lee jones Posted September 17, 2008 Share Posted September 17, 2008 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 Link to comment Share on other sites More sharing options...
Moderator Airhead Posted September 18, 2008 Moderator Share Posted September 18, 2008 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) Link to comment Share on other sites More sharing options...
lee jones Posted September 18, 2008 Author Share Posted September 18, 2008 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 Link to comment Share on other sites More sharing options...
Moderator Airhead Posted September 18, 2008 Moderator Share Posted September 18, 2008 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 Link to comment Share on other sites More sharing options...
Twin Shock Posted September 18, 2008 Share Posted September 18, 2008 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. Link to comment Share on other sites More sharing options...
lee jones Posted September 19, 2008 Author Share Posted September 19, 2008 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 Link to comment Share on other sites More sharing options...
Moderator Cynic Posted September 19, 2008 Moderator Share Posted September 19, 2008 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. Link to comment Share on other sites More sharing options...
Twin Shock Posted September 21, 2008 Share Posted September 21, 2008 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. Link to comment Share on other sites More sharing options...
racerd Posted September 22, 2008 Share Posted September 22, 2008 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 Link to comment Share on other sites More sharing options...
PPCLI-jim Posted November 8, 2008 Share Posted November 8, 2008 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 Link to comment Share on other sites More sharing options...
racerd Posted January 21, 2009 Share Posted January 21, 2009 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 Link to comment Share on other sites More sharing options...
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