hi im new to this forum but not to bikes or dt 125 r's i had one a little while ago only a field bike but god was it fast for a old dt my dads got a rm 125 mint from new and it wasnt far behind and we used to race so its not like he wasnt opening it up, it just stayed with it but i stupidly sold it a little while back on ebay for £300! witch i wish i never did
anyway i just brought another dt it had no front sproket and didnt have any feul in it so i got a new sproket and some feul cleaned the carb and spark plug it started 2 kick with the choke on i let it warm up for a minuite or so then went for a little go up the lane before i opened it up but when i did open it up it just reved a litle then bogged i thought oh choke so i turned it off but run for probaly 5 seconds then died and only started when the choke was on so i set off again it probaly gets to about 3/4 of the revs and boggs out any ideas ? i know theres a screw missing on the right hand side of the carb but apparently this only needs blocking from what iv seen on other forums ? and the mixyure screw is siezed should this make a difference ? and also the booster bottle ?? on the inlet manifold is missing but the hole is blocked should this make a difference ? now the engine is noisy and sounds hidious but my mate recently broke one for parts so im going to swap the engine with his one so i have a nice smooth engine hopfully once i have done all of these things it should run better ??
Get a boost bottle, strip and clean the carb replacing ANY missing components, rebuild with fresh gaskets to specified torque settings and you should be good.
When replacing any chains or sprockets you should always replace as a set to allow them to wear to each other. I would advice a new chain and sprocket kit. 50 quid or so on ebay.
Your old bike may well have had the powervalve system set up and working properly and this one may not. Make sure you have the right main jet. 210 is standard up to 1999 then 240 from then on. If you have a sports exhaust, may need a larger jet. From what I've seen 240-250 seems to be the biggest used without major tuning work to the engine. All bikes are different though so be careful and spend some time. It's not an exact science.
