dtr_125 Posted February 5, 2007 Share Posted February 5, 2007 dtr125 with a dep silencer, when i got it last october up till the topic about starting problems last month it would do around 70 easily and at a push 80,but since then when it hits 60 the revs jsut stop even downhill with the wind wont go above 60 and thts in 5th still dosnt go faster in 6th jsut lower revs ne1 hav any ideas? cheers Link to comment Share on other sites More sharing options...
Willenium Posted February 5, 2007 Share Posted February 5, 2007 When was it last rebuilt? Being that you take it to 80mph it's getting pretty abused so it might be time for a new piston and possibly a rebore. Don't forget to decoke it too. Link to comment Share on other sites More sharing options...
dtr_125 Posted February 6, 2007 Author Share Posted February 6, 2007 i dont usually abuse it only got it to 80 twice to c whts it could do usually stay around 65 but its been built from different years so the clocks say 6000miles but engine might have done alot more, im not very mecanically minded is a rebuild sumert you can do yourself or best in the shop? Link to comment Share on other sites More sharing options...
Willenium Posted February 7, 2007 Share Posted February 7, 2007 It is something that can be done yourself but if you're not sure about it then I'd leave it to a mechanic to do. Easily goes wrong as I found out. They'll be able to check the condition of the bore and tell you whether it needs to be rebored or not. Hopefully it will be alright and you will just get away with a piston kit and a decoke. Decoke it properly though or it will just clog up again. You need to clean all the deposits from inside the cylinder head and finish it with metal polish so that it has a shiny surface (allows better gas flow for improved performance and also slows down the coking up). Remove powervalve and the same applies. Scrub it clean and polish it. Running in process takes about 300 miles. After you've covered the first 200 miles you can take it past the midrange and into the powerband just for a quick squirt to clear any buildup, not higher than 7k though and don't keep it there (You literally need 1-2 seconds). Link to comment Share on other sites More sharing options...
dtr_125 Posted February 13, 2007 Author Share Posted February 13, 2007 i have cleaned out the exhausts and also cleaned the spark plug and set the oil pump as it was giving to much oil thought and the accelaration has improved but top end still at around 58-60 then as soon as it hits 60 the revs just bog and die, i tryed lookin up the exhaust port to see how the powervalve was set but couldnt see it, the pistion seemed really shiney on the surface didnt look clogged, how can you tell is it is coked or not? cheers Link to comment Share on other sites More sharing options...
Willenium Posted February 14, 2007 Share Posted February 14, 2007 Have you tried buying a brand new spark plug? Sometimes they get a bit dodgy after some use. Check your HT cap is in good working order too. Have you had the carb out for a clean at all? Maybe there's some kind of blockage in there. Decokes are quite beneficial, especially if you ride around at low speeds frequently. Wont necessarily be if, but when. Link to comment Share on other sites More sharing options...
maselbac Posted April 6, 2007 Share Posted April 6, 2007 you want top end. remove the dep and put back the original front pipe...... the dep pipe for dtr's looks very similar to the fmf gnarley pipe which is designed to give maximum power in low to mid rev range, ideal for offroad conditions but it wont get you doing 80-90mph. take my yz for example.... it would piss over most road bikes to 40-50mph but id be flat out in 6th not long after. i have aftermarket pipes, 13tooth front sprocket and a 52tooth rear. set up for acceleration (wheelies in every gear) if i remember rightly, standard final drive on a dtr is 15t front and 57t rear, if you gonna keep the dep change the front sprocket to 16t or rear to 55t for more top end..... Link to comment Share on other sites More sharing options...
maselbac Posted April 6, 2007 Share Posted April 6, 2007 if you cant see your powervalve its fixed open permanantly ( deristricted ) Link to comment Share on other sites More sharing options...
Willenium Posted April 7, 2007 Share Posted April 7, 2007 Wrong and wrong. The final drive on a DT is 16/55 for the older DTR and 16/57 on the later DTRs. 17-18 teeth up front is alright as long as you're quite light. The powervalve is not necessarily derestricted just because it's the static unit. They use a pin to hold it partially closed which helped them keep it within the emission limits and it also limits to power to make the bike learner legal. You can remove the pin and spin the power into it's open position but you'll lose bottom end power so what people normally do is fiddle with the valve position until they're happy and redrill another hole to stick the pin into and thus hold the valve in position. What you want is a fairly even balance of low and top end power. With the later models they eliminated this problem with a servo unit. Link to comment Share on other sites More sharing options...
maselbac Posted April 7, 2007 Share Posted April 7, 2007 he said he cant see the pv in the exhaust port. that means its fixed open. if it wasnt fixed open he would be able to see it, even if it wasnt fully open you would still see some of the powervalve. the standard final drive on my 92 dtr was 15t-57t (70mph easy). i bought the bike brand new from a dealer so nothing had been changed. but im still wrong eh.... Link to comment Share on other sites More sharing options...
dtr_125 Posted May 8, 2007 Author Share Posted May 8, 2007 long time since last post but thanks for help, i took top end off and piston rings were nackered so changed them and polished all the carbon off the head and piston and also put a 17 teeth sprocket on front and now it is better then its ever been will reach 70-75 and will go off the clock downhills not even red lineing no problem. before it wouldnt hit 55 even downhills then would cut out (rings i think loosing the compression) just run it in and is sweet as a nut thanks Link to comment Share on other sites More sharing options...
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