JonRisby Posted February 6, 2004 Share Posted February 6, 2004 Just bought a dt125r 1998 s reg and want to know if you can tweak the powervalve and/or change the exhuast to fully release its power Many thanks in advance J Link to comment Share on other sites More sharing options...
jimjam Posted February 6, 2004 Share Posted February 6, 2004 Just guessing here Jon but the restriction is usually in the exhaust via a sort of washer and in the carbs where you'll need bigger jets. Link to comment Share on other sites More sharing options...
JonRisby Posted February 6, 2004 Author Share Posted February 6, 2004 okey dokey. thanks for the fast reply... ill take a peak in the exhuast Link to comment Share on other sites More sharing options...
Admin Alex Posted February 6, 2004 Admin Share Posted February 6, 2004 Yep get a new exhaust, have a bike gear thingy so you can manually open the powervalve, (or fix tzr elecrric one), add some carbon reeds and bigger jets and away you go :shock: Link to comment Share on other sites More sharing options...
jimjam Posted February 6, 2004 Share Posted February 6, 2004 have a bike gear thingy Read Alexasigno's post Jon, Sounds like he really knows his onions!!! Link to comment Share on other sites More sharing options...
Admin Alex Posted February 6, 2004 Admin Share Posted February 6, 2004 hehehe you know the things on mountain bikes that pull the cable :oops: Link to comment Share on other sites More sharing options...
JonRisby Posted February 6, 2004 Author Share Posted February 6, 2004 DEP front pipe and end can! £200 sound a good price? Link to comment Share on other sites More sharing options...
Admin Alex Posted February 6, 2004 Admin Share Posted February 6, 2004 Yep, mozzy just brought the front pipe for £160! :shock: Link to comment Share on other sites More sharing options...
JonRisby Posted February 6, 2004 Author Share Posted February 6, 2004 wicked stuff... ill be ordering a full DEP system next week and also will i need to change the jets?? :)J Link to comment Share on other sites More sharing options...
liquidcooled Posted February 6, 2004 Share Posted February 6, 2004 that sounds ok for a full system. when you have the exhaust off look up the exhaust port and you'll see the power valve. turn it through about 180 degrees till the valve is flush with the top of the port. this will give full power. don't worry much about 'performance reeds' they're not worth it in my opinion. i've tried a few out. you'll need to upjet the mains for the exhaust. usually about two sizes for an exhaust and more for an airfilter. hope this helps. any more info needed then just ask mate :wink: Link to comment Share on other sites More sharing options...
mozzy Posted February 7, 2004 Share Posted February 7, 2004 right buddy follow these simple steps and your biike will be a beast change the exhaust dep is chrome and looks the beezkbeez although dtr125s pre 1999 wasnt restricted through the exhaust so ur front pipe should be alright the deps have a good performance enhancer then get the carb rejetted to a 240 they are 210 when standard then a set of boyussen racing reeds and obviously open the power valve and all dtrs from 91 til 98 were derestricted through i think it was the cdi the black box in the rubber mount under the fuel tank change that for one off a pre 91 and ul be sorted the pre 91 although looks different still works with all the stator coils and so on obviously mine being a g reg i dont need to upgarde my cdi unit let us know how u get on oh yes and for some better sound and very slight improvement on accelleration get a k&n filter Link to comment Share on other sites More sharing options...
mozzy Posted February 7, 2004 Share Posted February 7, 2004 john what colour is your bike and did u buy it from bristol my mate just sold a black s reg to a guy in cirencester for £1200 i think the one he sold had the old style power valve on it because the servo packed on the electric one Link to comment Share on other sites More sharing options...
JonRisby Posted February 7, 2004 Author Share Posted February 7, 2004 Its blue and white. i bought it from a old kiddy in cirencester :!: . 1 previous owner and i know the previous owner hes my mums best friends dad. Your close on the price £1100 down from £1200.... not bad really.. that covered the cost for sum new tires. :wink: p.s the bike has only done 10K and the engine is as smooth as a babys arse and i know the bike hasnt been ramped! Link to comment Share on other sites More sharing options...
Admin Alex Posted February 7, 2004 Admin Share Posted February 7, 2004 Yeah forgot about that mozzy, your right my dtr was 91on a h, and had the old cdi unit, as the newer ones dont rev as high, i think that was the difference :roll: Link to comment Share on other sites More sharing options...
Admin Alex Posted February 7, 2004 Admin Share Posted February 7, 2004 Well if your good with electronics this site tells you how to modify the cdi http://translate.google.com/translate?hl=e...DUTF-8%26sa%3DG CLick on the tuning on the left and Schaltplan CDI on the top, for the instructions. They also show you how to unrestrict etc.. GOod site, but the site has been translated via google so is quite funny but all seems pretty simple to follow 8) Link to comment Share on other sites More sharing options...
JonRisby Posted February 7, 2004 Author Share Posted February 7, 2004 Just been out for a ride... great weather for it! the bike maxes out at 65MPH, 8000RPM she will cruise happily at 55-58MPH. if i change the exhuast i think i will only reach 70-72MPH coz of the gearing and it redlines at 10500 also it will only rev to 8000RPM is this normal??? Thanks :)J Link to comment Share on other sites More sharing options...
Moderator YamaHead Posted February 7, 2004 Moderator Share Posted February 7, 2004 You'll might pick up that extra 2.5k on the clock after a new pipe & jetting is in place :wink: Link to comment Share on other sites More sharing options...
Admin Alex Posted February 7, 2004 Admin Share Posted February 7, 2004 Thats the cdi which is restricting the rpm, the old ones can go to around 12k, check the link and it has a wiring diagram of how to change it, or get an older cdi. Link to comment Share on other sites More sharing options...
mozzy Posted February 7, 2004 Share Posted February 7, 2004 mine revs upto 12k like i said earlier the modern cdi is restricted Link to comment Share on other sites More sharing options...
mozzy Posted February 7, 2004 Share Posted February 7, 2004 just give mine a thrashing today alex i got that dep front pipe for £135 in the end from ard racing components in walsall i have details if anyone needs em it is a very noticable difference to my old fresco{big one} i pulled away same as i usually would and the power valve seems to come in alot sooner and it was on the back wheel i was crapping myself but tried to control cause there was loads of people around it seems to have sacrificed a little bit of top end for a lot more bottom end which is fine for me a.r.d racing sell the complete dep system for £175 + p+p which is bloody reasonable Link to comment Share on other sites More sharing options...
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