DT RE Chris

So I believe the KTM lc2 125 Engine is a clone copy of the DTR 125, but I read that the KTM top end is more powerful due to the power valve and porting, has anyone tried fitting one to a DTR and does it improve performance?

please use the wanted section of the forum ta

So...I was barking up completely the wrong tree, turns out the compression gauge I borrowed was faulty However, I still can't get it running, it seems there's not enough air passing through the carb as it doesn't actuate the vacuum petcock when cranking so no fuel comes out(replaced petcock and no different) If I suck on the vacuum pipe fuel pours out, I even filled the carb with fuel but still nothing, I've tried spraying fuel through the carb when cranking and no good either Reeds and intake pipes and seals have been replaced so its not sucking in air from somewhere else as far as I know. It does almost start but only when holding the starter motor on, you can here it taking a bit of the load off the starter and it turns over a bit quicker but wont quite fire up on its own. Had the carb in bits and again all appears fine, not sure about the auto choke on the carb but even if this has failed it should still run surely? I don't know what to try next as there isn't anything left Any suggestions?

Yes battery power is fine as connected to my car via jump leads so starter motor is turning over better than usual. Not tried removing fuel cap yet but I did turn the tank upside down and it leaked from the cap so I don't think a vacuum is the issue.

I know, I've run FAR worse condition engines with holes and leaks all over the place, its so frustrating as it seems everything is ok, I did wonder about the timing, I know its a CDI unit but I've heard the timing can alter, I have tried two different CDI units on it, however, after I did find the flywheel had worn through the pick up wire and was making contact, could this have damaged BOTH CDI units? unlikely but not ruling anything out now

Original barrel and piston looked fine, didn't need replacing I just did it to rule it out, i'll have another look at fuel but even when I suck on the vacuum and fill the carb it still doesn't fire up

Its a moped

Not recently, but was used on my DT last and read fine, it could be faulty but it doesn't explain why there's not enough air being drawn through the carb, the plug is always dry

Barrel and piston came as a kit brand new and fit very snug and tight, plus the original barrel was giving the same psi reading so doubting there's a fault there

Reeds are fine, and exhaust is clear, it's just not making any sense, I literally tried everything I know and have never come across an engine I can't get running, i'm baffled

Everyone else who's done a compression test on the same model moped is getting at LEAST 90psi some even 120psi. (see link) Carbs not the issue, been checked multiple times, if I suck on the vacuum pipe fuel flows into the carb but when connected the air passing over it isn't enough to open the diaphragm, tried easy start and carb cleaner when cranking but it doesn't even pop,

hi, I have a 50cc 2 stroke moped I can't get started, was working fine then gradually got really hard to start and had no pulling power and lost top end speed, now wont start at all, everything seems to check out fine apart from low compression which is 40psi, thinking the piston rings had worn I just replaced the barrel with a new one which came with new piston & rings, did a compression test and its still 40psi. So, took the barrel back off and checked the seals/gaskets which are perfect, checked the head in case it was warped which looked fine, I even flatted it on some glass after inking it up and cant see anything wrong with it, put it all back together and still 40psi!! Checked the crank cases with a pressure test and no leaks from there, even fitted new crank seals just to make sure. It just doesn't seem to be pulling any air through the carb, if I squirt some fuel manually into the barrel it almost tries to start for a couple of seconds but only with the help from the starter motor turning There's no leaks from around the reeds. It just doesn't make sense, where else can I be loosing compression?

Hmmm, it is tempting as the DTRE seems to be the less powerful DTR model, I've always felt like the CDI is holding it back, I have the Athena 170cc kit on it which definitely improved performance but think there is more I can squeeze out of it

50cc Moped, compression tested at 40psi, So, fitted brand new barrel, piston & rings, compression tested 40 psi again?? Base gasket/ head seals are fine with no leaks Is it possible the air is being forced out the crank seals under compression?

I've just come across a company called "Zeeltronic" that specialises in programmable CDI units for Yamaha's. http://www.zeeltronic.com/page/home.php Has anybody tried one of these as they are quite expensive so just wondering are they worth the money?

So, my DT won't start using the starter motor, you can just hear the motor spinning but not turning engine over. the motor is fine and turns no problem, the big cog behind flywheel(not sure what this is called) also turns freely when starter button is pressed, the rollers on the back of the flywheel appear ok and move freely in and out, but just don't seem to engage, Could the rollers just be worn down?? Can they be purchased separately? if so where?

So, new generator fitted and no difference. Not one for being beaten, persisted and eventually found a dodgy wire AND a dodgy connector pin, I by passed the loom and now the battery charges. The pin on the loom side doesn't look like it can be replaced so was hoping to wire on a new 6pin connector block which plugs into the generator.(see pic above) Anyone know where I could purchase such connector? I didn't really want to have to buy a complete wiring loom just to cut one plug off

Just had a new battery, as I say works fine charged from mains, there's just no charge from the bike. I going to try a new generator tomorrow, probably won't solve it but i'm not going to lie i'm a bit outta my depth with this one so just chucking parts at it and hoping for the best. I'm all for testing the electrics but some of the wire colours don't quite correspond to the wiring diagram so makes life really difficult and confusing for someone with my electrical knowledge.

Everything works when the engine is running and the battery is charged. When the battery gets low the starter motor wont work or the horn but all lights work when running. Fuses are ok. What generator coils do what? are the lights on the same circuit as the cdi/coil, which would explain why they work, and another coil charges the battery? Normally the generator would be easy to test but on this model the generator has six wires coming from it and i'm a little confused on how to test it. As I say, i'm no sparky. Give me a Yamaha to work on any day

I will do a continuity test on that circuit. i'm a little unsure on how to test if the generator coil is giving out enough voltage, obviously I know i'm looking for AC but which numbers on the generator connector block would I place my multimeter prongs to to test it, on 4+5 together? or do I put the earth prong to the battery earth terminal and positive prong to 4+5 individually? Also what kinda reading should I get? Thanks in advance

Pretty sure this ones safe So it looks like the ignition switch is wired on the same circuit as the battery feed, the ignition must work as the engine runs but no feed to the battery, would that suggest the generator coils are ok on this circuit and maybe just a connection break to the battery, or have I miss understood the diagram? By the way I've replaced the rectifier and there was no change.

??? the page worked fine for me, I have Kaspersky and no threats detected, just googled Aprilla sr50 wiring diagram and that's what came up, I tried several times just uploading one from my desktop but it just kept saying the file was too big so I had to find a link. Sorry if its caused any problems, it really wasn't my intention.

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So I was under the impression that 3 wires came from the generator and went into the rectifier and then to the battery, but looking at a wiring diagram(see pic) it appears there's a wire that runs from the generator straight to the battery, surely this would be an AC wire or does the generator produce DC as well? i'm confused

It's actually (dare I say it) an Aprilla sr50, not mine but just said I'd look at it for someone. It starts no problem after charging from the 240v mains and lasts for a few days. I checked the voltage at the battery when running and its no different to when it's not running, so I was thinking either a connection fault or the rectifier?