1981 Honda ATC 200 Air/fuel issue

[twheelerk]

Hello I have a 1981 Honda atc 200 I recently rebuilt starts first, second pull no problem, changes through the gears no problem but the only problem I am having is when I give it gas it pops an sounds like it is choking out. I picked up a carb for it seamed too help but still bogs alil when giving it throttle an loses some power…also I have too run this new carb on half choke, any advice would help thanks 

[Mech]

The popping, if it's out the carb then it's running too lean. It sounds like too lean anyway from the description.

Are you sure the cam timing is right ? Are you sure the valve clearance is right ? Those could cause it.

Are you sure the spark plug is good, the right one, and set right ? That could cause it.

Are you sure there is enough fuel getting into the carb ? Have you tried undoing the drain screw on the bottom of the carb and checking fuel keeps running out at a good rate even after the carb has drained ?

Does it idle nicely ? Are you sure there are no air leaks into the inlet manifold ?

Could the exhaust be blocked ?

[Mech]

Do you have a battery in it ? Have you checked the charging is charging, and regulating ?

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[twheelerk]

No it don’t use a battery , today I adjusted the values help alil..what is confusing me is everything like the fuel/air screw or like Adjusting the valves or the cam timing chain tension helps alil but not enough…but today I was riding it I have good power in 3rd an 4th but 1st and 2nd gear wants to hesitate an bog. 

[kp3004x4]

CHK for air leaks from engine side on carb sometimes the carb connection will vibrate loose or the boot itself will crack from heat,or could be simply water in fuel. I've seen all of these problems in the past hope this helps.

[Gwbarm]

My experience is the aftermarket carburetors run too lean I would compare the jet sizes from the old to the new and see if they match, I think Mech and KP covered most of the fixes, the only thing I might add is you could go up on jet size, or drill them out, but if you drill them out, you have to be careful not to get them too large.

[Mech]

How long have you been running it without a battery ? That might be the trouble. 

And Gw's right about after-market carbs.. they always need stripping and checking before use, then some tuning quite often. Unless the old carb is badly worn in the slide I'd reuse that. The way you are describing it I'd suspect that if it is a carby issue, it will be something wrong with the main emulsion tube, that's the brass tube going from the main jet up to the slide needle. The tube has tiny holes in the side that need cleaning, and the drilling it fits into needs to be clean, and the air jet near the air-cleaner end of the carb needs to be clean.

Oh.. the breather hoses need to be clean.. 

[twheelerk]

I don’t no if anyone can here it but that’s the popping, im tryna get out of it. I got a main jet kit coming so hopefully that will fix it. 

[Gwbarm]

Did hear the popping, it seems to go good no hesitation which is what I would expect running too lean, have to jiggle the throttle to get it to go, sound kind of like an exhaust valve pop I would have to hear it idling to determine that for sure. 

[twheelerk]

 So this is it idling I gave it some gas so you could hear how it dies down at the half way mark on the throttle…this is on half choke by the way no choke would almost die giving it gas or just bog n choke 

[kp3004x4]

I would guess your carb main jet is maybe clogged up but let just a little bit in just to run.  Closer inspection could be simple float adjustment needed CHK specs on float. Hope this helps good luck.

[Gwbarm]

Now that I can hear it better it does sound like a fuel issue, there should be an air fuel mixture screw you can try turning it and see if it helps, also the throttle needle you could move it up a notch and see if it helps. This is a new clean carb. 

[twheelerk]

So I got new main jets an still has hesitation in the throttle. I’ve used size #90-#120, everything with the carb is in spec #38 slow jet, #105 main jet, air/fuel screw 2 turns out, float level is at .5 inch. 

[Mech]

Use jumper leads and connect a battery...

[kp3004x4]

Yes,like mech said try a battery,and could be a carb that is just too small for bike ,could try running it on half choke to see if it stops that would be a spot on indicator of running still too lean as mech stated before hope you get it running.

[twheelerk]

My model don’t use a battery, from how my spark plug looked today, I went for too lean to way to rich so now I’m back tracking myself too see why it’s too rich 

[Mech]

It sounds to me like an electrical problem. In the video it sounds like something's switching the ignition on and off really quickly when you rev it up.. That doesn't sound like carby to me.. 

Does it run any better if you turn the headlights on ?

[twheelerk]

That’s the thing..I can’t turn no light switch or anything because the guy I got it off of has it running with only one coil in the stator when it should has two, one for the Ignition which is there an the coil for the lights are not there. Didn’t know it could run like that honestly, I was starting too think the stator is the problem because I checked my plug today an she’s clean so I’m not touching the carb anymore. 

[Gwbarm]

It may be Mech, you mean timing or weak spark, listening to it again I don't hear it at idle, but when you rev it up it sounds like an engine running with the choke on after its warmed up. What I mean is when you first start a cold engine you turn the choke on, after it warms up the engine starts popping like that until you turn off the choke then it runs normal. Maybe running with the choke half on is restricting the air flow it needs causing the popping, are you sure its the right bore carb for that bike.

[Mech]

I reckon if it was revved up with a strobe timing light attached, the spark would stop happening as the rev limit is reached. That's what it sounds like to me listening to the downloaded video..

 

[twheelerk]

 

 

This is a video I made today, like I said everything is in spec, I did take the #105 main jet out an put the original one back in because it ran better. 

[Mech]

If it's a carb problem then it should rev up when you open the throttle and squirt some engine start down there..

[kp3004x4]

I would have to agree with mech