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?