1985 200x starting issues.

[Atc 200x 1985]

Hello, I am having trouble starting a 1985 Honda ATC 200x. I have rebuilt the top end brand new wiseco 10.25:1 piston and all new gaskets. I know I was not supposed to grind the valves but did not know that until after I have already ground them. Completely stock other than the piston in it. It has spark but weak like not able to be seen in a shaded area outside but I think it is just enough to start. I have replaced the ignition coil and the CDI box and the CDI pickup on the cam still no avail to get a stronger spark... But it still wants to start but it is not able to you can hear it fire like 3 times then die and every other kick it will do that. the carburetor is stock with 108 main jet 40 pilot jet the idle mixture screw is missing the washer and o ring so I don't know if that has anything to do with it the needle is on its 4 setting from the bottom where it should be I think. valves are adjusted to .003 both fire and cam timing are correct I believe. One thing is that before I got a new spark plug the old one that was in it was working but around the electrode area it was grayed and that means that it is running too rich. so does anyone know what is going on with it? I would like to get it going again. If I ever do get it running again I have a dg or either a cobra exhaust for it and I plan to upgrade the carburetor from stock to like a 32 mill or whatever is 2 steps above stock. Also, should I run 93 in the engine now since I upgraded the piston? thanks.

[Atc 200x 1985]

Ok I made a mistake lol I put the piston in wrong... I thought the arrow met intake but I was reading around and it met direction of flow so I fixed that and it runs correctly now. It is getting too much fuel and is hard to start but it runs. any ideas on how to fix that? I have the needle set at the 4th position and the idle mixture screw is 2 1/4 turns out where it is supposed to be, it has a 108 main and 35 pilot. does anyone know the stock jet sizes?

[ps2fixer]

The weak spark might be the cause of hard starting. A spark tester would validate if it's weak or not since it's really hard to tell on a spark plug.

Basically you hook the coil wire up on this, clamp it to the head and set a 6mm gap, if you get spark it's good, if not you have something in the ignition system not right or too weak (bad coil, spark plug cap, weak sator/flywheel, poor connection, corroded wires etc).

Ebay Listing -> https://tinyurl.com/qn4v4hl

That's just looking at the ignition. Jetting the carb makes a huge effect too, don't really know what a good base line for your mods are though.

Here's the stock jet specs (and a ton of more info) on my site.

https://atvmanual.com/honda/atc200x/1985-specs

[shortline10]

Pilot jet is supposed to be a 40 , 35 is way to small .

[Atc 200x 1985]

shortline10 ok thanks I will try a 40 in it. I took the fuel petcock out and it does not have a fuel filter in it so it could be clogging up the jets cause I can shake the machine and it will start again. ps2 fixer I do have a spark tester its one of them with the light in it is that what you are talking about? when I have tested it before it lights up so it may just be normal for it to have weak spark.

[ps2fixer]

A light doesn't really tell you must, it just has some sort of spark. You want a metering device. I pasted a link to an ebay listing to show it, here's the link again. Basically you hook the plug wire to it, other end to engine head, set a 6mm gap and see if it can jump the gap and if it looks healthy or not. If it can't jump the 6mm gap, the ignition system has something in it that's making the spark weak like bad spark plug boot etc.

Ebay Listing -> https://tinyurl.com/qn4v4hl



Also, besides carb specs, my site has the ohm specs for the different ignition parts. Linked it again below. Exciter should be Black/Red to ground, pulse generator should be blue/yellow to green/white. Primary coil in ignition coil is where the black/yellow wire connects to the coil, to the ground/body of the coil. Secondary is ground to spark plug cap end (spec is with or with out cap). With the cap, generally they read about 5k ohms more (5,000 more ohms). If there's an electrical problem, it should show up in those tests. Physically things have to be good too, but the electrical test doesn't know any difference if like the pulse generator has too big of a gap or not.


https://atvmanual.com/honda/atc200x/1985-specs

[Atc 200x 1985]

Ok that link is not working. I do have a meter just like a fluke meter correct? If so when I get home I will test and post a response to what the readings are.

[ps2fixer]

Weird, never had problems linking before on here, maybe the recent changes broke some links. Here's a url shortened version, this one should work. Never had to use these before.


https://tinyurl.com/qn4v4hl

[MrConcdid]

Also, I had a plug that would spark outside the cylinder, but not under compression in the cylinder, I changed the plug to a new NGK on a whim, and whamo! it runs great.

MrC.

[Tri-Z 250]

If there’s one over stock item I have in my back pocket besides race fuel, oil/filters, it’s the love of NGK’s for every machine.
Consider the cable and ends connecting the plug as well, if it’s original.
Now get a ride report with some pics. Here’s to ya

[Atc 200x 1985]

Ps2 fixer ok it is working now I’ll look I to buying it. McConcdid I bought a brand new iridium ngk spark plug cause I’ve read is they take lower voltages to get more consistent spark. Tri-Z 250 I will replace the ends to all the cables and see if that helps. Also for everyone I went back to a 40 jet and it stopped even trying to start so I believe it is was to rich so I’m going to go back to a 35.

[ps2fixer]

The machine wasn't designed for Iridum so I'd run the standard plug personally. It's like the Toyota's that call for the double ground plugs, put an Iridium in them and less power, worse mpg, just overall not as good as the OEM designed plug. Have had two or three different people have the same issue and running the right plug was the thing that fixed it. All the plugs were NGK or Denso btw. I don't know why it effected it, just know it does. The voltage thing I don't really buy, the gap and resistance of the air is what determines the voltage, atleast for my limited understanding of how it works. I'm guessing it's like the "back pressure" thing, a 4 stroke doesn't need back pressure to run right, look at top fuel drag racers. You do need a balanced system, intake, exhaust, and the air/fuel ratio needs to be correct for the whole rpm range.

[Tri-Z 250]

Good info for thought,? Never had a problem but I get the equivalent plugs to stock spec. The plug end of the ignition wire can over time with over service wear contact end. Typically in two strokes, but I chop 1/4” off and reattach the cap if it’s solid shape.

[ps2fixer]

I just worked with a guy recently with a no spark issue. One thing handy is to use a multi meter to test the spark plug wire off the ignition coil and also test the spark plug cap (around 5,000 ohms is normal). If the cap doesn't give connection, then it's wasting energy or won't even spark.

I'm starting to really push the ohm parts out before replacing. Like my T100 pickup, I have a miss in it, comes and goes relating to temp. I have parts machines, so I just started swapping parts, igniter, coils, ecu, etc. I got to the point where the only ignition related part left is injector. Looked up the specs, ohmed it through the ECU connector and all test good except #2 shows 1.2k ohms, yep bad injector. Probably could have saved myself a lot of time if I just ohmed the parts out to diag the problem.

[MrConcdid]

Ps2fixer, I feel the same way, I found a list of values the cdi box needs to run. I omh each pin, if I don't have the correct value there is the problem. I found a good stator and a bad on off switch this way.. never had to take anything apart to find the problem, just better detective skills.
MrC.