bob-c

It will be a bit of a job to add a battery if the bike is not designed for one , run it without the bulbs it will be ok . Bob

Power valves can be fitted 180 degrees out , it may have been taken out for cleaning and replaced wrong . Worth giving it a clean and checking , if it is gummed up it will not want to turn , it does require a good battery as well .

you should find the info in here, the 200 is the same as 125 but the wiring diagram is slightly different http://www.dtr125.net/workshop-manualf.htm

here you are , probably the best forum for all Yamaha dirt bikes, I think you have to make a few posts to access all parts of the forum BobC http://www.yamahait.com.au/forum/index.php/board,29.0.html

Dead Right It is very tempting to mess with porting and exhausts , unless you are a skilled tuner you are more likely to lose power. Your efforts are best kept to keeping the bike in good order. Once you have done the standard de-restricting of a dt125 ,the next step is probably a pukka exhaust system like a DEP . After that I reckon there is no substitute for a bigger bike !

First thing is to check if you are jetted ok now, the colour of the plug gives a rough idea, ideal is mid brown http://www.dansmc.com/sparkplugs1.htm If you want to be more specific e.g. if you think it is out at full throttle , then a plug chop will tell you , but it costs you a couple of new plugs No point re-jetting just for the sake of it , http://www.kawasakimotorcycle.org/forum/kawasaki-motocross-offroad/17227-spankeys-jetting-guide-info-2-stroke-riders-must-have.html http://www.thumpertalk.com/forum/showthread.php?t=538197 Bob

Check oil level , if not overfilled then it is likely to be a worn crankshaft seal , you may as well do both sides . OEM Yamaha ones are expensive but better than pattern ones. Bob

Surely with it pegged open you are only getting the same power as when the pv operates normally and you thrash it ? except you have the disadvantage of no power low down before you hit the power band, I cannot see how this makes the bike faster - or am I missing something ? Bob

To answer the original query, yes change your plug to the correct one . An alternative to the BR9ES is the BR8ES , if you are fouling plugs because of slow running you could try an Iridium plug , they resist fouling so I am told by trials riders, I run an NGK BR8EIX as I ride tight trails with very little full revs and have no problem with plug fouling .

I bought pattern ones from Portugal off ebay for my DT and they lasted all of 3 months before disintegrating totally , OK so there is a lot of sun here !! BobC

And don't tell them about spell checkers either

Exactly what do you mean by studder ? is this on a fixed throttle opening or when accelerating ? what size jets and needle position ? Bob

Primary drive , thats the one on the end of the crank ? RH thread . I was once told the only LH thread on DT's is the flywheel and one of the mirrors ! I have never found any other . Bob

Lee, I have been researching pistons this week , my DT200 is ready for a rebore. Pattern ones like Matika (Taiwan )are cheap but seem to be a risk . I have decided to pay more and go for either OEM or Wossner , the Wossner are forged and get good reviews the site is in German /English and gives prices for pistons and piston kits , there are plenty of dealers in UK I would not like to ride thinking the piston might give up on me . Bob

I have sent you a PM