philhill Posted April 5, 2009 Share Posted April 5, 2009 Hi, I'm a newbie to this site and I have just recently bought a DT 125, 1982 registered. I have got 2 problems with it. The first is the headlights don't work. I have been working on it all yesterday and a bit today studying the wiring diagram to try to get the headlights to work. Question 1. Are they supposed to work off the battery or only when the engine is running as they won't do either! Any help here would be great. Also the engine won't run at higher revs and coughs and splutters, but starts, idles and low/medium revs ok, dropping the needle a notch and breathing unfiltered air helps a little. The main jet is a 140 and I think it should have a 130, carb is marked 4J300. Is the jet swap likely to do it and is there anything else I should consider? Also Alans Performance R&D has been suggested as the place to go to get the jet. Also I had one of these bikes when I was 19, many years ago obviously, and I remember getting a Gianneli exhaust for it that seemed to make it run much better, maybe it was just louder, anyway can you still get these anywhere? I have emailed the company and translated my request into Italian but have heard nothing for a week. Over to you any ideas? Thanks Phil Link to comment Share on other sites More sharing options...
Moderator Airhead Posted April 6, 2009 Moderator Share Posted April 6, 2009 Hi phil welcome to the forum, your bike is a DT125MX, the headlight will only work with the engine running, turn the key to position two and then turn the ligh switch on.. I will check on your carb later but it doesnt sound right to me, I think you jet is too big Link to comment Share on other sites More sharing options...
philhill Posted April 6, 2009 Author Share Posted April 6, 2009 Hi phil welcome to the forum, your bike is a DT125MX, the headlight will only work with the engine running, turn the key to position two and then turn the ligh switch on.. I will check on your carb later but it doesnt sound right to me, I think you jet is too big Link to comment Share on other sites More sharing options...
philhill Posted April 6, 2009 Author Share Posted April 6, 2009 Hi, thanks for your reply, I managed to get the lights working this morning before work. I don't think they were working before as I had to clean up the connections from the dynamo as they where furred up, working nicely now though. I have also noted that the exhaust is leaking from the joint at the cylinder which could be robbing power so will need a new gasket. I have seen two choices ali or copper. which do you recommend? One of the fork legs is weeping oil and they are knocking slightly on the rebound (full extension) so I am wanting to change the oil and seals. I have got some oil seals but do I also need some dust covers/seals and will I need anything else to sort? I also don't know how to remove the steel top cover at the top of the fork legs. The Clymer and the Haynes don't appear to cover this models forks. Chap at Redrose said to insert a screw driver and gradually work round twisting the blade, have tried this but scared of damaging the metal at the top of the fork leg! There are two small holes on the side of the cap, are these for removal using a tool? Also can you suggest where I can get some fork gaiters that fit this model. One more thing, I am planning to convert to 175cc at some point will I be able to use the carb I have got and change jets or will i need another? Oh and one more thing where can I get an original rear mudguard. I think thats it for now. Looking forward to answers from you. Phil Link to comment Share on other sites More sharing options...
Moderator Airhead Posted April 6, 2009 Moderator Share Posted April 6, 2009 Hi, thanks for your reply, I managed to get the lights working this morning before work. I don't think they were working before as I had to clean up the connections from the dynamo as they where furred up, working nicely now though. I have also noted that the exhaust is leaking from the joint at the cylinder which could be robbing power so will need a new gasket. I have seen two choices ali or copper. which do you recommend? One of the fork legs is weeping oil and they are knocking slightly on the rebound (full extension) so I am wanting to change the oil and seals. I have got some oil seals but do I also need some dust covers/seals and will I need anything else to sort? I also don't know how to remove the steel top cover at the top of the fork legs. The Clymer and the Haynes don't appear to cover this models forks. Chap at Redrose said to insert a screw driver and gradually work round twisting the blade, have tried this but scared of damaging the metal at the top of the fork leg! There are two small holes on the side of the cap, are these for removal using a tool? Also can you suggest where I can get some fork gaiters that fit this model. One more thing, I am planning to convert to 175cc at some point will I be able to use the carb I have got and change jets or will i need another? Oh and one more thing where can I get an original rear mudguard. I think thats it for now. Looking forward to answers from you. Phil Exhaust gaskets are the crushable ally type Fork dust seals should also be renewed, to remove the metal caps, I use an electricians type terminal screwdriver with a good sharp edge, tap the cover up at the join line, work your way round evenly, you will soon have a good enough gap to be able to strike it from underneath. It might be an idea to replace the piston rings in the forks too...part mumber 2A6-23157-00 Two off. Dust seal part number is 2A6-23144-00 Two off. One point for concern is the knocking on full rebound, there should be a small spring in each leg to stop this Part number 2A6-23151-00. Gianelli pipes are hard come by now, but you can buy 'Big one' expansion pipes approx £110 new Link to comment Share on other sites More sharing options...
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