wild foamy Posted May 14, 2009 Author Posted May 14, 2009 erm, this bike has deffo got CDI as standard... no points to screw around with, replacement CDI units are available on ebay, ive also got the original DT50MX (UK) publication brocheure which states the Ignition as being CDI. my DT is not an import,
JimR Posted May 15, 2009 Posted May 15, 2009 erm, this bike has deffo got CDI as standard... no points to screw around with, replacement CDI units are available on ebay, ive also got the original DT50MX (UK) publication brocheure which states the Ignition as being CDI. my DT is not an import, Hi Foamy, if thats the case why would this page http://shop.wemoto.com/index.dyn?oid=58343...;cat=ELECTRICAL exist ? The only DT50's I saw with electronic ign were the ones built in Spain & not Japan but I would guess if it Japanise or Spanish its still an import and handled thro Mitsui Machinery Sales at the time. I can see you saying "My Engine has Made In Japan stamped on the cases" which is true also of the Spanish built models as the motor was made in Japan shiped to Spain and assembled to the Spanish factory spec, The same is now true with YZF125 etc which are made at an Italian factory. As I did work on these bikes & you are right every DT50MX was changed from C/B's to CDI after I left the trade ! Regards Jim
wild foamy Posted May 15, 2009 Author Posted May 15, 2009 if it makes a difference i reset my idle mixture screw, was something like 5 or 6 turns out and a bitch to start when cold, so i reset it to 1.5 turns and now it starts first kick but bogs down at low speed (slight tinkering needed methink) bike hasnt overheated for a while now, and im usually thrashing the bollocks off it in every gear when im out with mates...
JimR Posted May 15, 2009 Posted May 15, 2009 if it makes a difference i reset my idle mixture screw, was something like 5 or 6 turns out and a bitch to start when cold, so i reset it to 1.5 turns and now it starts first kick but bogs down at low speed (slight tinkering needed methink) bike hasnt overheated for a while now, and im usually thrashing the bollocks off it in every gear when im out with mates... Hi Foamy, would this be at the point the pilot jet/air screw are replaced with the main jet/needle ? Don't forget the air screw only adjusts mixture strength at idle ... The bogging down may be down to 'advanced needle clip adjustment' married to a main jet & tube that is perhaps slightly the wrong size. With a CDI fitted it would be good to have the i.d code for the CDI unit which from the manuals could show the ignition curve it was designed with. TBH I have a simular problem with the FS1 I am running an after market CDI & the CDI has two inbuilt curves (switchable) and to date I can only get the bike to run right 'low down' on one curve & you guessed top end on the other curve. I would guess my (and your) answer lies with a lot of time spent adjusting the carb to suit the modified engine/exhaust to the ignition curve. Regards Jim
Sami Posted May 15, 2009 Posted May 15, 2009 i have the same problem with mine check your back brake ! also there a hot running engine ... mine gets very hot ..like a little heater .. great for winter also if you feel her die ... gear down and pull throttle , it helps get you to the side lol then give it 2 minutes .. it works for mine .. hope this helps a bit it is a pain in the butt but not much you can do , i've tried alot of things also check your clutch and throttle Raven
wild foamy Posted May 16, 2009 Author Posted May 16, 2009 in winter its not so bad because the exhaust expansion chamber is right next to my right knee at high revs it runs fine with the choke on... just thought that was worth noteing... brakes aren't binding, clutch is regularly adjusted and has only done a few hundred miles since rebuild (plates and springs replaced) if/when it does go the power fades over a space of a few seconds and if you dont back off the throttle it will cut when i get the chance i will take the seat off the DT and have a look at the CDI
Sami Posted May 17, 2009 Posted May 17, 2009 in winter its not so bad because the exhaust expansion chamber is right next to my right knee at high revs it runs fine with the choke on... just thought that was worth noteing... brakes aren't binding, clutch is regularly adjusted and has only done a few hundred miles since rebuild (plates and springs replaced) if/when it does go the power fades over a space of a few seconds and if you dont back off the throttle it will cut when i get the chance i will take the seat off the DT and have a look at the CDI in my experince with my dt is is just there little thing mine was rebuilt and within 2 hours she cut out like that winter i find she doesnt cut out as much unless its raining >< the high revs are a bugger to get right , mine just ticks over with out the choke on since my dad altered the clutch and stuff . CDI .. optional? i'd take it out if it is. x
JUST ME! Posted May 17, 2009 Posted May 17, 2009 G,day Foamy! Go up a size with the main jet and see if this improves things. Still sounds a bit lean to me. Remember way back when we suggested slightly rich was a far better way to start! If it is actually running so much better with the choke on, you may have to go up a couple of jet sizes. When you do get it right it may also be worth running a plug one unit cooler. I would'nt continue to fang it until it is right or you will risk ruining another big bore kit.HAVE A BLAST. Paul.
