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

Hi Gary, try here http://www.yamahait.com.au/forum/index.php/board,29.0.html

try these guys I get all my genuine spares from here http://www.granbymotors.co.uk/spares.php?lnk=Yamaha

I think you know the answer , in the short term bleed it . For a proper service strip and replace seals and fluid , possibly replace brake hose with braided . BobC

If you get stuck Andy at is a good man for older Yams he is my supplier for DT carb bits

hello bob- not sure wot u mean by needle valve? Is ur bike stock all round bob? i m also using br8es- wot does the light brown colour indicate about the way bike is running? i m preety sure u said u hav disconected auto-lube. is that why u hav had 2 change jetting from standard? Hi RR, the needle valve set part no 2MA-14107-28 controls the supply and level of the petrol into the carb, if they are worn or old or level not adjusted correctly the mixture can be affected, worth replacing before jetting the carb . Yes I did up the pilot jet after removing the autolube , otherwise the bike is stock minus snorkel.I used to run BR9ES which is the stock plug , but generally I am not revving the bike hard and the 8 plug runs better. Here is a link to a plug diagnostic guide http://www.ngksparkplugs.com/tech_support/spark_plugs/faqs/faqread.asp Bob

"studders" I read this as 4stroking ? in which case there is every chance it is running rich , the plug colour should give you a good guide . If it was rejetted for the exhaust they may have overdone the jetting / needle height . Bob ps rr90 to reply to your pm , i had a similar problem to misfits, after changing needle valve then crank seals I was able to get closer to a good setting , slightly out at the moment cos its so cold .currently running 35 pilot 150 main middle clip , plug BR8ES - colour light brown after a thrash

Hi, the powervalve can need cleaning to remove carbon etc., here is a useful set of pics , watch out which way you replace the valve , they can go in 180 degrees out . This site also has manuals http://www.dtr125.net/videohtml/ypvs/powervalve.htm Bob-C

I have to agree with Cynic, I have the same bike a 88DT200r . At this age there is 99% chance the crank seals are leaking . If you don't fix them 1st you will never get the mixture right . Watch out for pattern seals , they are cheaper but imho not up to the job , get yamaha ones. There is a fair bit of info on here but you need to post a few times to get access to all sections www.yamahait.com.au

Yes both the crank seals can be changed without splitting . For the stator side you will need a flywheel puller size 27x1 LEFT HAND THREAD , it's a quick job . Bob C

Yes both the crank seals can be changed without splitting . For the stator side you will need a flywheel puller size 27x1 LEFT HAND THREAD , it's a quick job . Bob C