Mattblfc8 Posted November 1, 2013 Share Posted November 1, 2013 My 2002 dt 125 seems to bog before it revs and doesn't like to idle on its own sometimes the revs drop and then the bike just cuts out is this a carb issue as I'm not to sure Link to comment Share on other sites More sharing options...
Moderator DirtyDT Posted November 1, 2013 Moderator Share Posted November 1, 2013 Was it running OK before? Does it bog all the way through the rev range or just at part throttle? When was the last time the jets were cleaned and the float reset? When was the last time the air filter was changed or oiled? When it revs does it idle high and slowly come down to idle and then cut out, unless you blip the throttle? Check for an air leak from the airbox to the carb by spraying some WD40 around the airbox to carb joints. Check the air filter. Check the carb jets and float height. Check for a crankcsae seal leaking. Link to comment Share on other sites More sharing options...
Mattblfc8 Posted November 1, 2013 Author Share Posted November 1, 2013 Bogs on just part throttle and I'm not sure only had the bike 2 weeks the air filter looks pretty new and yh it does rev high and then drop unless I rev it abit Link to comment Share on other sites More sharing options...
Moderator DirtyDT Posted November 1, 2013 Moderator Share Posted November 1, 2013 Sounds like a crankcase seal. I would clean the carb and check for air leaks first around where the carb and air filter join and the carb and head join. To do this, idle the bike and spray wd40 around all of the joins. Link to comment Share on other sites More sharing options...
Mattblfc8 Posted November 1, 2013 Author Share Posted November 1, 2013 Ok mate thanks I'll try that later is a crankcase seal an easy job to do Link to comment Share on other sites More sharing options...
dt502001 Posted November 1, 2013 Share Posted November 1, 2013 Also try a new spark plug. And no the crank seal is not a easy job if you have never done 1,should be lots of info about doing it though been discused many time here. Link to comment Share on other sites More sharing options...
Mattblfc8 Posted November 1, 2013 Author Share Posted November 1, 2013 Yh I've put a new spark plug in it could a dodgy battery cause some problems or not Link to comment Share on other sites More sharing options...
Moderator DirtyDT Posted November 1, 2013 Moderator Share Posted November 1, 2013 Yh I've put a new spark plug in it could a dodgy battery cause some problems or not I doubt it very much. Ok mate thanks I'll try that later is a crankcase seal an easy job to do It depends on your level of mechanical skills. It can be done in under and hour on some bikes for the left hand side - which is the one that tends to go more. Link to comment Share on other sites More sharing options...
Mattblfc8 Posted November 1, 2013 Author Share Posted November 1, 2013 Ok thanks is there a way to test to see if it's a dodgy seal before taking anything apart Link to comment Share on other sites More sharing options...
Moderator DirtyDT Posted November 1, 2013 Moderator Share Posted November 1, 2013 Always follow the main rule - When you have bike issues always look at the cheapest and easiest parts to replace first. The seals that can cause this are the crank seals. Normally there is one on each side of the crank. The right hand seal is normally immersed/semi immersed in engine oil so tends to last longer. The left hand seal, when it fails, lets air into the combustion area making the bike run lean and increases the risk of a seizure. The seals harden over time and stop doing their job. Bad idling can be down to the left hand crank seal. The problem can be worse when the engine is warm. The right hand seal change is normally only possible with an engine split. The seal would let in engine oil and this is burnt causing a more smoky 2 stroke and the bike will use more engine oil. The left hand seal can normally be removed with the engine in the bike. This is normally done by removing the left hand crank case cover, Removal of the stator, which exposes the seal. The seal can be popped out and a new one put in. A check for the left hand seal is to remove the left hand crank case, start the engine and to spray WD40 behind the stator plate. If this is leaking then the engine note changes. This sometimes doesn't work but often does. This is a general guide and you would need to check you bikes set up before doing this. In my TS250 thread - which is in the project section - shows me doing this to the TS. It is towards the end of that thread. Link to comment Share on other sites More sharing options...
Mattblfc8 Posted November 1, 2013 Author Share Posted November 1, 2013 Ok that's great thanks a lot I'll open it up tomorrow hope it's the left seal if any sounds a lot easier than the right but it does seem to be using abit more oil Link to comment Share on other sites More sharing options...
dt502001 Posted November 2, 2013 Share Posted November 2, 2013 Other than 2t oil the bike shouldn`t use any oil if the gear box oil is disapearing then you`ve found your problem the right seal is gone. Link to comment Share on other sites More sharing options...
Mattblfc8 Posted November 2, 2013 Author Share Posted November 2, 2013 Na the gear box oil hasnt dropped but now I can hold the throttle right open at it barely revs over 5k before dieing Link to comment Share on other sites More sharing options...
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