Brian Sussex has put together an awesome page on the TT. It gives the key specs on the bike and also provides usefull pointers as to which parts are available and what modifications to make. He is also one of the owner of a discussion group on the topic.

• TT-R 250 FAQ [cached]
   
• TTR 250 Yahoo Group

Modifications

TT-R users tend to complain about the lack of power of the beast. But then again it seems to be a common trait between bike owners. Not surprinsingly most of the mods tend to palliate this weakness.

• Let it breathe
  

  The airbox snorkel comes out easily and immediately offers better grunt. We then tested the bike with the side cover off the airbox to see if it was still starving for air. It was, so we drilled a serie of 12mm holes in the lid of the airbox to better aspirate the carby. Unclutter the Airbox and Boot We weren't quite sure what the chamber off the top of the airbox boot achieved. But, because the American model doesn't has it and testing proved that it offered no performance advantage, we figured it helps reduce induction noise. Removing it helps unclutter access to the carburetor. Plug the hole left with a piece of old inner tube and silicon adhesive. The metal bracing inside the airbox is also absent on the american model and again we assumed it aims to keep the resonance and therefore noise down. Removing it gives better access to the air filter. Fill the holes left by the pop-up rivets to maintain the airbox waterproof.

  
   
• Use a brake snake to tie up the lever
  

  Both brake and gear levers on the tt-r need to be secured for racing. they aren't as robust as we'd loke. The brake lever comes with a pre-drilled hole for a brake snake, but the gear lever doesn't. we put a white brothers brake snake on both levers, leading them as far forward as possible to minimize the risk of snagging on trail schrapnel. the best bet is still to drill a hole in the mounting lug of the frame and secure them there on both side. make sure you leave enough slack in the snakes.

  
   
• Bridge the sidestand safety switch
  

  The tt-r has an electrical circuit with an emphasis on safety for the average punter who likes to ride around with the sidestand down or start the bike in gear with full trhottle. if you simply unplug the wiring runnin gto the sidestand safety switch, the bike will start. but as soon as you click into gear it will stall because the electrical circuits thinks the sidestand is down. it's imperative to bridge the wire as shown in the pic to ensure the circuit remains complete. the black wire running to the removed stand (with blue plug on the end) can then be removed altogether.

  
   
• The neutral switch is vulnerable to rocks
  

  The neutral safety switch is an earth wire (shown under the cases here) which prevents the bike from startgin in gear. one look at the thing and you will realize how vulnerable it is to getting snagged on rocks or sticks. Remove the wire and earth the plug end. we earthed it to the finned regulator. you will need to trace the wire (it is the only single blue wire going up inot the rubber plug housing), disconnect it, and then add a small lenght of wire to earth it.

  
   
• Modify or replace the muffler
  The stock muffler unit is very restrictive and prevents your engine from breathing properly. The simplest option is probably to replace it by one of the many after markets mufflers available. However you can also modify the original unit according to the following schematics.
  

  The schematic and picture bellow are a view of the standard muffler. Arrows and legend aim at explaining how the exhaust gases flow through the unit. Consider the stock muffler divided into three main sections or chambers:
  

  · The first section coming from the engine is identified by a question mark on the schematic as we do not know how this part of the muffler is designed. This section is the first one traversed by the exhaust gases.
  · The second section will be called the middle section. Gases coming from the first section bypass this section by travelling through a first set of pipes leading to the third and last section.
  · The third section, or the tail section, is where gases coming from the first section come first. Gases are then redirected back to the second section from where they finally find their way out of the muffler.

  To resume things, gases travel throught he first section to the third section, then back to the second section before finally being expulsed. The objective of the mod described here is to make things a little bit more straight forward by letting the gas exit the muffled from the first section.
  
  

  	section view of the muffler
  	The original muffler include 5 pipes. The 2 pipes on the left carry the gases from the 1st to the 3rd section, they are the ones that are going to be extended. The top pipe links the 2nd section to the outside. The 2 pipes at the bottom right carry the gases from the 3rd section back to the 2nd section.

  This schematic shows the muffler after modification. The operation basically consist of extending the set of pipes that were originally connecting the first section to the third section, to directly let the gases flow outside the muffler. In order to do so: remove the silver plate riveted to the end part of the muffler cut this section 3cm after the first welding identify the 2 pipes coming from the first section and drill out the 3 other ones weld two extension pipes to the two pipes remaining drill two holes in the third section of the exhaust to let the tow pipes out and fill the spaces left Weld the cut section back and re-rivet the silver plate

  
   

Specifications

The 250 TT-R originally came in two flavors, the open enduro and the raid. Both bikes had the same specs excepted for a larger gas tank (16l) and a larger optic on the Raid. The bike was redesigned 1999 abandoning its original white color for a blue color scheme. Suspension were upgraded and the digital speedometer replaced by a regular unit.

A picture of a stock 250 TT-R 2000