was how good that damned XT/TT looked and sounded. At that time I lived to do wheelies and the old DTs were a bit average. I remember standing in the main street in Bundaberg Qld and watching a real live TT500 accelerate around a corner, and as he gassed it through second the front just lifted about a foot and he held it there. I was gob-smacked. How cool!!
Comment by GMC on November 26, 2009 at 11:51pm
Theirs not really any logic to what we drool over is their. I have to admit to drooling over the TT when it first came out too. Some mates that were into racing MX poo pooed the TT as a waste of time. I didn't care, I just wanted one. I remember when I was turing 17 3/4 I was ready to buy something, I had saved nearly enough from making mocasins & from my sheetmetal apprenticeship to buy one. At the time the XT was just coming out & they were around $1300, the DT400 was $1100.
I was scratching to make the $1100, the $1300 seemed so far out of reach & then a price rise came in. The DT went up to around 13 something & the XT was about $1650.

I had missed the boat so I went searching secondhand. I test rode a registered TT in a carpark in Glenroy that I could afford but the compliance plate bullshit had just started & I was nervous about getting a road worthy for it. I was about to grasp the freedom of my learners permit & I didn't want to be stuck with something I couldn't ride on the road.

Then I found the local bike shop, K & J, had a DT 400 in stock & at the old price of $1100 so I went up to buy it, wondering how I was going to come up with the on road costs I was surprised that he threw them in. I now had DT400 ready to ride away, this was a better deal than any of the city shops would do & I wondered why he didn't screw me for the updated price. Their was madness in his methods though as I went on to buy 4 other new bikes from him.

I was in heaven on my DT until my mate Dave turned 17 3/4 a few months after me & he bought a XT500. He was a bastard to go riding with, I would be riding along blissfully until I would look in my mirror to see him monoing while he was following me. That XT would always leave me for dead in a drag too. One time he missed a gear & I thought I had him, well I did until he found a gear to engage & he would catch up & pass me again.

They were good times but an altercation with a truck brought all that to an end, I swore off riding on the road & got more into MX & Enduro bikes after that.

I bought an XT a couple of years ago but need to rebuild the motor & get it registered, then I might relive some of my youth again.

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