A forum for owners of Yamaha TTR250 trail and enduro bikes!

Didn't hear anything back on my request for help so pulled the trigger and bought the mag myself - gotta be the most expensive one I have ever bought 

I messaged the seller twice, firstly to ask if I could buy just the scanned or photographed images of the TTR250 article and secondly, asking for a bit more detail as to what the article was about. No response to either message 

I am just hoping the investment is worthwhile and we can all learn something 

Brian

Thank you Steve. I will try and think of it as a Christmas pressie to myself 

I think it's important that we grab every bit of useful information on the TTR before mags like this disappear.

The seller only bothered to reply to my eBay messages after I had bought the mag. Said he had taken photos of the article but that I had bought it before he could post them up  

4 pages apparently on the TTR but two full pages are a photo of the TTR. I have asked him to email the two pages of text so will see if he can be arsed to do that.

Brian

PS It would be really good if we had more info from Geoff Ballard or whoever tuned and prepared his national enduro winning TTR........

 

Congratulations, Brian - Christmas reading sorted now.

Merry Christmas to you and Trish - and everyone else for that matter.

Martyn

Thanks for putting that up, Brian, I thoroughly enjoyed the read..

I love articles and projects about souped up air cooled bikes.
The funny thing about the slow little four-strokes is that they can get along surprisingly quickly.

I was surprised at the initial HP figure they offered of 17 hp. They could have pulled that figure out of their proverbial, CRF230's can make 17 hp.
I would have thought about 20 - 21. 17 must have been still pretty well restricted with the air box and pipe and throttle stop.

There is heaps evidence of XR250's running about 21 HP in stock but derestricted form, and about 24 - 25HP with 280 kits. I believe the TTR motor is at least equal, and IMO stronger in performance to an XR250.

I suppose they did say 22 HP with the short header and muffler.

Oh and I was glad to read the shorter header pipe did give a couple of HP.............. as my shorty is in the mail as we speak!!!

Can't wait to fit that up to my 263. No doubt then I'll be dreaming of a 325/350!!!!

I have OCR'd the text to make it easier for us oldies to read 

 

Brian

 

If you squint hard enough, while holding a piece of cheesecloth in front of your face, the Yamaha TTR250 looks like a small-bore version of the YZ426. Or at least that's what the MXA wrecking crew thought in one of our least lucid moments. Caught up by poor lighting, optimistic expectations and a "never say never" attitude, we agreed to race a Yamaha TTR250 at the World Four-Stroke Championships. It was one of our more bizarre decisions.

WAS IT A GOOD IDEA?

At full-tilt boogie, the TTR250 could barely pass a monarch butterfly. We failed miserably. Riding a bike that pumped out an anaemic 17 horse-power, tipped the scales at 270 pounds and was equipped with enduro lighting, forced us to develop a riding style that was based on holding the throttle wide open, jumping up and down on the footpegs to develop thrust and flashing the headlight to wake up snoozing flagmen.

When the race was over, which was before we got the chequered flag, we put the TTR250 away, hoping that a coat of dust would make us forget. How stupid were we to assume that we could race a 250cc thumper? Apparently, pretty stupid! 

BREAK IT OUT FOR ANOTHER TRY

Four months later, we rolled the  bike out of the dark recesses of the MXA workshop, squinted real hard, dropped some cheese cloth over our heads and said in unison, "With a little work, I bet we could win some local races on a TTR250."

Thus the fairy tale began. It was like Cinderella. The bike couldn't win in stock trim - that fact had been driven home to us at the World Four-Stroke Championships, repeatedly. But, with a little fairy dust.... How much dust? Approximately $1,500 worth.

We loaded Cinderella up and shipped her to Larry Roeseler's Stroker speed shop in Hesperia, California. Stroker is the King of Kawasaki KLX300 hop-ups (another deadly slow and fatally heavy trail bike that we love too much for our own good). We figured that if Larry could make our KLX300 pump out 44 ponies, what harm could he do to our 17 horsepower TTR? We told Larry that there was no limit to how much horsepower he could make, but that our Gold Card peaked out at 1,500 smackers.

CINDERELLA GETS THE STROKER MASSAGE

Here is what Stroker did to our TTR250, and what it meant to us (and our wallet).

Exhaust system: By replacing the hideously heavy stock muffler with a Stroker SX-l muffler, we saved 3.5 pounds and got 3 horsepower on the bottom (and about 2 ponies on top). The cost? $200.

Header pipe: Since the aluminium muffler gave us a heavy dose of pony power, the next step was the header pipe. Unfortunately, the TTR250 didn't dig over-sized header pipes. It gained some power on top, but lost throttle response. Stroker went back to the stock header pipe diameter, but shortened it by 5 inches. This was a sweet move--and it added 2 more horses to our package. The cost? $140. One caveat: if you want to remove the header pipe, remove the front head stay bracket before you even try. Otherwise it is impossible.

