'84 Honda 200ES, Poor Running... Ignition?

[tvpierce]

I picked up this bike a couple weeks ago, and joined the forum. I've been tinkering around with it, and am in the middle of diagnosing a poor running issue.
The bike starts and idles, and can be driven around at low speed, but stumbles under load. It always smells like it's running a little rich, and it fouls plugs pretty severely.

Pulled the carb, and it looked remarkably clean: just the slightest bit of sediment in the bowl, zero varnish anywhere, zero build-up in any orifice of the emulsion tubes, jets clean and unobstructed. Set the idle mixture to 2 turns out. No change.

I know the spark is weak, as I can barely see it sometimes, and when I can, it's not strong.

I have a new plug, plug wire, and ignition coil.

The Pulse Generator checks out for resistance: 28.7 ohm (Honda spec is 20-40)
The Pulse Generator gap is set .330 mm (Honda spec is .3-.4mm)

I picked up a new generic/Chinese CDI on ebay per kb0nly's excellent tutorial thread, but it seemed to make the engine run slightly worse... (?) so I switched back to the original.

The source coil checks out for resistance: 257 ohm (Honda spec is 100-400)
With the engine running the voltage output of the source coil is 28v AC, and it remains constant regardless of RPM. Is this correct? Should it be higher? Should it fluctuate with engine RPM?

Any thoughts?

Thanks in advance!

[barnett468]

Hello

Is ALL the gas new or did you add new gas to old gas?

If the gas is old and apple juice color that is most likely your problem.

Do you know the jet sizes?

Do you know if it ran fine with those carb settings?

[tvpierce]

Yes, all the gas is fresh. I've burned 2-3 tanks of fuel through it like it is now -- kind of an unintended governor while my kids are learning to operate it.

The main jet is a 95, the jet needle is a 36J, and the second jet is a 38 -- which I believe are stock for non-high-altitude. Is that correct?

The guy I bought it from never had it running properly. He bought it non-operational with the intention of tinkering with it then selling it. He admitted he didn't know what he was doing, and gave up on it.

Any thoughts about what the voltage output should be for a good Source Coil?

Thanks.

[kb0nly]

Your voltage output sounds good for the ignition coil output. Double check your spark plug gap, and check the wiring on all components of the ignition system just to rule anything out. You said it seemed to run worst with the new CDI, but how was the spark output? Did the spark look a lot stronger? You might have to adjust the pickup on the advancer to get the timing right now. Check the timing as shown in the manual, if the timing is spot on you should see the line on the advancer and the pickup coil matched, now if you want you can advance or retard the pickup coil slightly to see if it makes an improvement. Sometimes i have to advance them just a smidge to get them running smooth, new CDI or not, i think its because of wear and play in the advancer springs that offsets the timing just a bit.

If you got good spark and play with the timing and its still running rich on the plug i would say you have either a carb or valve or even an exhaust problem. Both my 200ES and a 185 i worked on in the last year had rotted mufflers that the baffling inside of them was messed up so the motor couldn't breath very well with the extra back pressure. I replaced my exhaust with a DG setup and the plug reading told the story, went from black and fouled to light tan just from the exhaust swap. A final tweaking of the mixture screw fixed it right up.

Check the valve settings, if your getting lazy opening and closing of the valves from too much slop in the rockers its going to affect it a great deal also. Also check your air filter and if nothing else run without the top on the airbox take it for a spin with a clean plug, just take off the airbox cover and toss your seat back on. This will rule out the air intake being plugged. I had one that a mouse got in and made a home up in the air intake to the airbox, never ran right until we tore it down to clean up everything and i ran a piece of wire up in there and wads of paper and insulation and everything else started falling out.

Like i said, if its got good spark but its still rich, then you got a breathing problem somewhere, a motor is basically a big air pump, you need good flow everywhere.

[tvpierce]

Hi KB.

The plug gap is good and I've checked the ground wires for the coil, and CDI. I didn't notice that the spark was any stronger with the new CDI.

I've done a lot of messing around with the timing: Removed the advance mechanism, cleaned/blew it out, then coated the shaft and weight pivots with a light coating of oil. Now the mechanism is very smooth and free-moving. When the timing is spot on per the manual, it starts pretty well and idles fine, but I advancing the timing a little helps rev a little better (very little though).

