I recently bought a 72 dt250, ran for the guy I bought it from, took it home and had to clean the carb because it wouldn't start. Got that all cleaned up and it ran fine for like 30 mins. Stopped working thought i fouled out a plug so i replaced that and it starts up again. Well after about another 15 mins of running it stalls out and wont start up again, I tried replacing the plugs again and it wont start. I figured the ignition coil went bad and overheated until it melted the insulation in it. I checked the two small wires on the coil for resistance and Im getting none. Please help whatever you think it might be. I also need to know where i can find a coil for it because they stopped making them, I cant find anything that will work, is it possible to use a coil from another 250 that they still make?

Not that it can't be the main upper ign coil that failed, but I'd 1st look at the points and make sure that they are clean and opening properly.  You'll want to use a flywheel puller (LH outer threads) to access the points and do a good job of cleaning.  If your new to proper point setup tips, just say so and we'll help in that area further
Back the the upper coil - the resistance through the two small wires will be very small - so make sure the ohmmeter is set properly (esp if analog).  In the short time I have right now I'll just say to search for primary & secondary ohmmeter reading and I'll bet my donut & coffee that you need to look under the flywheel.

My coil works on a friends bike, his does not work on mine. I tried bending a spark plug out all the way almost to see if the spark can jump the gap...it does with a yellow spark. Does not look like it is getting fuel because the plug isnt wet at all. Any reasons you would go from running to no fuel at all?

markm065, on 11 March 2012 - 04:39 AM, said:

CHECK THE MUDA&%$#@!EN TIMING AND POINTS!!!

Don't mean to be rude, but I'm STILL frustrated over what happened to me with my stupid KE from 83......... Ran fine for the last guy, got it home, replaced plugs, ran for 10 minutes, dead, replace plugs, ran for 10 minutes, dead. etc. etc. etc......

Open the left magneto cover, adjust that stuff inside there. then make sure all connections are 100%, clean carb, check compression, air intake, and possibly leakdown. If you do that, it WILL work.

What is a leakdown? And im a little confused on timeing....i know you need to put the cyl at TDS and then I dont know what to adjust on the points. Is the Cam adjustable? Sorry I am new to motorcycle engines.

One more thing, I tried to spray starting fluid in the air cleaner (with the cap off) and it still would not run off that, I even put a small amount in the cylinder. Would not even turn over a little. Just got a big backfire after about 3 or 4 kicks.

markm065, on 11 March 2012 - 07:44 PM, said:

I think a leak down is a compression test that tests the entire block? idk I never got that far but they say it's favored over a comp. test in 2 strokes. I'm pretty sure 2Ts (2-strokes) don't have cams but someone please correct me if I'm wrong. As for the exact procedure of setting the points I'd (and you're gonna hear this a lot) refer to the manual and do it off that. Do you have one? I can look around for a free one if you want, no guarantee there will be one though!

markm065, on 11 March 2012 - 08:05 PM, said:

Yeah I got a lot of backfires when trying to force start it. One way to really get it going is to bump start it. This is where you put the bike in N, run down the street next to it, then as you jump on, kick it into 1st (down) and gas it, then as it starts pull in the clutch and keep it from dying by keeping the revs up (remember things like choke, gas on, key, etc. before you start). When you kick it into 1st you'll either hear a "WAAAAaaaaaannnnnnnnnggggg" (not wang, sound it out) then stop, that means something's wrong. If you hear a "BADINGADINGADINGDINGDING" that means it's working.

Also, it isn't recommended you use actual starting fluid (ether) to start a 2-stroke. A 2-stroke is premixed or "oil injected" to where if you're not getting gas you're not getting oil. Which means by spraying a very "dry" flammable fluid in it it will just hurt it more if it starts. Ether is an exclusive product for 4-strokes. What we use is WD-40, works better when it's straight in the cyl, not a sure thing that it will work, but yes I would suggest using it for the first or second bump start.


Ahh yes I almost forgot.... Before I adjusted the points to where it worked 100%, I had actually sprayed WD-40 into the rusty points. Yes, open the cover, see the spinny stator bowl with the coils inside, there'll be some markings talking about TDC, take the WD, and flood that little be-otch with it! Okay not that much, but get a good amount all around in there, but put priority on the points (not the copper coils). This is something easy to do before you get the manual.

