Restricted power?



  • Hi. I am a proud owner of 1989 dtr125. As standard this model has no power valve servo. I have fixed the valve fully open, which makes it great fun at the top end of the gears. Question. What top speed would you expect a 14 stone guy to get out of it? I get 55mph max. Just wondering if this model has any other restrictors fitted. If not, then I'm happy to leave it as it is. Cheers



  • Heya. If I remember right, they have a pipe restriction as well and something else... but you're going to have to wait until one of the more um.. cough senior members, come around to confirm.



  • 70+ on that bike.



  • @Big-Col Hi - You should easily be getting 70mph+ on your bike. Hell I'm 18st of pure rock solid prime English beef and I could get 80-85mph top speed on my DTR!!!
    :grinning_face_with_smiling_eyes: :smiling_face_with_open_mouth_closed_eyes: :smiling_face_with_open_mouth_cold_sweat: :face_with_tears_of_joy: 🤣

    Awaits @declan comment??? 😉



  • Thanks guys. Nice to meet you. If anyone can give me a clue as to where the restrictor might be that would be great. Just to be clear, this is a 1989 model so suspect that there wont be any electronic restrictor of any kind fitted. Plan to take the head off to clean the power valve soon, as although it rotates freely, I wasn't able to get the 2 halves out previously. Think it's just stuck in there with carbon. Cheers



  • @Big-Col There's a whole sub-section on Derestricting under the Tuning section, there's even a comprehensive guide too - enjoy!!! 😉



  • Great, thanks. Will take a look.



  • @NINJA Should look at getting a 250 instead...



  • Funny you should say that. Getting a crm250 next (hopefully not a dirty word on this forum ;-). Like I said at the start, if it's already performing to its spec, then I'm happy to leave it as it is. Cheers



  • @Darty Once I've got my A1 aka big boy license, a big fat SuMo is on my wish list!!! :grinning_face_with_smiling_eyes: :grinning_face_with_smiling_eyes: :grinning_face_with_smiling_eyes:



  • @NINJA @Big-Col Haha,👌 nice one lads.



  • Just read the article about the potential exhaust restriction on the older model. Will wip it off later today and take a look. Either of you guys have an opinion as to weather a heavily gunked up power valve would make much difference to performance, bearing in mind that mine is fixed fully open? Cheers



  • @Big-Col If your PV is not set up correctly, damaged or faulty, then it will add restriction to your exhaust port.



  • Hi. Just removed the restrictor in the exhaust manifold 😁 it is like another bike. Don't think I'll need a 250 at this rate! Absolutely awesome. However, now I have a new challenge. Fuelling! Felt like I was running out of fuel at the top of 5th and 6th gear. Not much in the fuel tank but enough if think. Need to double check. Now thinking I may need a larger main jet in the carb? Will search around in the forum. Sure to be something here.



  • @Big-Col 210/240 main jet is standard on these engines for a DEP exhaust system



  • Thanks Calum. I took it out again this afternoon with more fuel in the tank. It happened again but then I remembered reading that I shouldn't be afraid to rev it hard at the top end. When keeping the revs high (8k+) it seems to run fine. Such good fun now, I can really appreciate what all the fuss is about these bikes. And that's coming from a guy who has a 959 Ducati! (Without wishing to sound like a t*oser)



  • @Big-Col no worries I've got a 1200 Multistrada to go with my DT200WR and TDR Belgarda



  • Nice bikes 👍



  • And I've got a Railegh Maverick which is savage.



  • @Calum That's not as bad arse as my custom DMR!!! :grinning_face_with_smiling_eyes: :grinning_face_with_smiling_eyes: :grinning_face_with_smiling_eyes:


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