The carb is clean and seems fine. The muffer is a little rugged... I'll look at that. If I run it with just the header (for diagnostic purposes only) would that be too free-flowing?

Valves are adjusted to spec, but the intake valve is a bear to get at. Any tips on that?

Air filter is new. I ran it for a few days without and air filter because I didn't have one. It made no difference whether the filter is there or not.

[kb0nly]

Hmm, if your not getting any improvement in spark, then its got to be something else yet. I haven't ever had a bad ignition coil on these but its possible, did you try removing the plug wire from the coil and snipping a bit off for a fresh end? Also do that on the spark plug boot end as well. Sometimes you get a corroded connection on them that adds a high resistance to the wire and the spark ain't for crap.

Sounds like your advancer is good then no worries there from the sound of it. If adjust the carb won't lean it out any then there is still an issue somewhere, i know i fought my carb for a month and gave up and tossed on a new one from eBay, what a difference, i think though that everything was just worn out in mine, i kept it in case i ever want to rebuild it some day.

You could run it without the muffler, header pipe only, but its gonna be damn loud so just a warning, i know cause i did it before when i was going through the exhaust... LOL It will most likely start to run lean, unless your still having a carb issue, but its a good diagnostic just to check your other work.

The intake is a pain no matter what.. The way i usually do them is take off the seat and the gas tank, then you can get a long flat screwdriver down from the top to the adjuster and then get a dog leg 10mm box end wrench and put that on the nut and then insert your screwdriver and your good. I don't usually use a feeler gauge to set them, i do it by feel by grabbing the rocker and wiggling it up and down until it feels right to me, but if you havent done it a lot then a feeler gauge is recommended.

Ok on the air filter, but when you said you ran it without an air filter, was the lid on the airbox or was that off? The airbox gets it's air from a hose that attaches to one of the frame tubes, and sometimes the frame tube gets plugged up with crap from rodents or just general conditions its been used it, i had one full of leaves and dirt. An air hose with a good nozzle on it and a rag works well to form a seal up into that tube and then blow the crap out in the reverse direction.. but try running it without the airbox lid on to rule that out.

I don't know if i can suggest much more then that sounds like you really have gone through it.

[jawalth6]

I know you said its gas is good but you might should drain the carb bowl in a clear jar and see if there's water in it somehow. Just to be sure. You could also spray starting fluid or wd40 in the intake and then try to rev it up. If it worked good then then the carb is your issue.

[tvpierce]

I had a carb kit on order, and it arrived yesterday, so I pulled the carb apart again, and installed the new parts. The carb was still immaculate when I took it apart, so no water or other contaminants are getting in.
Well, the new carb parts made a slight improvement. Throttle was a little more crisp, and the stumble/bogging was a little bit better. But something's not right with this carb: I can close the idle air control all the way down, turn the throttle stop/idle control all the way out, and it still idles very well -- in fact, a little high. When I make those two adjustments, the engine should quit, right?

Regarding air intake: I had tried running it both with the cover on and off the airbox. I'm familiar with the intake path that leads through the frame -- I already have blown that out with compressed air. It was free of obstructions.

So I did the same thing you did KB: I went on ebay and ordered a new carb... $25 delivered! Hopefully that will arrive in the next few days. Perhaps that will solve my drivability issue. But there's still the issue of weak spark. So once I get the carb sorted out, I'll be better equipped to get to the bottom of the ignition system.

As far as checking valve clearance: I did it by breaking the end off my feeler gauge and holding that with a pair of needle nose pliers to get it under the rocker. I was considering soldering that piece of the feeler gauge to a piece of #12 Romex copper wire, then it could be bent to reach. We'll see.

In any event, I'll keep you posted on my progress when the new carb comes in.

Thanks a bunch for your help!

[Flossyb20]

Weak spark could be water or oil in your stator cover...your stator will check out fine, but won't give you good spark when running...

[kb0nly]

Weak spark could be water or oil in your stator cover...your stator will check out fine, but won't give you good spark when running...