Also, what condition are the plugs? Are they all oily? Carbony? You'll want to have a new plug for after you do all this, but not immediately after, after spraying it kick it a few times then replace the plugs and bump start it with the wd-40 in the cyl.

So to recap!
-Buy a new plug
-Spray a decent amount of WD-40 in the stator area with priority on the points
-Close the lid to it
-With the bike turned off, give it a 5 or so mild kicks to get things moving, but don't start it!
-Remove old plug, spray a quick burst of WD into the cyl., replace with new plug
-Walk out to street or a descent, make sure it's fully on (gas in tank, keys on, fuel on, killswitch off, choke on)
-Perform bump start, be ready for it to act weird. In other words, don't freak out if it bursts to life. Because if it comes to life, it's coming to life.

That should be all, but it's 4:00am and I have one heckuva headache so if you think you're missing something or need to do something you probably do.



http://www.dansmc.co...epaircourse.htm
http://www.atvriders.../sparkplug.html


Please ask any questions you have, and I'll do my best to help, 'cause I know this is confusing.

Edited by twistedkeys, 12 March 2012 - 02:12 AM.

Also, be glad plugs are only like $3....My CRs' are $13 EACH

Okay after much frustration...in working today I checked the compression which i should of done in the first place...getting about 30 psi cold...after putting a teaspoon of 10-w30 in there i got 60...which is leading me to believe it might be a piston ring...however...i think i figured out whats worse yet...the &%$#@! who sold me the bike has some very hidden white calk where the headgasket should be and at the base of the engine bowl. &%$#@! screwed me big time, cause I paid for a running bike...does anyone know if i can even get a headgasket and piston rings for this bike? I know this bike wasnt that popular and they stopped making alot of things for it. Should I be looking for a new engine now?

Every 2 stroke that I had to rebuild a top end (piston rings) on stopped running when they get down to about 80psi.  30psi is so low that you may have damage. If they generally stop running when they get below 80psi. Then they don't have a chance to wear to a lower psi. See my train of thought on a holed piston or cylinder wall damage??

You will be able to easily get used and new parts for this bike. Ebay and thumper talk parts store.

Edited by yellowsnow, 12 March 2012 - 05:14 PM.

I cant find piston rings...found the gaskets no problem but the rings i cant find...thumper parts doesnt have the dt2 listed in 72.

Okay I found pistons piston rings and gaskets...now...assuming i need all of these when i tear the engine apart...how will I know if i need the cylinder rebored? or if it needs to be honed?

markm065, on 12 March 2012 - 02:58 PM, said:

Yeah I did forget to mention.....before I did anything I listed above, I replaced the entire top end... It wouldn't hurt to do it, most guys won't buy a 2T without immediately redoing the top end.

The top end? As in piston gaskets and rings right?

ordered a headgasket to start...if the cyl is really bad im going to have it bored and replace the piston and rings with the next size up what do bad pistons cyl's and rings look like?

markm065, on 14 March 2012 - 07:07 AM, said:

http://www.theultral...com/pistons.htm

Thanks, so it will be pretty obvious haha...another thing I know my service manual which arrived yesterday said you can just clean the piston head with a flat narrow chisel. If its just some carbon deposit. How likely is it that a 2 stroke piston is still good if its original which i am assuming it is.

markm065, on 14 March 2012 - 07:16 AM, said:

It will probably be pretty nasty. If you're going to clean it (which you don't HAVE to, it's not a big deal), do it very lightly, take your time, carbon is very very hard to remove, it doesn't have to look brand spankin' new. The only problem I see with doing it is that you don't want any of that crud in your cyl or bottom end, and I mean any of it, keep it contained. That, and because you're increasing the volume of that area, it might have less compression? idk that's over my head... But again, just make sure none of the carbon gets into the cylinder.

Okay thanks you have been a real big help to me through this

markm065, on 14 March 2012 - 07:48 AM, said:

No problem dude, I didn't learn all that for nothing!