I have a 1974 dt 250 same as an dt 360 the bike has sat in a barn about 4 yrs it will not start removed and cleaned the gas tank went thur the carb new plug used ignition coil compression about 50 to 75 psi i have spark checked the reeds also loosend the exhaust from the cyl head before any thing was done we got the bike started with carb cleaner it idled real hi 5000 rpm it wont run now the strange thing and this is why i replaced the coil we could get spark thur a bulb type spark tester but when we grond the spark plug to the cyl head to see if thier was spark thier is no spark

I agree - I think I would get a second opinion.

Try a tank of fresh gas with Chevron Techron in it. Do the shock treatment. All Honda's are cold blooded. If the system is just a little gummy this should wash it through with out having to disassemble and clean the carbs. Chevron Techron can be purchased at most auto stores. It is also sold under the name "Yamaha ring free fuel additive" but it will cost double.

Two possibilities.
1. Your float needle is leaking (most likely). Remove the carb, remove the float bowl. You will see the float itself and it has a tang that touches the float needle. Remove the float and inspect the needle and its seat for dirt or wear. You could try gently tapping the float bowl first, as this may dislodge and dirt, but thats a short term solution.
2. The float level is incorrect. You will need to bend the float tang to adjust. However, find out the float height for your bike first.

make sure the coil is earth proerly antry a differnt plug as some times even new 1s are faulty,

check the fuel filter if it is nasty and clogged replace it. probly could use a set of spark plugs as well. worst case the carbs may need to be removed and cleaned recomend a carb soak can for best results as old fuel turns to varnish and clogges up the carb make sure to remove all rubber parts befor soaking or you will have super sized parts. if going this far recomend basic rebuild kit for the carbs they are inexpensive and save alot of headaces.

The brown oil is water mixed into the oil. If I recall correctly the DT bikes were air cooled. The water would be condensation in the gearbox. Just drain the oil and ride more often. If the bike is water cooled the two seals on the water pump shaft are bad. This is not a major repair. The bike probably needs new crank seals. Go ahead and clean the carb as water and trash may have accumulated restricting the fuel flow to the motor. Install an in-line fuel filter.

Use TWO STROKE ENGINE OIL in the pump. If not using an automatic oil pump, then mix the gas and oil 32 to 1. That equals 4 ounces of TWO STROKE ENGINE OIL to one gallon of gas. NEVER use motor oil in the gas. Only two stroke engine oil. Use 10w40 motor oil in the gear box. Don't use any synthetic oils, oil marked "EC", or oil with "special" additives. Stick with the major brands; Pennzoil, Quaker State, Mobil or Shell.

ALWAYS have a fire extinguisher on hand when working on carburetors.
Remove the water trap bowl at the bottom of the petcock, (gas valve). Is there any water or trash in the bowl? Drain a cup of gas from the tank. Is there any water or trash in the cup? Dump it, clean it and re-mount it, ( not all bikes have a water trap bowl ).

Drain the carburetor. There should be a screw on the lower side or bottom of the carb float bowl. Remove the screw then replace it after the fuel drains. Turn the gas back on and wait a minute for the carb to fill with gas. Try to start the engine. If the bike doesn't start and run properly then shut off the gas and remove the carburetor from the engine.

Remove the float bowl and clean the entire carb with a spray carb cleaner from the auto parts store. Wear protective goggles to avoid getting spray in your eyes. Spray into all the little airways and fittings in the carb. Remove the idle screw and the air screw on the outside throat of the carb and spray into the screw holes as well.
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Be sure to put these two screws back in the same hole they came out of. IMPORTANT > do not tighten these two adjusters down. Only screw these in until they LIGHTLY seat. Now turn each adjuster one and one half turns outward. Put the rest of the carb back together, clean the air filter and install the carb. Let the float bowl fill then start the engine.

If the tank is rusting, you need to seal it up. Google “ kreem fuel tank liner “ or go to www.http://www.4secondsflat.com/Fuel_Tank_Sealer.html

Check compression ratio and valves clearance.The carbs leak any fuel from their o-rings.Spray through the air box with a carb cleaner spray while pressing start button but little bit at a time.Don't twist the throttle too much and always use choke until she fires up for good.

I have a supermagna and used fuel stablizer once and it wasnt fit it gummed my carbs up,ive cleaned mine often and it isnt rocket science,remove the tank airbox assembly,loosen up the boot flanges that hook the carbs to the motor(ones on carb)then remove the carbs,then the cables,choke and throttle,do not remove carbs from assembly(leave all 4 together)remove the bottoms and tops of a carb,removefloat and jet,then remove all the brass jets and clean them so you can see through holes,,blow out all the holes in carbs,and reasemble,works for me every time,about two hours to do,good luck

Sounds like you need to clean the carbs out, as they are probably gummed/varnished badly after sitting for 2 years.