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Thread: Bought a TDR250 2 Stroke Project Bike.

  1. #1

    Default Bought a TDR250 2 Stroke Project Bike.

    I've been lurking the net and UK forum searching for Yamaha TDR 250 information and inspiration...
    I have a little Kawasaki KMX 200 with only 3,000km from new (Single cylinder 2 stroke with 30 bhp) I've been using to pop down to the stores with but poor Kermit doesn't have that much get up & go!

    So I've been hankering after a Supermoto style bike for years & always find myself looking at Honda CRM 250's & 2-stroke KTM's, even big thumper Hussabergs, but their 20 hour engine life (Before needing a refresh) and uncomfortable seats put me off (Despite the riot I hear they are to ride)!

    Then I remembered the TDR250! - 50bhp 2 stroke twin - often described by owners as the most fun bike they'd had in the past.
    So I started looking around and they're not that sought after here.... & have good potential for modification.
    By doing some google searches over the last couple of days I realised they're still well rated as fun bikes.
    So I searched online and found one in good shape with only 11,300km for a decent price. I bought it!
    I'd already pre-promised my wife I'd sell the KMX200 (Which I'm bored with, really) to help fund the change to the TDR.
    The new bike should be here sometime next week, I expect...

    Not too keen on the red metallic non original (Lexus?) colour, but apparently it's been professionally sprayed on. It does look fairly tidy & runs well so the seller says. Mostly I wanted a rust free bike with low mileage which it is - aside from the rusty spokes which won't be on the bike for much longer anyways.
    All of my machines get modified so before taking the plunge I did a little research on alternative swing arms, upside down front end, Excel (Or other) 17'' Motard rims, complete exhausts with larger expansion chambers, re-jetting, reeds, better brakes, suspension (Probably a Maxton shock & fork re-work) hidden indicators, carbon bits, etc.
    I like top quality things for the job so I don't have to make changes twice or more. I don't care if it costs more than the bike's worth - this one should be another keeper, I reckon...
    Maybe I should be getting a Simpson Bandit helmet too...

    ...It might become something a bit like this one, I found as an example:

    Won't be a project I do very quickly as I have my family & home to share my spare time with, but looking forward to 1st riding it and 2nd taking it apart and making it a lot better :).
    The SP2 is being used less and less these days, and the VFR is more practical for getting into Tokyo but I wanted something smaller but big fun to get around with locally.
    Looking forward to making this one a small road hooligan tool.

  2. #2


    The upgraded swing-arm and USD forks with Excel rims really make the bike look very modern.
    50hp in a small package is fun. I used to have an RM250 street registered. 90Kgs and close to
    50hp with some mods
    Apexmoto Inc - Dyno tuning, engine/chassis/suspension upgrades, repairs, shaken, tires & changing with balancing, graphics printing, stickers, media blasting, painting & powder coating.

  3. #3
    Join Date
    Jul 2010


    Nifty Project ! Looking forward to updates. 50bhp from a 250 is not too bad

  4. #4
    Join Date
    May 2011


    How is this project going ? Fantastic bike and ahead of its time styling wise.

  5. #5


    Quote Originally Posted by martym View Post
    How is this project going ? Fantastic bike and ahead of its time styling wise.

    Over the last few weeks the TDR got transported to a hub in Chiba where I could collect it yesterday with a friend armed with a new registration plate & riding gear. It wouldn't start easily but I figured it had fouled plugs from having been been run cold several times and now as it was finally going on the open road would clear up. For ease, we bump started it down a hill and I left shortly after to try & beat the rain before I got home some 70km away...
    The engine started first kick this morning, so it seems I was right about the plugs...

    Didn't get much of a chance to try any corners on the way home on that first run aside from weaving between cars whilst exploring the performance, but my first impressions were much as I'd expected. Soggy standard suspension with too much dive under braking, inadequate front brake and the engine runs out of puff as it nears the redline, although I got close to an indicated 170km/h in the pouring rain, which wasn't too bad for a naked-ish bike with brick-like shape and not a lot of torque. Handles OK for a standard bike and is fun to ride. I'm probably being a bit harsh in judgement, many would think it's fine.
    It certainly has good potential & I enjoyed popping down to the local hardware store this afternoon on it.

