85 kdx 200 wont go WOT

daverc1180 · Sep 13, 2012

Hello, I have and 85 kdx 200 A1. I have had this bike for awhile but never have gotten to run right. It starts right up and it will revs good untill you try to open it up all the way. once you do try to open it up it acts like it is running against a rev limiter. if you let off and try again its the same thing. if you shift and start over in the next gear, it will do the same thing. if feels like the time when the bike should really take off and scream it falls on its face. Here is what i have done..... i have cleaned the carb several times. unsure of what jet was in it i went to the dealler and they sold me 280 main jet for mikuni. i have the needle all the way down. ( it does not pop or snap the way a lean motor does.) i have checked the head pipe and muffler. i did a compression check if i remember i think it was at 130psi. i checked the reeds and there closed and dont look warped and i did not see any cracks in them. im not sure if i have a fuel problem or an ignition problem. any help would be awesome thank you folks very much

dirt bike dave · Sep 13, 2012

I think your main jet may be too large.

FWIW, the '83 was the A1, and the '85 was the A3. I think one of the only differences between '83 and '85 was the carb.

I had an '84 A2 and the stock main was 260.

I'd play with the jetting some first, but your ignition timing may be too advanced. Retarding the timing will give you some more top end. You will have to pull the flywheel off to change the timing, and that can be a challenge on an old bike.

Make sure your air filter is not over-oiled. A common mod back then was to drill holes in the airbox cover to get more air in.

daverc1180 · Sep 14, 2012

thanks dave, ill try a smaller jet. that was one of my thoughts not knowing what previous owners had done to this bike. and there were no readable numbers on the main jet. i had read somewhere bofore that the main jet should be around 260 but when i went to the kawasaki dealer they sold me a 280 not being sure of what it was suppose to have or what was in it thats what i bought but i woundered if the parts man had made a mistake but i figured he had the specs so i just went with it. i think i will by a 260 and see what happens. right now i do have the stator. i wanted to take a look at the physical condition. i never could find the actual specs for my stator i compared it to some other specs listed on a forum somewhere and mine was about 100 ohmes higher but by not knowing for sure what my specs are suppose to be i left it alone, after all it starts and revs good. thanks for your input i will see what happnes

dirt bike dave · Sep 15, 2012

Stator failure was common on those bikes. Happened to my '84 and my buddies also. On mine, when the stator went bad, the bike would stall after it got hot and not restart right away. Got worse fast, and pretty soon the bike would only run for few minutes then need a long time to restart. Eventually, it would not start. It was very frustrating to diagnose as the stator measurements with an ohmeter were within the manual spec when the bike was cold.

FWIW, I found some parts info online and it showed the '85 did have a 280 main and the '83 and '84 had 260 stock.

daverc1180 · Sep 8, 2013

I apologize for letting this go for so long. My work and family keep me vary busy and honestly i dont think i have touched my bike since the last time i was on here which was a year ago, doesnt even seem like its been that long. Here is an update of what i have done to my bike off and on the past couple weeks. I found some specs on my stator from rickystator, My readings were pretty close maybe 20 ohms difference. Nobody seems to be able to test the cdi so i left it alone. I put fresh gas in the tank I measured it at 32:1. I messed with the timing on the bike. It didnt really really make much difference. I went out yesterday and purchaced a 260 main jet and put it in. Now im starting to get some power! the bike is standing up now when you hammer on it but still bogs as soon as you get the rpms up. the exciting part is when i got into fourth gear and got passed the mid range the engine smoothed up and started screaming. I didnt know the bike would rev that hard. so Im thinking i need to drop the main jet down some more. just not sure how far to take it for now. FWIW VIN is JKSDXNA12FA009636, ENG # DX200AE010751. from what i can tell its an 1985 so it should of had the 280 main. im not sure why if this was just a jetting problem why it was jetted so big

EYY · Sep 8, 2013

Good to hear you've made some progress! You need to go and buy a few new plugs and a few jets and do a plug chop each time you go smaller on the main jet to make sure it's not running lean. There's plenty of info around here regarding that if you don't know how to do a plug chop already. It's amazing how much difference good jetting will make to a bikes power!

