Anditover Posted May 16, 2014 Share Posted May 16, 2014 For those of you after a bit more speed, I just did a winter spruce up on the DT: New head bearing, fresh fork oil, fresh brake pads and fluid, and then a new genuine air filter (they're washable but mine looked a bit tired), and a new chain and sprocket kit. Since fitting the last 2, there is a noticeable difference. The engine note is more crackley, tickover is steadier, and it feels more willing. The other morning I cracked open the throttle in 1st to get past a car turning right, and it lifted the front wheel in both 1st and 2nd gear. Not by much, just enough for me to feel the wheel touch down twice, but I reckon renewing the transmission got me at least 2 bhp, and swapping the filter got me useful torque everywhere. My old chain and sprockets actually looked fine, but when you got the old chain off and compared tight links, and how well it flowed, you could see it was power sapping. I used a genuine kit, but it was made by DID (with O rings and split link). Hope that helps. Link to comment Share on other sites More sharing options...
blackhat250 Posted May 17, 2014 Share Posted May 17, 2014 The TDR was a thrill, but I sold it after 18 months from new. Too buzzy and a one trick pony. Hee " can"t wait to see Cynic answer that ,, . Your right about the Zed , heavy bastewrt, The H2 with brembo brakes firm rear shocks and Avon Roadriders , would surprize you Link to comment Share on other sites More sharing options...
Sheps18 Posted November 3, 2014 Share Posted November 3, 2014 90mph haha dont think so my 660c does 110mph tops so ure almost asking the imposible unles u want to do big bore kits and bigger carb messing with the gearing u will be lucky to get 80mph and thats geting sports exhaust replaceing the air filter uping the jet sizes in the long run its not worth the hastle you might as well do ure full license and get a biger bike like i did sorry to burst ure bubble but to get 70mph out of it aint bad at all IVE GOT A 06 DT125R IT DOSE 73 MAXED OUT STANDARD, IVE HERD BY ALOT OF PPL YOU CAN GET 90 OUT OF THEM HOW IS THAT POSSIBLE ? AND WHAT WAYS CAN I MAKE IT ALOT FASTER, I ALSO SEEM TO LOOSE POWER IN GEAR 5 WHATS THIS ALL ABOUT ??? CAN SUM1 HELP ME OUT ON THIS PLEASE. BE MOST APPRECIATED. THX. Dom19 barwell1992 Barwell you can shut up my dt125r tops out at 93mph and ur S**tty little 660cc hunk of S**t will not top out at 110mph you have got it restricted you imbecile you obvs dont know your bikes so i would not listen to you Thank you get back to me. Dom19 you will have to clean your air filter and your carb because there will most probably be dirt in there restricted the air flow. Link to comment Share on other sites More sharing options...
Moderator DirtyDT Posted November 4, 2014 Moderator Share Posted November 4, 2014 Oh dear! It looks like DTR's are so fast now that they are warping time. Maybe Richard Branson should be looking for one to power his space missions. 1 Link to comment Share on other sites More sharing options...
slice Posted November 4, 2014 Share Posted November 4, 2014 Well DT he certainly has a short enough fuse !! (man above I mean) 1 Link to comment Share on other sites More sharing options...
Moderator Airhead Posted November 4, 2014 Moderator Share Posted November 4, 2014 just think how fast they could have been if they hadnt offered the aerodynamics of a barn door 2 Link to comment Share on other sites More sharing options...
Moderator DirtyDT Posted November 5, 2014 Moderator Share Posted November 5, 2014 Yeh, but 300 MPH with the speedo mod and no airbox is fast enough for a 125. Link to comment Share on other sites More sharing options...
blackhat250 Posted November 5, 2014 Share Posted November 5, 2014 Remember C.B.D. gents , he shocked a few 400"s with his tdr125[180cc] Link to comment Share on other sites More sharing options...
Anditover Posted May 10, 2015 Share Posted May 10, 2015 Just like to add, since my last post, I've had the DT dynoed. I was curious to see what was really going on in mine, and to make sure that when it was revving hard, it also wasn't running lean. Unfortunately I can't seem to add an attachment to show the graph, but I am happy to email it if people are interested. It was done on Tuesday 5th of May, barometric pressure was about 989mb, in other words pretty awful. The tuners said it was so bad it was probably robbing me of a whole horsepower. All figures are RWBHP. 5,000rpm: 7.25bhp 7.5 ft/lb torque 6.000rpm: 9.50 8.5 7,000rpm: 14.50 10.7 8,000rpm: 14.50 9.5 between 7 and 8,000, the power dipped to 13.5bhp as the torque dropped from its peak. 9.000rpm: 16bhp 9.5ft/lb 10,000rpm: 13bhp 7.0ft/lb peak output was 16.98 at 9,500rpm, and 17.58 on two different runs, peak torque was 10.73 at 7,000 rpm. Stock pipe, airbox etc. Only the reed switch moved out of the way. A rattle in the front expansion chamber, would indicate that one of the restriction crescents has dropped off. Result also indicated that the airbox, carb manifold and silencer is NOT restricted by the factory. I don't know why no one else has done it before, I can be emailed on [email protected] if anyone would like to see the full report. Estimated top speed ( with wheel slip from the knoblies in the dyno was 75mph). Link to comment Share on other sites More sharing options...