If you're keeping track, we are up to a total of 22 horsepower (about the same as a good riding lawn mower) and down $340.

Airbox: Don't tell Al Gore, but we removed all the EPA garbage from the TTR's breather system. We replaced everything, from the crank-case breather to the airbox internals, with a Stroker kit. While we were at it, we carved on the airbox to let more air in. Cost? $35 (subtotal-$375).

Carburettor: The stock carb is made by a company that you have never heard of (their claim to fame is making chainsaw and lawnmower carbs). It comes with jets that are impossible to get. And, while it is a pumper carb, it isn't a very good one. We fiddled with it for a day before giving it the Lew Alcindor sky hook into the hoop (although we used a garbage can instead of a net). In its place, we bolted on a 33mm Mikuni pumper. This is a good four-stroke carb - plus we can pronounce the name. It stopped the TTR250 from coughing in the whoops and over jumps. The carb sparked up the throttle response and allowed the bike to pull hard throughout the range. Price? $325 (subtotal-$700).

Big bore: To get the TTR250 to churn out serious (or at least semi-serious) power, we had to mess with the internals of the mill. Stroker provided a mid-and- up cam (with standard corn timing), head work for better fuel flow; intake and exhaust porting and an 83mm piston (the stock bore is 73mm, and any bore larger than 74mm requires machining the TTR cases). While we had the cases apart, we thought about stroking the crank, but decided to leave something to the imagination (and credit card balance). The end result was a 325cc displacement. The cost? $898 dollars (cams $249, big bore kit $450 and head work $200). Subtotal for the complete project? $1598.

Over budget: Of course we were over budget. And we hadn't even spent any dough on graphics, a seat cover, handlebars, number plate or miscellaneous doodads. No problem - we padded our expense accounts and covered the difference with embezzlement.

HOW DOES IT RUN?

"Why would anybody want to race this thing?" queried the first MXA test rider after practice. "I'm getting pulled on the straights by 125s. How much horsepower does this thing make?"

"About 30 horsepower," we said proudly.

"How much horsepower do the 250s I'm racing against have?"

"Probably 44 or 45," we replied.

"I repeat, why would anybody want to race this thing?" he asked.

"The truth is that nobody would buy a TTR250 to race motocross," we answered. "It's not a race bike. It's a play bike. However, if you owned a TTR250, you could race it. And that is exactly what you are going to prove by getting out there and winning your class."

"How do you suggest that I do that?" he said sarcastically.

"Use the TTR's secret weapon," we replied with a smirk.

"What's that?"

"Electric start," we said with a howl.

Amazingly enough, the disgruntled test rider was so angry that he had been assigned to race a mild-mannered trail bike that he rode with a vengeance. In the end, he won the race. True, he wins his class with alarming regularity, but he had never won it on a TTR250 before (and he vowed that after this week-end he would never do it again). 

 

WHAT'S IT LIKE TO RIDE?

The first adjective that comes to mind is slow. However, slow is relative. To the three test riders who raced it four months earlier at the World Four-Stroke Championship, the 30 horsepower TTR seemed a lot faster. In corners, off-cambers and switchbacks, the TTR250 was a dream machine, but when the track went straight, the two-stroke competition looked like a visual effect from 2001: A Space Odyssey.

In time, every MXA test rider raced the Yamaha TTR250. Most liked it. Most didn't do as well on it as they did on their purpose-built race bikes. But most had fun and wished that they had a bike like the TTR250 (in its 325cc clothing) for trail riding and play racing (which is, after all, what the bike was designed for). To the TTR's credit, we raced the bike with stock suspension (our budget was depleted on the engine). With some oil added to the forks and the clickers turned all the way in, it handled everything but jumps with aplomb. For trail riding, the suspension is superb. For racing, it's barely adequate.

Would any MXA test rider voluntarily race the TTR250? Yes, surprisingly, two out of six stepped forward when the roll call was read.

Number game: The most important step in turning a trail bike into a race bike is losing the enduro foof. Once we replaced the stock headlight with a front number plate, in this case off of a CR250, the bike's personality changed (although not much).

Big enough: In stock trim the TTR has an anaemic 17 horsepower, but after Stroker changed the cam, porting and piston, the little YZ-F wanna-bee pumped out 30 horsepower. To turn it from 250cc to 325cc, the bore was upsized from 73mm to 83mm.

At speed: Speed is relative, but our full-race TTR250 produced twice as much horsepower as the stocker. Unfortunately, that was still 50 percent less than the bikes it faced in the 250 class. The power factor was down, but the fun quotient was up.

