wild foamy Posted May 12, 2009 Share Posted May 12, 2009 hi everyone. been having some overheating issues with my DT, its running a cone style air filter, BigOne exhaust, racing reeds and a 60cc bore kit on the original 50cc head, increased the oil pump flow rate and the carb is running a 115# main jet, but over long distances (well, anything much over 15-20 miles or running for more than 30 minutes/1 hour) the power will suddenly fade and eventually the engine cuts, it doesnt seise but the heat can be felt (and smelt) when you are sat on the bike. whats causing it to overheat and how can i fix the problem?, regards Steve-o Link to comment Share on other sites More sharing options...
Moderator drewpy Posted May 12, 2009 Moderator Share Posted May 12, 2009 hi everyone. been having some overheating issues with my DT, its running a cone style air filter, BigOne exhaust, racing reeds and a 60cc bore kit on the original 50cc head, increased the oil pump flow rate and the carb is running a 115# main jet, but over long distances (well, anything much over 15-20 miles or running for more than 30 minutes/1 hour) the power will suddenly fade and eventually the engine cuts, it doesnt seise but the heat can be felt (and smelt) when you are sat on the bike. whats causing it to overheat and how can i fix the problem?, regards Steve-o thought you said your bike was reliable on a previous post Is the timing OK?too advanced and will overheat the engine Link to comment Share on other sites More sharing options...
wild foamy Posted May 12, 2009 Author Share Posted May 12, 2009 nothing wrong with the bike it still runs and aslong as i keep the revs low its fine, how do i check the ignition timing? (no points on this one, CDI) Link to comment Share on other sites More sharing options...
JimR Posted May 12, 2009 Share Posted May 12, 2009 nothing wrong with the bike it still runs and aslong as i keep the revs low its fine, how do i check the ignition timing? (no points on this one, CDI) Check for water in the float bowl .. to check the ignitoin timming get a DTI wind the motor back 1.8mm BTDC and the points should just open ... tbh gapping the points to a set figure at a set point will not work Regards Jim Link to comment Share on other sites More sharing options...
Moderator Cynic Posted May 12, 2009 Moderator Share Posted May 12, 2009 nothing wrong with the bike it still runs and aslong as i keep the revs low its fine, how do i check the ignition timing? (no points on this one, CDI) I remember a post recently that was about DT50 ig timing and the diference between working and not is not a lot so if it was ok before and nothings been touched its safe to assume its ok now. It might need one grade up on the plug. Sounds to me based on what i remember from the big bore i had on a dt in the stone age that your running lean at high rpm, the extra oil wont really be helping if it doesent match the extra fuel used by the engine. You need to go out and ride it to the point where its about to have a strop then kill the motor and do a plug chop to see just whats going on in there. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted May 12, 2009 Moderator Share Posted May 12, 2009 I'm with Jim here, check for water in the float bowl, water is denser than fuel and so will not get sucked throgh the main jet (which just so happens to be the lowest point of the carb) Remember this? April 27th "well, today it happened. for the first time in about 6 months my trusty thrusty little DT let me down . after weeks of sunny weather the heavens decided to open and it has p*ssed it down almost non-stop all day, and whilst i was at school the DT was left outside in the elements for six hours, so i come out and jumped straight on it, started 2nd kick with the choke on and ldled nicely, but as i get to the end of the street it started four-stroking and wouldn't rev above 2-3k, i thought nothing of it at the time because the bike was still cold." Link to comment Share on other sites More sharing options...
wild foamy Posted May 12, 2009 Author Share Posted May 12, 2009 ah, is good point... i cleaned the filter but not the carb. well thats a job for tomorrow. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted May 13, 2009 Moderator Share Posted May 13, 2009 I'm with Jim here, check for water in the float bowl, water is denser than fuel and so will not get sucked throgh the main jet (which just so happens to be the lowest point of the carb) Remember this? April 27th "well, today it happened. for the first time in about 6 months my trusty thrusty little DT let me down . after weeks of sunny weather the heavens decided to open and it has p*ssed it down almost non-stop all day, and whilst i was at school the DT was left outside in the elements for six hours, so i come out and jumped straight on it, started 2nd kick with the choke on and ldled nicely, but as i get to the end of the street it started four-stroking and wouldn't rev above 2-3k, i thought nothing of it at the time because the bike was still cold." Nope i'm going on what my old DT did with the Autesa 60kit and the fuel mixture is wrong, now the weather is warming up the cylinder isn't being cooled as efficiently and its starting to tell. Try searching on the internet for the carb settings on a European DT (spanish would prob be best)as they were 60cc, i used a parts book back in the day but it worked. My old big bored dt went through fuel that fast any crap in the float bowl was immediately evident and if you get water in the jets it stays there and spoils your whole day. Much as a carb clean won't hurt, no i recon its going lean at high rpm. Prob not by a lot maybe lift the needle a notch or two (put the clip in groves lower on the needle) and see. Link to comment Share on other sites More sharing options...
wild foamy Posted May 13, 2009 Author Share Posted May 13, 2009 ive raised the needle a notch when i put the 'kit on because it was bogging down and anything below half throttle. been out on it since 4PM and its been absolutely fine, and i was giving it a good thrash should i maybe try a #120 jet? Link to comment Share on other sites More sharing options...