Moderator Cynic Posted May 11, 2015 Moderator Share Posted May 11, 2015 Wow. Brave man putting a 2stroke on a dyno. Good info though. Link to comment Share on other sites More sharing options...
Anditover Posted May 11, 2015 Share Posted May 11, 2015 I used a tuning shop called Dyno Tech, they're experienced (that's code for middle aged) and support alot of teams in BSB and enduros. Fuelling wise the DT, on factory settings, is lean at tickover (where no harm could be done), spot on in the midrange, and reassuringly rich at full throttle. That was part of the reason I took it in, having found that on some days it got its second wind at 8,000+ rpm, I wanted to be sure it wasn't running lean (which would crispen up the throttle response before crispening the piston). I was quite prepared to rejet, but the advice was stay stock. Also, the well intended advice to cut off the rubber protrusion from the carb gasket to the reed block, would appear to be misguided. I took mine off, measured the diameter, and concluded that it was the same as the exit from the carb, and the point of the protrusion was not to restrict the fuel mix, but to guide it at a constant velocity directly at the reeds. Widening the route at that point would result in reducing pressure and velocity of the fuel/air mix. Probably not helping performance. 1 Link to comment Share on other sites More sharing options...
Moderator Airhead Posted May 11, 2015 Moderator Share Posted May 11, 2015 have to agree, that's why I did this to mine rather than chop off the whole lot...a likeness to some YZ Yamaha intakes another favourit so called tuning mod often seen suggested is to remove the intake snorkel...it sounds horrid when you do, so here again I did something different and fitted a set of boyesen reeds I don't believe that any of these mods did any harm, however I never dyno'd it so cant be surre of any improvement or not Link to comment Share on other sites More sharing options...
blackhat250 Posted May 11, 2015 Share Posted May 11, 2015 Is that your oil feed on the intake paul /? . Impressive figures andover" better than the old DT175 , [ TWINSHOCK] , Lean that main jet a tad and it would fly,,, Link to comment Share on other sites More sharing options...
Anditover Posted May 12, 2015 Share Posted May 12, 2015 Thanks, I just thought it was about time someone got some base figures, as well as checking on carburation to see if part of the restriction was over jetting or whatever. The Lambda sensor basically told us that whilst yes, it is a tad rich at the top end, it's the sort of rich that keeps you out of trouble if you rag it on a chilly morning. I would love to post the graphs, but my membership level doesn't let me post attachments. Whilst at the tuners, we compared runs with other DTs. There was one which produced 19bhp, a 1990 bike if I remember. It had a race exhaust, no air filter (brave), and 3, repeat 3 bhp up to about 6,500 rpm, then the graph went up at about 60°. Utterly horrible to ride, and likely to spit you off if you hit the power band mid corner, no other details, but presumably the bike has expired by now. Nice work on the rubber manifold Airhead, it fooled me for a second into thinking it was a factory version, perfect symmetry. The next step is to borrow a bendy camera from a friendly mechanic I know, and have a look down the exhaust header. I feel sure that at least one restriction at the mouth of the expansion chamber has fallen off, but if I can get a good look to confirm, then I think we'll have cracked how to derestrict a standard bike without blowing a stack on pipes, jetting and hi-flow air filters. And more importantly, keeping the reliability. 1 Link to comment Share on other sites More sharing options...
Moderator DirtyDT Posted May 12, 2015 Moderator Share Posted May 12, 2015 I would love to post the graphs, but my membership level doesn't let me post attachments. All members can post pictures in threads. It may be that it is not in the correct format. They may need to be picture files so; JPG etc. Link to comment Share on other sites More sharing options...
Anditover Posted May 12, 2015 Share Posted May 12, 2015 At the bottom of the page there is no icon indicating "attachment". After a row of various social media choices, all I can see is an email envelope, a printer option, and a download icon. When I tried to post a photo in the gallery, it said the photo exceeded the maximum size, with no option to resize. So I'm stuck with text. I even added the graph to my clipboard, but the forum doesn't allow clipboard items to be inserted. Anyway, if a moderator wants to email me at the above address, I'm happy to put the data out there for reference. Link to comment Share on other sites More sharing options...
Moderator DirtyDT Posted May 12, 2015 Moderator Share Posted May 12, 2015 Have a look here You can resize using the paint programme I think. Link to comment Share on other sites More sharing options...
Anditover Posted May 12, 2015 Share Posted May 12, 2015 I'm using an android phone. None of the windows menu items are available. Link to comment Share on other sites More sharing options...
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