Key club: The only problem we had with starting the Yamaha TTR250 four-stroke was misplacing the key. For intellectually challenged riders, Yamaha labelled the two-position ignition with an on-off placard. Thank you.

Wishes and dreams: Yamaha would sell a couple thousand more YZ400Fs if they put this button on it. Electric start makes a four-stroke a thing of beauty. The TTR250 starts every time. It better, because there is no kickstarter.

For more info. see your local Yamaha dealer and call Stroker Speed Equipment at (760) 948-2871.

OCTOBER 1999 MOTOCROSS ACTION

 

 

 

I believe I may have purchased the bulk of this bike on Ebay. An awful lot of boxes check. I purchased the engine as a backup, I think it was $750-$800 at the time ( this was over a decade ago), but then I wanted some electrical bits and then the seller says give me a $1000 and I'll send whatever I have left of this bike. Now originally I just wanted the engine assembly because it had that Mikuni pumper on there, and I figured cores are about $500, and at the time, most motors were still on running bikes so they only became listed rarely. Then I knew the MIK was over $400 before all the tuning hassles. So I figured I'd take a chance on the mystery motor. I'd at least get some money back by selling the carb, right?. At the time all I knew is the rest of the bits said "STROKER" all over it, just as pictured in the magazine article. Perhaps the crank was stroked?(at this point I still don't know)...all I knew was someone dumped some FU money on a TTR, that much was fairly obvious.

So a week or so later a big blue frame shows up fro southern California, with notarized papers, the front forks, front and rear hubs(plus spokes), all the wiring and electrical including the CDI, and if I'm remembering correctly, the airbox and boot. I can't remember if the swinger or pegs were included but I think not. I can't remember because it all stayed mostly wrapped and boxed, and into the attic it all went, where it has stayed for a decade or more. I did not get the seat, shock, linkage, bars, or tank, but I may have the brakes. The seat and tank in those pics look awful familiar and that exhaust system looks identical. The scuffing on that left case cover looks like it could match, but the clutch cover scuffing doesn't ( it could have been replaced with a subsequent clutch job?). OR......the whole thing is just a clone of the magazine bike? I have to assume 4SW built more than just one.

The outfit that built the engine was called "Four Stroke Works" not Stroker. I'd never heard of them, so I poked around searching for TTR250 STROKER, and came up with nada. I think I went to Thumper Talk and there was mention of KLX Strokers, and there was a phone number or email. Anyhow, whomever answered was the actual mechanic that built them, so we proceed to have a nice conversation and try to identify the mystery motor. It turns out they did 2 or 3 versions, I think an 80 or 81mm, the 325, and then the stroked version(340-350cc). I can only remember the basic details as it's been too long in the past now. I did ask him if he used eccentric pin and spacer plate for the stroked crank, and he said NO, you wouldn't be able to identify it visually. Instead they move the crank pin and used their own sourced pistons, Stock rod, and they moved around the compression height. He did say the simple big bores probably weren't worth the hassle, but the stroked version would keep up with the 400's on the trails. He said they only ever did but a handful of TTR'S, very few.

So, It's possible mine is the 325 from the article, and it actually won an MX race...crazy thought.. right?
I'm not going to tear it apart just to find out which version it is....but seeing this article has piqued my interest to investigate further.

mossproof wrote:

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Oh go on, pull it apart before you get it running in a chassis! Otherwise you'll never get round to it and always be wondering what's in there!

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 Well I was assured that this was a running bike, and that it was tuned specifically, to operate with "that" carby, and "that" header and silencer.  Not sure I want to go destroying headgaskets  before I confirm this. I may set up a dial indicator to check the stroke.

mossproof wrote:

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"I may set up a dial indicator to check the stroke."

That would satisfy me! 

Some monster of a TDub you would have then!

RE the TDub, and wandering a bit from Brian's thread, how did you get around the strange countershaft length of the TW motor with the TTR, or is the 250 that much wider that there is no problem?

(For anyone else reading this, the TW engine has an extra long countershaft so the drive chain can get round the super-wide rear tyre)

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The 4gy is wider, and where the kicker plug is, it barely clears the Tdub frame. Rear mounts cut off and new tabs welded, fabbed top mounts,  the rest barely clears the tank, main, and downtube, fabbed lower connector frame. Once you get it lined up you can use the front sprocket from a XT600E, It's offset compared to regular XT600, just enough clearance to sneak past a stock Tdub tire.

Have you ever seen the TW's that run the rear Bridgstone on the front, then a big sxs front tire on the rear? I don't think it would clear that, but it works for stock....The XT350, SR250.. etc.. are too big and heavy to fit a TW frame, but the 4GY fits. The TW motors for stateside are just corked out 125's. The 4GY makes for slightly more enjoyable experience on the freeways.

 

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