Moderator Cynic Posted May 14, 2009 Moderator Share Posted May 14, 2009 ive raised the needle a notch when i put the 'kit on because it was bogging down and anything below half throttle. been out on it since 4PM and its been absolutely fine, and i was giving it a good thrash should i maybe try a #120 jet? So it was a bit lean to start with, the 120 may be the way to go but i still think you need a plug chop to be sure. My old 50 was a cantankerous old bastard and needed constant fiddling to get it right when the weather changed. Friday afternoon/evening was often spent tweaking it to perfection. Me and a bloke on a yellow TS with a 70 kit were forever battling, he would find a few mph then i would. Happy days. Link to comment Share on other sites More sharing options...
wild foamy Posted May 14, 2009 Author Share Posted May 14, 2009 Did a plug chop and the plug is chocaltey brown with a bit of carbon buildup on the spark plug, so it looks to be running about right... My mate managed to smash up his Suzuki RMX50 on sunday (chav pulled out infront of him without looking) so now ive got the fastest bike in newbury Link to comment Share on other sites More sharing options...
Moderator Cynic Posted May 14, 2009 Moderator Share Posted May 14, 2009 Did a plug chop and the plug is chocaltey brown with a bit of carbon buildup on the spark plug, so it looks to be running about right... My mate managed to smash up his Suzuki RMX50 on sunday (chav pulled out infront of him without looking) so now ive got the fastest bike in newbury God knows what an RMX is, just make sure you don't go the same way. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted May 14, 2009 Moderator Share Posted May 14, 2009 Did a plug chop and the plug is chocaltey brown with a bit of carbon buildup on the spark plug, so it looks to be running about right... My mate managed to smash up his Suzuki RMX50 on sunday (chav pulled out infront of him without looking) so now ive got the fastest bike in newbury God knows what an RMX is, just make sure you don't go the same way. Link to comment Share on other sites More sharing options...
JimR Posted May 14, 2009 Share Posted May 14, 2009 Did a plug chop and the plug is chocaltey brown with a bit of carbon buildup on the spark plug, so it looks to be running about right... My mate managed to smash up his Suzuki RMX50 on sunday (chav pulled out infront of him without looking) so now ive got the fastest bike in newbury Hi Foamy, I guess you must own the breathed on R1 (the fastest bike in Newbury ?) coz I would doubt a DT50 is the fastest bike there Regards Jim Link to comment Share on other sites More sharing options...
wild foamy Posted May 14, 2009 Author Share Posted May 14, 2009 its the fastest 50 then... 'Zuki RMX is a spanish import Link to comment Share on other sites More sharing options...
JimR Posted May 14, 2009 Share Posted May 14, 2009 its the fastest 50 then... 'Zuki RMX is a spanish import until I send the FS1 down there but as a point which cdi are you using ... have you used a MA50/SA50/MJ50/PW50 setup to replace the original mag or have you used an after market system ? The point is here I have an after market CDI system ready to fit to the FS1 and cannot find enough info on how to set it up , but I guess if you have used an after market CDI you would have crossed this hurdle. Regards Jim Link to comment Share on other sites More sharing options...
wild foamy Posted May 14, 2009 Author Share Posted May 14, 2009 nah im using the stock CDI and mag Link to comment Share on other sites More sharing options...
JimR Posted May 14, 2009 Share Posted May 14, 2009 nah im using the stock CDI and mag hang on when did a DT50 get CDI as std ? I would guess the bikes made in Spain ? i.e DT50MXII along with RD80MXII etc your atvar shows a bike that had C/B ignition so I would guess that the CDI has been fittied from one of the above or from the previous post I can see if you obtained the bike with CDI fitted you would think it to be std. please supply the production code from the CDI unit & from the base plate of the stator in order to work out where the mod was done. Regards Jim Link to comment Share on other sites More sharing options...
pilninggas Posted May 14, 2009 Share Posted May 14, 2009 its the fastest 50 then... 'Zuki RMX is a spanish import the kids i teach made me laugh today in a similar manner, one has just put a flash exhaust on his speedfight and its gone from doing 49mph to 51mph, he was ever so chuffed about it, i was pissing myself laughing! how long til ur seventeen and you can ride the jawa? Link to comment Share on other sites More sharing options...
JimR Posted May 14, 2009 Share Posted May 14, 2009 the kids i teach made me laugh today in a similar manner, one has just put a flash exhaust on his speedfight and its gone from doing 49mph to 51mph, he was ever so chuffed about it, i was pissing myself laughing! how long til ur seventeen and you can ride the jawa? Hi, Back at my collage (Merton Tech) my lecturers would class that as "a fail" and would tell you so ... ( I guess a differece between 2009 & 1976 !) if you are teaching you must supply facts to the studants rather than laughing at them ... there is this point that they could be the m/c mechanics of the future you should tell them where they are going wrong and supply enough tech info in order to back up the statement you made. Regards Jim Link to comment Share on other sites More sharing options...
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