spark, compression, no go! (dt 125)

[MartZ0r]

Hey guys I I picked me up a cheap non runner 1997 dt125r as I finished my last build. This is next years

it had no spark but I sorted that out with another coil I had spare now its got a nice bright spark but still cant get it going, I suspected jetting was blocked because it will try and run for a second then shut off and won't go but if you leave it for a few seconds or kick it over without ignition on, then turn it on it will try and go again

so i stripped the carb down cleaned it out but its still doing the same. Before I rip it apart again can anyone give any suggestions? Leak test is next to check the seals

[MartZ0r]

Does anyone know off hand the compression range for the dt125 motors? 90-100psi pops in my head

Thinking it might have less compression than I thought.

[nightshaddow]

i believe these have a range of between 140 - 180 psi my next dor neighbor has a 2002 re the engine freshly rebuilt and that is at around 175psi
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"WHAT DO YOU MEAN 100 MPH THATS IMPOSSIBLE Its chinese OFFICER."
Current rides CB 125 TDE(the next project) NS125RK ( now on the road ) CB125TDC (soon to be project 17) melody ( the nephews )

[MartZ0r]

bloody hell, i was miles off with that guess then!

thanks mate!

[DeeTee]

[Supermotard37...]

Kills switch?
Kick stand switch?

It's a long shot but try poring some fresh fuel down the spark plug hole put the plug back in and the lead on and give it a kick if you've got at least 100psi of compression the bastard should fire I've had dt's and ktms currently still own one there cracking lil bikes

If you have a spark,compression,and fuel getting to it, it should fire no problem by putting some fuel down the head it will at least turn over for a few seconds also try setting the air fuel mix back to the standard settings,i think the orginal main jett is a 220 or 240 dont hold me to that tho and check the fuses hope this helps

Ps.sorry for being illiterate
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Fuck off..!! "You absolute contraception malfunction"

[MartZ0r]

hey, thanks for the posts. finally got round to checking this. sparking fine still. compression seems pretty solid at 135psi cold.

going to have to run a full leak test to check the condition of the seals. not before checking the reedblock though might not be sealing.

cant really be much else

[bladerunner]

did it run with ok for a few seconds after you put fuel down the plug hole? if yes then its fuel starvation....if not and it tries to fire once or twice when your kicking it over...could be timing ie sheared woodruff key on the flywheel. Always try a new plug when trying the above.
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Current bikes...cbr929, KDX200's, Rd125lc mk2, RGV250's

[trevor saxe-coburg-gotha]

You probably know this but there's a dedicated DT forum out there somewhere, and it seems pretty active iirc. Not sure if it's mostly about/for '70s and '80s DTs though. Might be worth a look. Fwiw I love pretty much all the DTs and hope to own at least one one day.
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"Life is a sexually transmitted disease and the mortality rate is one hundred percent."

Mobylette Type 50 ---> Raleigh Grifter ---> Neval Minsk 125

[Supermotard37...]

Is it possible that when you've fitted a "coil pack" do you actually mean one or was it the stator plate which,I'm sure there the same thing or I could be retarded but let's just say they were the same thing stator/coilpack is it possible that you when you've fitted the coilpack/stator? you have advance or retarded the engines timing causing it to spark but,not at the right point to make the engine run sufficiently ?
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Fuck off..!! "You absolute contraception malfunction"

[MartZ0r]

hey guys, thanks for the replys. the coil pack is a seperate part from the stator plate. timing is fine and woodruff key is intact. the engine is currently out.

Whats this forum your talking about trevor? i know to a DTR125 one but its dead.

passed leak test at 7psi so seals are ok, decided to pull the inlet manifold off to check reeds and noticed some gold stuff plastered inside the cases?

i have seen a faint bit of this on some engines but surely this shouldnt be peeling like this and what actually is it? Very gritty

https://i276.photobucket.com/albums/kk27/MartZ0r06/WP_000629_zps3a414c19.jpg

https://i276.photobucket.com/albums/kk27/MartZ0r06/WP_000628_zps24a1d951.jpg

[unitynotsocri...]

i 'd check the engine compression and check the ignition timing.I would'nt worry about the gold stuff.
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nearly a normal tax paying tosser.......with ferrileness suzi100,cg125,cb125scb100n,cb175,cd100,cj250t,kh250,c15,125 bantam,super 6,rickman gs750,xt500,250rs,dt175,lifan125,dolomite1850,metro,Morris220ld,morrisfg,leyland princess,range rover,corsa,vw camper .now struggling with legs. MORE ORDER = MORE CHAOS

[trevor saxe-coburg-gotha]

[MartZ0r]

thanks guys. never seen that forum but thanks trev, going to take a look

Timing is spot on flywheel end, definitly electrical now though or the carb still needs looking at. going to drop my spare on.

Engine at 135psi and according to some replys on here and a little research on some german sites thats spot on for this engine. (3BN head with lower compression)

I will sort it out

[bladerunner]

If the cage on the big end breaks down it can leave gold/ bronze bits all over the place but never seen one like that if its gritty then get it removed as it won't do the piston/bore or crank any favours when it starts flying about as it will! Also if it's metallic then your plug ain't going to last 2 mins!
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Current bikes...cbr929, KDX200's, Rd125lc mk2, RGV250's

[MartZ0r]

could be onto something then. The crank is in spec according to Haynes and my feelers. crank is nice and tight. Asside from the fact its been run a bit hot if you see the burn marks on the crank pin.

Funny enough there is a lot of bit's so im glad it didnt run. that was my first thought. they were more in the topend though than the bottom. i have cleaned it out now.

i checked the carb again and sure enough it's blocked again.