once you have the main sorted, you might consider fiddling with the pilot jet too

daverc1180 · Sep 8, 2013

Thanks EYY, I will try to do that this week. I am dtermined to get thing running right just hope i can get it done before we get busy in the farming world which is coming up soon.

daverc1180 · Sep 8, 2013

Now that i have played around a bit on the bike, i have found it runs a whole lot better when its about out of gas, so i must be running way rich yet. I also believe the pilot jet is running rich. My question is why is my back running so rich with the factory jetting? rich enough to the point that it bogs bad in the high rpms. would there be something else causeing my bike to run in a over rich state besides the jetting?

jaguar · Sep 8, 2013

If you are at a high altitude then it will run like it is jetted too rich

EYY · Sep 8, 2013

Has the bike been modified in any way? Pipe, reeds, air box mods? Those are a few things that can have an effect on jetting. As mentioned above, elevation and temperature also need to be taken into consideration. Jetting is just one of those trial end error sort of things. It's a pain to get right, but once it's right you generally won't need to touch it again provided you don't change anything else (I.e exhaust etc.)

daverc1180 · Sep 8, 2013

im in central iowa. I believe im around 1200 feet about sea level. as far as i know my bike is stock except when i first got it home it did not have a silencer so i bought an aftermarket one and put it on. as of right now the lid is off of my air box as i was trying to see if getting some air would lean it up some but truthfully i dont think bike cares if the lid is on or off. Anyway i went from 280 to 260 i suppose ill get a 230 and a 200 I assume they make those sizes. I did notice after riding around today there was oil building up on the outside where the exhaust connects to the engine and starting to build up in silencer. I dont believe it helps that i thaught my 12 year old daughter how to ride the darn thing and she just bearly gets off an idle. Crap i might as well give up now that she knows how to ride ill never get a turn :whoa:

High Lord Gomer · Sep 10, 2013

Another thing to check is the float level. If the float level was sufficiently off and/or the needle wasn't stopping the flow of gas into the bowl, it could be flooding from that but I would expect it to be worse at lower speeds / throttle openings and get better at higher RPMs / throttle openings.

It is unlikely that the pilot jet has an effect on it running badly in the upper RPMs / more open throttle settings. The needle being too high / having the clip in too low of a position could make it run rich too soon, but it sounds like it runs good in the midrange.

Something else to check is if someone put an additional flywheel weight on it. I put too heavy of a flywheel weight on a bike once and it killed the upper RPM power.

daverc1180 · Sep 11, 2013

Thanks gomer for your input. I have the needle position all the way down,(clip in the top position). Im going to buy some smaller main jets and lean the bike out some more. Im just concerned about the fact that the factory jet was 280 and im going to be way less then that. Ive got a 260 in it now and im going to get down around 200 and see how it acts. My concern however is that perhaps there is another issue causing the bike to run so rich. Im going to recheck the float, and take apart the choke and check the seals on the choke plunger. those are the only things i can think of that would cause a rich situation. Unless the bike is taking in oil from the gear casing but i would think there would be a noticable drop in gear case oil level. At any rate i thank all of you that have offered your insight and incouragement.

daverc1180 · Sep 15, 2013

Well I went out and bought some more jets. I made a huge drop today with the jetting. going from a 260 to a 180. the bike still bogs when you rev it half to wot.

The only time my bike has ever reved up is when it was about out of fuel.

Im leaning toward a new Stator. I know the bike starts right up and will idle fine, I have read some posts about weak ignition not burning all of the fuel and mimicking a rich senerio.

I took pictures of my stator and sent them into ricky stator. of course they said I need new ones( not really sure how they know by looking at a picture). they have a pair or coils for 40 bucks so I think im going to try it.

EYY · Sep 16, 2013

Too lean will make it bog too. I'd suggest trying a jet in the middle of those two, before you spend lots of money on ignition components

jaguar · Sep 17, 2013

If the silencer is clogged it will cause that problem. Take it apart and clean it.
Any kind of obstruction in the stinger can cause that problem also. Take the pipe off and remove the silencer. blow into the header. there should be little to no notiicable resistance to flow.

85 kdx 200 wont go WOT

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