DtMitch

hi guys, my friend has just recently bought an 03 model dt and were both a bit confused with getting it to run properly. the day he got it he rode 25miles home, once home he realised the boost bottle on the side of the airbox wasnt even connected. after reconnecting it i cant get it to idle well, the mixture screw is all the way in and it kind of idles but every now and again the revs build up to around 5k and stay there until you blip the throttle again. the main jet is 240 and i now stock is 210, it has a dep pipe but is it possible for the jet to be too big? i can get it to run and idle fine with the choke on but cant do anything with it off. i recommended that he should buy 210, 220, and 230 main jets but im not sure tbh.

ooohh.well its back together now and sounds exactly the same

ok so top of piston measures 56.40mm and the bore measures 56.98 is this right or does it seem too small?

ok.so ive stripped the top.end down and cant really find anything wrong with the little bearing so it must be the piston and bore. im replacing the bearing anyway and ill let you know how it goes. a create a problem for myselft tho, trying to be clever i thought i could remove the whole top.end as one, and forgot to drain the coolant. so now my crankcase has coolant in it

ok ive just ordered a new bearing and gaskets which will hopefully be here tomorrow, if so ill strip the top end down on saturday and ill post my findings on here. i just really want the rattling gone as im selling in a couple months and it really lets the bike down

hi there guys im wondering if anyone could give me any advice on what to do my bike has an annoying rattling noise which seems to be coming from the top end. it had a +1.0mm rebore just under a year ago by a previous owner and was fitted with a wossner piston, which has always slapped from cold. i have taken the head off and attempted to measure the bore and got 56.97mm as my biggest reading but im guessing it is 57mm, bore looks nice and clean. but i had no feeler gauges to hand at the time. bike starts first kick every time without fail and pulls well through all gears anyway back to the noise. on start up the piston slaps is the prominent noise from the engine, however there is a rattle which seems seperate.to the slapping in the background. the rattle is there at tickover, not so much on acceleration but very distinctive on de-acceleration however is seems seperate from the engine speed. its really annoying and difficult to explain. Any advice would be appreciated, thanks

it most likely is compression related, if you dont have a compression tester take the spark plug out and cover the hole with your finger and kick it over, you shouldnt really be able to keep your finger on the hole but obviously this is far from accurate

i dont know if anyone will read this again but i just want to correct myself to maybe help others in the future. anyway, my chain was quite loose so i went to tighten it today and found the left adjuster to be on 5 and the right on 6

hi again, i changed the gearbox oil and went on a long ride and it seems to have resolved itself. thanks a lot for the advice and if the problem persist then i know who to ask

its just as its running aswell, when its stationary it goes from 1st to 2nd nicely, i really dont know where this screw spring and ball it tho, and i dont know how to upload pics

morning guys, im out working on the bike now and have just removed loads of mud from the front sprocket area, but it didnt seem to make a difference. the engine plug on the left side is very tight and i cant see any screw around the clutch arm so im a bit confused tbh

oh yh another thing it does is that sometimes if can feel delayed between the shif and actual gear change. kind of like its sticking

thanks for the replies, yh it has gearbox oil but i am gonna change it tomorrow anyway. also if that ball is the problem then what is the solution? will i need a new ball or spring?

hi guys i have a problem with my dt changing from 1st to 2nd. it started yesterday after using the bike for some enduro riding, i rode from 10am to 3:30pm with regular cool down breaks. i will say that most of the time i was in first gear with fairly high revs. well now the bike goes into first easily but then struggles into 2nd and is then fine throughout all the gears. is it possible to damage a gearbox from riding in 1st for a long time? any advice will be appreciated

Nevermind ive just had a look online and yes they use studs which i can get for about a tenner for the pair. Its just getting the thread back which is the annoying part, im very hands on with my bike and like doing as much as i can myself. However maybe its smarter to leave this for someone whos done it before, last thing i want is to completly ruin it lol