i have a 1989 dt125r which has a dep exhaust system,performance reeds ,working power valve and when it hits the powerband it goes very well,but when at very low revs it will not tickover and will die when opening the throttle,from about 3000rpm it is fine

i stripped and cleaned the carb and found nothing amiss,in fact it was clean so it is not blocked jets ,the main jet is 210 ,when starting the bike does need choke ,but when it has been run for a couple of minutes it will start fine but you have to catch it on the throttle to get it to rev

ps i cant give the bike max revs yet due to running in and the engine is turning freely

any help would be appreciated

grt rid of the electric powervalve it may be smoother but its also a pain in the arse they are also more fun without it ive had 3 dt125r,s and one had operational powervalve and was crap the other two were great fun just peg it fully open and piss your mates off

the powervalve is not the problem,the bike is a right bitch to start,even when it has been started it will only start on choke unless warmed up fully.

if the revs drop below 2500 rpm it will die,seems to be running weak at low revs,today the bike wouldnt start even by bump starting,screwed out the idle mixture screw and it started on the kick start! rode it around the garage a couple of times and it died again,got it started by bump starting and it ran for a minuite then died.

below 2500 it will not respond to the throttle and will not tickover

Had a similar prob wit my dt, the petrol pipes wer blocked and not allowing enough petrol into the carb. cleaned them and it has been fine since.

fitted new pipe over a week ago with a genuine yamaha part,bike had originaly aclear plastic pipe which i chucked away,i made a piece of pipe up to get it going but no change,the last owner had the same problem :cry:

did you check the pilot jet in it? could be bunged up! make sure its at the right setting also. standard setting for the air screw is 1 1/2 turns out. check the battery is charged and not defective. check the plug in it is ok and the correct one(even if if it looks ok they can be dud so try another out). check for any air leaks in the intake! check the air filter(it may be clogged up). float heights may be worth checking also :wink: a few things for you to try/check over. let us know how you get on. not really an expert on dt's but these are fairly general things

the powervalve is not the problem,the bike is a right bitch to start,even when it has been started it will only start on choke unless warmed up fully.

if the revs drop below 2500 rpm it will die,seems to be running weak at low revs,today the bike wouldnt start even by bump starting,screwed out the idle mixture screw and it started on the kick start! rode it around the garage a couple of times and it died again,got it started by bump starting and it ran for a minuite then died.

below 2500 it will not respond to the throttle and will not tickover

hi mate i know your question was a long time ago but i am interested to find out if you solved the proble as my dt has the exact same problem thanks lee

Have the same Problem on my dt175mx...

Like LC said......the 1st thing that comes to mind is the pilot jet

Definitely sounds like a carb related prob