wild foamy Posted May 17, 2009 Author Posted May 17, 2009 thanks everyone, it doesnt run noticeably bette rwith the choke on but ti continues to run, if i ease up on the throttle and start curising at low-mid revs it will bog down. will try a slightly large main jet and see how it goes
Moderator Cynic Posted May 17, 2009 Moderator Posted May 17, 2009 thanks everyone, it doesnt run noticeably bette rwith the choke on but ti continues to run, if i ease up on the throttle and start curising at low-mid revs it will bog down. will try a slightly large main jet and see how it goes You may find it slower by a little when the mixture is right. Your engine will use a little of the fuel in the cyl to keep the upper cylinder temperature down. This will prevent you holing pistons/smearing the rings down the barrel. If you run the engine at a leaner mixture you may go quicker but without the cooling effect of the fuel the engine won't last. If the bike wants choke to run at higher speeds ITS TOO LEAN. Seriously Foamy get this right or you will be killing another bore. Every time the power seems to drop of is a heat sieze, fact. The engine may be ok once it cools but every time it happens you are stressing the engine in ways its not designed to tolerate. You are weakening the rings, little end etc. Whats the next post, Oh my rings have broke, why. You have a responsibility to the engine, you cant run a ferrari on the cheap and the work you have put into the engine means you will be a real tit if you let it down for a couple of quidsworth of brass. You need to look at the overall settings and the way the bike is responding, remember: Pilot jet idle/jet needle First 10-15%, Needle jet 20-50%, Needle/ main 50-80% with the main the last 20% It may be the case you need a considerable increace in main size but drop the needle down by most of its travel.
Moderator Cynic Posted May 17, 2009 Moderator Posted May 17, 2009 Here is an example of what i was on about in the last post: DT175 (2X2/2K4) DT175 (4J4) Manufacturer/ Mikuni Type/ VM24SS IDno/ 2h500, 3U500 Main Jet/ 130, 160 Main air jet/ 0.5 Jet needle/ 4J13, 4J6 Clip position (groves fr top) 3rd Needle jet/ 0-4, 0-8 Throttle slide cutaway/ 2.0, 1.5 Pilot jet/ 25, 20 Pilot air screw (turns out) 1.5 Float valve seat/ 2.5 Starter jet/ 20 Float height/ 21mm+/-1.5mm (0.83+/-0.04 in) Idle speed/ (rpm) 1300-1400 1500+/- 50 Where the gaps are on the 4J4 the earlier model carries over. I know there are differences between the 2 bikes but nothing like your bigbored,race piped,k+n'd rocket ( ) Most importantly as far as the example goes they are the same CC, yet there is a 30 point difference in the main jet with a different needle. Food for thought?
JimR Posted May 17, 2009 Posted May 17, 2009 thanks everyone, it doesnt run noticeably bette rwith the choke on but ti continues to run, if i ease up on the throttle and start curising at low-mid revs it will bog down. will try a slightly large main jet and see how it goes Don't forget to remove the water from the float bowl !!!
wild foamy Posted May 17, 2009 Author Posted May 17, 2009 given the carb a strip down and blown out the jets with compressed air. the engine doesnt NEED choke to run at full throttle, merely it WILL CONTINUE TO RUN. the needle is in the lowest notch already.
JimR Posted May 17, 2009 Posted May 17, 2009 given the carb a strip down and blown out the jets with compressed air. the engine doesnt NEED choke to run at full throttle, merely it WILL CONTINUE TO RUN. the needle is in the lowest notch already. Hi Foamy what does that mean ? so I guess the bike runs like poo over ½ throttle but hey you know better than me ! Regards Jim
Moderator Cynic Posted May 17, 2009 Moderator Posted May 17, 2009 given the carb a strip down and blown out the jets with compressed air. the engine doesnt NEED choke to run at full throttle, merely it WILL CONTINUE TO RUN. the needle is in the lowest notch already. Thats why its running a bit off, if you go up on the main jet you can lower the needle position and keep your midrange as well as prevent the high rpm issues.
wild foamy Posted May 17, 2009 Author Posted May 17, 2009 bike runs absolutely fine, after mid-range it gets onto the powerband. with the 115 jet i currently have the needle in its lowest position, so by going up another jet size i would not be able to lower the needle
Moderator Airhead Posted May 17, 2009 Moderator Posted May 17, 2009 Do you run with WOT all the time?
Moderator Cynic Posted May 18, 2009 Moderator Posted May 18, 2009 given the carb a strip down and blown out the jets with compressed air. the engine doesnt NEED choke to run at full throttle, merely it WILL CONTINUE TO RUN. the needle is in the lowest notch already. bike runs absolutely fine, after mid-range it gets onto the powerband. with the 115 jet i currently have the needle in its lowest position, so by going up another jet size i would not be able to lower the needle Sorry WF but this is confusing, the 'proper' way of discribing the needle position is counting the groves from the top for the clip position. Are you saying you have the clip in the top groove or the bottom grove? How can you say she's running fine when at the start of the thread the bike was heat siezing if you run more than 20-30 miles?
wild foamy Posted May 18, 2009 Author Posted May 18, 2009 needle is in the top groove, i was running the bike at WOT most of the time but lately ive been using the gears a bit more and not thrashing it to the same extent, sionce then it has been absolutely fine, no power loss or cutting out
Moderator Airhead Posted May 18, 2009 Moderator Posted May 18, 2009 needle is in the top groove, i was running the bike at WOT most of the time but lately ive been using the gears a bit more and not thrashing it to the same extent, sionce then it has been absolutely fine, no power loss or cutting outI dont think that the needle being in the top groove is wise, this will be making it lean at less than WOT. You may be actually delivering LESS fuel at part throttle than when it was a standard bike. If anything I would have expected you to be using either the standard clip position or one of the clip positions below, thereby richening the mixture. (Which is why you fitted a bigger main jet)
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