Help needed with kdx200 running bad

[briora]

Just got my son a 1984 kdx 200, it's running terrible when first starts it seems o.k. after riding for about 10 minutes it starts to bog real bad I think I could run faster than the bike and will stall. It was running rich when we got it, so we did variuos like clean the air filter, change the gas , plug, and moved the clip up one. started much easier in 3-4 kicks with choke on. But stil runs like shyt soon after. It seems to still run rich by looking at the plug it is a very dark brown & a little wet. Moving the air adjustment seemed to do no good either way all the way in to all the way out. The clip is currently in the second from top position, wondering if I should attemp to go to the top? The guy we got it from said he just put in boysen reeds but didn,t make any adjustments. although I have since we got it. Just trying to figure this one out. I thinks it's when it gets hot it bogs, or a rich problem. I've seen alot of talk on here about Adjusting the main and the pilot. not sure what you guys are talking about, wondering if they atre adjustments I should be making to try and correct my problem. It's all new to me I'm a 4 stroke guy. But with KDX I better learn the 2's.
Thanks

 

[Moose95]

Briora,
The main and pilot are jets in the carb, a lot of people change the size of these jets to compensate for altitude and such. I really can't speak too much about it since I'm a "wrench-in-training", basically learning as I tool on my bike. You mentioned that your bike bogs, I'm assuming that your fouling plugs? What is your pre-mix ratio at? Have you looked on this site for Fredette's comments on your particular bike year group? If you look around here there are members here who own and ride the older KDX bikes, lots of good data out there. Hope that your problem is something simple like a stuck choke and you get it sorted out soon. Good luck!

 

[Superrat73]

Hi there!,
Your problem is probably in the carb...but not definately. When you cleaned the carb, did you remove the 2 jets and blow out all the passages? Also, the bottom of the choke plunger is rubber...what condition is it in? remember, that bike is pretty old and rubber does rot. The reeds that were put on it will not make it run bad unless they are warped. Another thing I have seen is someone put a piston in backwards...on a twostroke, it DOES matter. if you live near sealevel, the stock jetting is right on for a '84. Does it have the stock muffler? It could be carboned up. Last thing to check is the float/valve ass'y. look at the manuel carefully...there is a tiny spring that holds the float valve to the float...is it installed correctly? and, shake the float...does it have fluid in it?
by the way...i have one too!

 

[briora]

it has an answer pipe on it, carb looks good to me it runs good at first. it bogs and dies whenever it gets hot. after riding for about 10 minutes

 

[briora]

i just took out the aftermarket reeds and put the stock ones back in. then i figured that might work so i took it out when i was done and again in like 10 mins it died out. then i pushed it onto the street and jump started it and rode home which is like 2 mins away.

 

[kx125rida295]

U gotta richen up the oil

YO! Nikka u gotta richen up the oil cuz its a older bike and it needs more oil! Just add a little more oil to the gas like 3 ounces or just get a rato rite. Once u richen it up u aint gonna be boggin down ne more. i gotta 2001 kx 125 and my ratio is 32:1 so urs cant be 40:1 on a 84 2 stroke. and if u keep on runnin it wit not enough oil ur gonna blow it up.

 

[woodsy]

Hi:

Diagnostics are tough without actually seeing, hearing, smelling the bike... But I shall try:

Remove your air filter and make sure there is nothing (like to much oil on the filter) keeping her from breathing - now take the pipe off and check it for carbon buildup on its interior walls - check the exaust opening also for the same. Look into the exhaust opening with a flashlight and check the piston for scuffing/ring damage.
It sounds to me like you may very well have a stuck ring/worn top end. Two strokes play all kind of funny little games when they are weak!!