    Before seeing it in the flesh I'd already bought some recent Honda CRF250 upside down forks (Which can be shortened if necessary), CRF OEM yokes and a complete 3LN swingarm assembly from an FZR250.
    Once I try these bits on with modifications as required I'll look to ordering some custom made wheels from a Stateside or UK supplier, probably 3.5 CRF hub front & 4.5 rear with TDR hub for ease of fitting to the swingarm. Being a CRF front, there are many upgraded front brake kits and caliper modifications. I'm interested in these and wondering if it was wise to buy the used original triple tree. I guess I can sell them on Ebay or something - but at least I can try fitment before splashing out on these triple trees:

    These are the forks bought:

    For a long time my bikes have had Maxton suspension, so once I have it all fitted and set up - knowing preferred ride heights, etc the forks & rear shock will come off and be sent to the UK to have the forks shortened and modified so spring rates & damping will match a custom Maxton shock.. All this combined with some sticky rubber should make for a bike with much higher limits than standard but more importantly, predictability and control.

    Stan Stephens in the UK is famous for his 2 stroke tuning. Remembering his name from when I was a teenager I googled, no e-mail so I called yesterday and got the man himself! He suggested the stage 3 tune, which for a TDR apparently keeps more midrange than with a TZR race tune. He mentioned carb jetting can stay standard and I'd just need to make sure the exhaust system I use is suited for a mid range tuned engine (Tinking probably a Cat house exhaust from Japan)
    So I'm now bidding on a used TDR250 engine so I can send off the barrels, power-valve assembly & head to Stan.

    Frame has some minor rust on it, so I'll probably POR15 it after a cleanup. I'd like to powder coat it, but such treatment isn't easy or inexpensive in Japan as it is elsewhere unfortunately.

    The body panels are in good condition but I'm not partial to the Lexus red metallic the previous owner has chosen. I'm leaning towards either metallic blue or perhaps a metallic white colour - with modern graphics carefully designed by a local friend who happens to be a tallented designer for Toshiba - who is also a biker (One I've been trying to entice to buy a bike!).
    The old TDR logos although nice, could certainly be improved. A crystal modern headlight will probably replace the original, but I like the idea of a powerful dipable HID too. These 20+ year old headlights are rubbish!

    I think I'll probably lose the Speedo with the new yokes, so will probably make a carbon fascia and mount some modern digital enduro style gauges in. I don't like the rev counter on the tank - That's a useless location for it. Wondering about maybe fitting a 60mm wide-band A/F gauge there - to help keep the engine in peak tune, but the only downside would be I could fit just one wide-band sensor to one of the chambers. Need more thought on this.

    Handlebars shall be changed for wider Renthals, quick MX spec. throttle, different indicators, seat re-trimmed with a better design & comfort by, Probolt stainless fasteners on the bodywork...

    It'll begin taking shape soon. No rush - as there's always other stuff to do along the way but I'm looking forward to having a pristine and fast TDR next year.
    Especially looking forward to mad 2 stroke umph at the higher rev range...

    A few pics as it looks before starting work. Doubt I'll get a chance to do anything much before Xmas if not end of winter... It'll be a runabout for now, meanwhile.

  6. #6
    Join Date
    Sep 2002
    Down by the river


    Cool promo vid. The TDR was definitely ahead of its time, about a decade before motards really took off.

  7. #7
    Join Date
    Mar 2012

    Default Bought a TDR250 2 Stroke Project Bike.

    Looks like a fun bike and project. Upgrades thus far sound great.
    Looks like a fun ride. I'm hoping to find something in that same vein myself.
    But until I sell the 2 current projects I've been working on it I'll have to wait .lol
    Getting to the Summit is Optional, Returning home is mandatory
    Life begins at 155mph

  8. #8
    Join Date
    May 2011


    Stan Stephens is a living legend! Just do what he says. Unfortunately Terry Shepard passed away recently There is going to be no one with their experience, knowledge and skills to replace them. Sad but true. Boyesen reeds and swarbrick pipes. Haha. Looks like you have a plan. Good luck.

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