hi i started this project nearly a year ago now. we brought the dt125r in pieces.
After rebuilding the engine, changing the power valve, new oil seals, and some other small things. The bike didnt run. We then came to the conclusion that there was something wrong with the carb, as there was no fuel getting into the cylinder. But when we put fuel down the hole where the carb connects to it ran fine until the fuel ran out. Because of this we brought a working second hand carb. And now nothink has changed.
Sure youve put the fuel pipe on the right one and not on the carb heater pipes?
fuel pipe stub is on left hand side of carb (sitting on bike) and not the two pipe stubs that sit side by side.
Depending on carb you might not have those AFAK only the flatslide carbs have them.
Other things to check is youve actually fitted the boost bottle to the inlet rubber? sounds obvious but had me and a mate stumped as to why his bike didnt start.
Checked for a spark?
Could also be a split in the inlet rubber , have you opened up the new carb? it possible that the float valve is stuck closed on both.
Andy
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Anyone need to know info on dt's? just give me a shout and ill be glad to help on derestricting and servicing.
funny this i to am having a simular problem it is a pig to start when i get it running it does run and idle but it bogs bown when throttle is open and wont rev past 6-7 thou i have put the powervalve servo with tzr control box ( gives power in different places) new fuel tap, plug stripped and cleaned carb.......
when you rebuilt yours did you have it rebored (oversized) as i beleive it may be the source of my probs ( i.e i havent rebored yet)
apexer0, i had a very similar problem to this. My airfilter was wet and really dirty, a new one fixed the problem. It could also be your mixture screw in the carb.
ToM Make sure all the carb settings are correct, follow the manual (if you got one) Make sure the slide needle is set in the correct position and make sure your reeds are not stuck down and are also adjust to the correct distance apart.
My tank has 2 outlets from the tank. 1 standard for everyday running give about 80 miles running. 2nd being the reserve giving about 10 miles used for finding that petrol station that is 15 miles away!
dtrworld2 wrote: apexer0, i had a very similar problem to this. My airfilter was wet and really dirty, a new one fixed the problem. It could also be your mixture screw in the carb.
have fitted a new lightly oiled air filter already, had to drill out the old mixture screw retap and buy a new screw(12 quid), set the power valve up by the book, new plug, stripped blownt the carb right through with compressed air rebuilt and setup by the book,
so when it starts it will run on choke and off seems to be a bit like gasping for air or fuel when you rev it from idle it does pick up and then revs fine upto 6-7 thou then it seems as if its misfiring i.e picking up then dying i know its not the spark as i have a tester that lets you see it firing it ,also smokes a lot when it is doin this
kinda sorted it plug lead was breaking down and the power valve (tzr)control box( i have been unable to find the three wire servo) is placing the valve in just the wrong place
compression could be better but it will do at the mo will get it rebored when i strip engine down to do noisey box brgs
