hi all this is my first post,have just bought an old air cooled dt125 and the problem is when you rev it up or ride it there is no power will rev so much the sound as if there is a rev limiter,just spluttering and not reving up,have changed spark plug,tied a different ht lead and cap,not sure if it a weak spark theres compression and the carb has been checked and is all fine,it wont die but will not rev up any more so have to change gear will only rev about 2 seconds in each gear before you have to change as there is no more puff just like a rev limiter,i quite sure it must be electrical any suggestion would be greatfully appriciated

Hi Lee and welcome to the forum.

Youve just bought it so you dont know the history

Strip down the carb and thoroughly clean all jets

Check and set the float height

De coke, especially around the exhaust port

Check the air filter, does it need cleaning and re oiling? (Thats if its still the original foam type)

cheers for fast reply mate,carb seems to fine had my mate check the mixture and stripped it all,have not done anything to the exhaust yet,the air filter has the pipe missing from the carb to the air box,my bike looks very similar to yours,will check the things you said tommorrow,could the bike run funny with the air box not connected,thanks again for fast reply

cheers for fast reply mate,carb seems to fine had my mate check the mixture and stripped it all,have not done anything to the exhaust yet,the air filter has the pipe missing from the carb to the air box,my bike looks very similar to yours,will check the things you said tommorrow,could the bike run funny with the air box not connected,thanks again for fast reply

Well the answer is yes really, it means your not using your air filter which isnt a good ida really, having said that, it might not be that...But you really should be using your air filter, Ive seen those carb to airbox connectors on ebay, i'll look out for one and give you a shout

hi all this is my first post,have just bought an old air cooled dt125 and the problem is when you rev it up or ride it there is no power will rev so much the sound as if there is a rev limiter,just spluttering and not reving up,have changed spark plug,tied a different ht lead and cap,not sure if it a weak spark theres compression and the carb has been checked and is all fine,it wont die but will not rev up any more so have to change gear will only rev about 2 seconds in each gear before you have to change as there is no more puff just like a rev limiter,i quite sure it must be electrical any suggestion would be greatfully appriciated

I need to know the year model of your bike and I can help you.

its now a off road bike but at a guess and looking over the internet i'd say around 1980,its very similar to the green one above your last post its not mono shock its the same as the one above,it has the same vents on the front mud gaurd as the one above same,same side plastics,when i search when i search 1980 -82 most of the pics it finds are the same as mine it has cdi and not points,the coil has a single wire going to it,theres a black and white wire from the cdi unit not being used but from what i searched it might be the kill switch but i dont have one,it just wont rev properly it wont die but just sounds like a rev limiter,cheers for the help will try and get a photo uploaded

Some of these had 2 speed cdi units, sounds daft i know but mine has one. There is a low and high speed circuit and if the high speed circuit is not connected then it will not rev much over 5000 rpm. Had the self same thing when i bought mine years back.

hi all this is my first post,have just bought an old air cooled dt125 and the problem is when you rev it up or ride it there is no power will rev so much the sound as if there is a rev limiter,just spluttering and not reving up,have changed spark plug,tied a different ht lead and cap,not sure if it a weak spark theres compression and the carb has been checked and is all fine,it wont die but will not rev up any more so have to change gear will only rev about 2 seconds in each gear before you have to change as there is no more puff just like a rev limiter,i quite sure it must be electrical any suggestion would be greatfully appriciated

Lee, I would go back the the carburator and replace the "O" Ring on the Neddle jet (main nozzle) this little "O" Ring is very important and must be in good condition. The bike will not rev if the "O" RING is not sealing. This is a easy start to finding your problem.

in the photo below shows the rubber o ring this must be put

back on and a touch oil smeared on the rubber o ring

have loads of photos on a assembly of a vm round slide carb

on my forum

whats the forum? i have just gotten a 1980 DT 125 and im sure its the carba but would like the specs on a rebuild of it ..

thanks loads jimbo

whats the forum? i have just gotten a 1980 DT 125 and im sure its the carba but would like the specs on a rebuild of it ..

thanks loads jimbo

http://rdcchatforum.forumcircle.com/index.php