The 200ES is a wet stator... Its got oil splashing around the whole time. The timing chain runs on a sprocket right behind the flywheel, the oil is pumped up to the head and returns down the timing chain galley on that side of the motor, so the flywheel and the stator is always wet with oil.

The only other thing i can suggest is try a new pickup coil for the advancer, that could be going bad and causing a weak pulse to the CDI. There isn't too many connections to go through to rule them out and sounds like you have done it all. After replacing the carb and getting the mix looking right reading the plug you might be satisfied, if not back to working on that spark!

You could always get a high output coil and performance CDI, but they really shouldn't be needed just to get the spark up to a good level.

The way you said the carb now is idling too high no matter what you do to adjust it sounds like an air leak between the carb and the cylinder head, did you replace the o-ring on the rubber intake at the head and on the front of the carb? Its included in the carb kit.

[tvpierce]

Hi KB.

I used the old o-ring because it was in good condition (not flat on either side -- previous owner must have replaced it recently), and it fit better (was a little thicker) than the o-ring that came in the Moose Racing carb kit. Good point though about it acting like a downstream air leak. I'll try spraying the seams of the intake with WD-40 and see if that affects the idle.

I received my new stator source coil in the mail yesterday. The brand new one has the same resistance as the one that's currently in there: 257 ohms. Just checked the voltage output of the stator while running: 51 volts. That's double what it was before... not sure why or how. Should the voltage going to the ignition coil primary be the same (51 volts AC), or is it rectified to DC in the CDI box?

Can you do me a favor? Can you measure the AC voltage coming out of your stator source coil with the engine running?

[kb0nly]

I would definitely check the intake, those rubber intakes can crack and cause problems.

So you replaced the stator coil and now you have 51v... Thats really healthy! I can try and measure mine later today when i get some spare time to give you a comparison.

Actually the CDI takes the output of the stator and the pulse from the advancer and steps it up to over 100v to the primary side of the ignition coil, its still AC voltage from the CD to the coil. I haven't measured one of the ignition coils in a while so i don't remember what the output voltage was to the spark plug on the secondary, i should get my high voltage probe out and check that again sometime just to document it.

[tvpierce]

I would definitely check the intake, those rubber intakes can crack and cause problems.

So you replaced the stator coil and now you have 51v... Thats really healthy! I can try and measure mine later today when i get some spare time to give you a comparison.

No, I didn't replace it. I have a replacement, but only tested the resistance of the new (uninstalled) coil vs the resistance of the one that's in there now. They both read about 257 ohms. The

Actually the CDI takes the output of the stator and the pulse from the advancer and steps it up to over 100v to the primary side of the ignition coil, its still AC voltage from the CD to the coil. I haven't measured one of the ignition coils in a while so i don't remember what the output voltage was to the spark plug on the secondary, i should get my high voltage probe out and check that again sometime just to document it.

I was unable to get a reading of the voltage out of the CDI to the primary on the ignition coil. I presume I can't get a reading because it's fluctuating too much and my digital meter can't keep up. (and I don't have a meter that reads peaks) Is there a way to get that reading without having a pricey meter?

[tvpierce]

UPDATE:

The voltage out of the stator source coil is 27 volts, not 51 volts. I got 51 when measuring with my other meter that has a weak battery. While the higher voltage would be nice, at least I know that it's consistent at 27 volts.

I also realized the needle wasn't seated properly in the plunger. I'll correct that this morning and see what that does for the carb.

Checked for air leaks last night: none... it's all sealed up tight.

[kb0nly]

Ok, i didn't get a chance to measure mine yesterday, and its raining today. But i will get to that because now you got me curious. I think i recall reading a spec that it should be 20-30v so i figured your 51v was high but still possible at higher RPM.

As for measuring the output of the CDI, thats tricky because its pulsed to the coil. You can get a peak reading voltmeter but its not cheap. You can also buy a DVA but also not cheap. What i did is built one! A piece of perf board and a project box from Radio Shack along with a few components is all you need. I found a schematic online on another forum where a guy was talking about needing to troubleshoot the ignition system on his dirt bike a few years back, i did save the picture from that forum. Here it is...



If your needle isn't right that could cause all the issues your having also because it will float up and down if its not correctly held down by the spring in the slide.