1985 atc200s has spark, won's start

[Sperdue]

First time post, I recovered a 1985 atc200s from an old bike shop in Columbus Ga. It had been sitting for years and do not know what was wrong with it when it was put up. The owner claimed it was probably rusty tank or carb issues. I also purchased what was left of a 1984 atc200s at the same time for parts. Using the parts bike, I got the pulse generator put back together, cleaned rusty tank, changed oil, new carb, new CDI box and now have a small spark with my new spark plug ( can't tell what color spark). After pulling it, the plug is wet with gas but there is no sign of life. I have not done a compression test ( don't have the tool yet). I set the timing and think I got the timing right along with the gap of the pulse generator. Will it no do anything if the timing is just a bit off? I'm new to all of this so I may be missing something simple I hope. Any suggestions before I go buy the compression tester?

Also tried cleaning original carb, cleaned other elect. plugs, and installed fuel filter. With original carb, when pull starting it, gas was shooting into the airbox so i purchased a new cheap carb. (Not sure if the needle was not seating on original.) I even tried a few squirts of starter fluid. HELP!

[ironchop]

You need a compression test. If the compression is too low, no amount of spark or gas will get it to light off.

It's also possible that it's not exactly in time. A single tooth one way or the other can prevent it from starting.

I'm assuming you have a manual to refer to?

After you check that, time to tackle the carburetor. People have been having trouble with Chinese replacement carbs

Sent from my Z958 using Tapatalk

[Sperdue]

Yes I have the service manual. I will try the compression test when I get the tester.
Thanks

[Gabriel]

Be sure to read the paragraph in the book on this.

Do it with a wide open throttle. If you're intent on working over the carb, go ahead and pull it.

Also, if you get a low reading, before you quit; Try it again with a teaspoon of oil poured into the cylinder. If the pressure reading is significantly higher then you know you're valves are probably good. If not, you'll need the whole shebang.
This is nice to know before a top end tear down.

[350for350]

Check your valve clearances. If they aren't in spec, that may be your problem. Check the magnets on the flywheel, if they're rusty this could be your problem.

[Sperdue]

Finally got the compression test. Not too good! It was around 70 before and after the teaspoon of oil. So does this mean a top end rebuild? This would explain why it was sitting for all of these years. Where is the best place to get these parts for the top end?

[Gabriel]

Yes. Total top end. If the pressure did NOT go up with a little oil then you have a bad valve. Send the head to G&H and let them rebuild the whole thing. It's like $150 or so and they clean, inspect and lap in new valves. Hard to do it yourself for that when you consider the labor involved.

If there's no ridge in the cylinder you MIGHT get by with a new set of rings but it seems silly to me to spend the time and not go on and do it right the first time. G&H does a VERY good job and they'll bore it and send the proper parts in return.

[Sperdue]

Good deal. I'll be giving them a call. Thanks

[Tnwildman]

With 70 psi it should run yes that’s is low but will still run. What band of spark plug do you have in it? My 200s only likes NGK plugs.


Sent from my iPhone using Tapatalk

[muthey]

you can also have the spring advancers 180 deg out of whack and you will have spark but at the wrong time, so might want to check that as well on the pulse generator