ryanwilki Posted December 12, 2010 Share Posted December 12, 2010 Hi everyone, Not long back i fitted a big bore kit (60cc) to my 1993 DT50MX. I jetted it all perfect and put new gaskets on. It ran perfectly fine until not long after i had my head skimmed, a whuring type of noise became apparent. It sped up the higher the revs went. It wasnt too loud but seemed to get louder the longer it had been running. About 2 weeks later i lost quite a bit of compression so after a bit of inspection the studs that hold the cylinder and head down were pulling from the crankcase. So i drilled and tapped the holes that they screw into to an M8 thread. I then got some M8 threaded bar and cut it to size. I lock tighted the new studs in place and the problem was solved. I had my compression back. However the whuring noise was still there. Then my clutch cable and coil went, along with my chain and sprockets. I got these parts and 2 weeks later i was up and running. But on the way home from work, the very same day i fitted all the new parts, i was going down a big hill with my clutch pulled in (free wheeling) and the bike started slowing down, then i heard a wierd noise, kind of like a crack. Then it stalled and i lost all my compression. Ever since, it wont start. I have a feeling that when it was stood for the 2 weeks the 2 stroke oil lines cracked or became loose somehow and the barrel wasnt getting any oil, causing it to sieze. Am i right? Anyway, ive spent too much on this engine and i dont think its worth spending much more money on it to get it right so im just wondering what engine will fit my frame and electrics. Anything upto a 125 is considered, i just want it to be a simple out and in job. Thankyou in advance Ryan. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted December 12, 2010 Moderator Share Posted December 12, 2010 Hi everyone, Not long back i fitted a big bore kit (60cc) to my 1993 DT50MX. I jetted it all perfect and put new gaskets on. It ran perfectly fine until not long after i had my head skimmed, a whuring type of noise became apparent. It sped up the higher the revs went. It wasnt too loud but seemed to get louder the longer it had been running. About 2 weeks later i lost quite a bit of compression so after a bit of inspection the studs that hold the cylinder and head down were pulling from the crankcase. So i drilled and tapped the holes that they screw into to an M8 thread. I then got some M8 threaded bar and cut it to size. I lock tighted the new studs in place and the problem was solved. I had my compression back. However the whuring noise was still there. Then my clutch cable and coil went, along with my chain and sprockets. I got these parts and 2 weeks later i was up and running. But on the way home from work, the very same day i fitted all the new parts, i was going down a big hill with my clutch pulled in (free wheeling) and the bike started slowing down, then i heard a wierd noise, kind of like a crack. Then it stalled and i lost all my compression. Ever since, it wont start. I have a feeling that when it was stood for the 2 weeks the 2 stroke oil lines cracked or became loose somehow and the barrel wasnt getting any oil, causing it to sieze. Am i right? Anyway, ive spent too much on this engine and i dont think its worth spending much more money on it to get it right so im just wondering what engine will fit my frame and electrics. Anything upto a 125 is considered, i just want it to be a simple out and in job.Thankyou in advance Ryan. That makes it another DT50mx engine then, afraid you don't have a lot of options. As far as 125 engines in a DT50mx, with those brakes . You had the skills and knowledge to make new stronger studs to secure the head barrel combo, sounds like the head skimming was a step too far for the bottom end especially with the loud crack. Still worth taking it to bits, if for no other reason as to be certain why it failed. There was such an animal as a DT80 that may well fit into the same frame but they were rare 20years ago good luck today. Why not strip and rebuild the lump you have. Link to comment Share on other sites More sharing options...
wild foamy Posted December 12, 2010 Share Posted December 12, 2010 Sadly, as mentioned above you are very limited as to what engines you can put in it, unless you can find a DT80 engine, the 125 would probably be a bit too much, dont forget that you are riding with drum brakes and as i well know they are not the best. strip that engine down, its well worth it, haynes manuals and walkthroughs are available to help you, the parts are dirt cheap and readily availble on eBay/bitzforbikez e.t.c and you will learn a lot about how the engine works. failing that, name your price and i'll have it off your hands Link to comment Share on other sites More sharing options...
ryanwilki Posted December 14, 2010 Author Share Posted December 14, 2010 Ok thanks for the replies. Looks like im going to have to rebuild it then. How much will it cost on average to rebuild it all? But if wild foamy can offer me a good price i'l let you have it mate: it's got 9 month tax & test, new rear tyre, coil, chain and sprockets, air filter, 60cc big bore kit ( all properly set up with new studs, gaskets and jets for the carb, it's had 2 oil changes within 3 months. It's got new mirrors, all new brakes, clutch cable and chain adjusters. I have all the receipts for the work done and have the v5 in my name, only had 2 owners from new and it's a 1993 model. Properly looked after, not ragged around by loads of 16 yr olds. Im in Bolton Cheers Link to comment Share on other sites More sharing options...
wild foamy Posted December 23, 2010 Share Posted December 23, 2010 sounds exactly likemine, but 3 years younger used engines can be found on evilbay for about £50, its hard to tell exactly what you need until you can strip it down and see the real extent of the damage Link to comment Share on other sites More sharing options...
Recommended Posts