Woodsy

 

[briora]

hey woodsy,
the guy that sold it to me said it wont need a top end and stuff for a couple of seasons. he did a few things to it. new boyeson reeds. aftermarket Answer SApro pipe. let me know if u can b of anymore help.
Thanks, joel

 

[woodsy]

Joel:

If I were in your shoes that comment from the previous owner would really mean only one thing to me - start from scratch!! The way it is in the real world is something like this: NO ONE _ NO WHERE_NO HOW can tell you or I how soon or often any scoot is going to need a topend job!! Items like: air filter maintenance, pipe to jug seal maintenance, riding style, amount of water in the air, type of and amount of oil used in pre-mix, plug heat ranges, ambient tembs, who did the previous top end work (I think you get the point). When ever I have some one tell me something like that (especially 2 years worht of prediction) I get nervous!!
I would suggest that you begin your investigation into the items suggested so you can get your bike fixed and go back to riding!!!! That is really more fun then working on them or even playing on these computers for that matter :)
Let me know how you come out!
CYA in the woods
Woodsy

 

[gooby]

believe none of what u hear,half of what u see.look into everything urself.kx125rida 40:1 is less oil /more gas which tech is a richer mix,rich/lean is about the ammt of fuel not oil in the ratio.32:1 is what a lot of people mix just jet accordingly.ask a kawi shop what u should mix it at if all else fails ? just tryin to help:)
i mixed 32:1 for an 87 kx250 i had

 

[Nevada Sixx]

when you said the plug was 'wet",, do you mean with black oil? or did it look like water?
you may want to repack the silencer and clean out the choke on the carb. a clymer manual is helpful for a bike too.

 

[ACGUY]

I ran thru a problem just like that on an old RM 250, which ended up being a weak ignition. Stator fixed it. No matter what jets, or other combination I had, it still ran bad. Mine was hard to start too. If yours is not hard to start, perhaps another problem like high float level. The float needle in the old bikes gets a ring around the rubber tip, which makes the float travel higher, and extra fuel gets in the motor, and adjustments don't seem to help any. Try lowering your float, and see what happens. It is a low cost effort instead of replacing parts.

 

[briora]

still can't figure it out. so i'll try to list more symptoms hard to start, although with the clip moved up one it will niw start in 5-7 kicks instead of 20. smokes alot when fist started, may be normal don,t know. Hardly smokes at all when warm. Runs good for first 5 minutes then starts to run terrible. Make a loud snap backfire sound when it does start. bogs and can't get out of it's own way when warmed up. I have checked out everyones recommendations on carbs and jetting, but wouldn,t it run bad from the start if it was a fuel problem, plug is a dark brown. checked reeds there ok. mixing 40:1, ......Stumped? poor kid just got the bike and can't ride it. we test drove it and it was fine, but we diddn't ride it long enough for the prolems to kick in. Image a grown man taking avantage of a kid like that by screwing him with this bike. they made a trade and the guy already sold the bike my son traded him so he can't swao back, I appreciate anyone who can help us by taking time to figure it out, 2 strokes are all new to me I ride an xr.

 

[canyncarvr]

Don't change your ratio to 'fix' a jetting problem...which is likely what you have.

I just sped red the posts...but you mentioned at first not being familiar with pilot/main jets ARE, so don't imagine you know what they are.

Take the fuel bowl off. The main jet is obvious..the pilot is in a recessed hole right in FRONT of the main. Check 'em both. Get the numbers off of 'em and post what they are.

Changing to boyesens commonly calls for a slightly leaner jet-set. Your situation got worse with those installed.

Check:

http://justkdx.dirtrider.net

...for basic jetting info.

...but, post what you got to start with.

 

[JasonWho]

---

 

[briora]

thanks jasonwho,
i dont think its the reeds, or fuel mixing anymore... i have done everything to the reeds. i even tried putting the stock ones back in, didn't work. the boyeson reeds are only a few weks old(so he says.) but i wont blelieve all his b/s no more...i am really getting fusterated with this bike. i traded this guy an 86 XR 600 because i wanted to go 2 stroke. then after i traded someone called to buy it like saturday(8/10/02). and now i jsut found an 86 KX250 for sale and i rather have that than a bike full of problems. so i dont know what to do. i am thinking about doing the whole top end job(amybe/ maybe not). let me know what everyone thinks!!! thanks, joel

 

[canyncarvr]

briora:
I don't see any responses from you in reference to how the bike is jetted.

What am I missing? The most likely problem is jetting, but it isn't being looked into?

If one type of leaner change (dropping the needle) makes a noticeable improvement on the bike, how about the others? (pilot and main).

Rejet to CDave's site spec. Clean the air filter. Put in a new plug.

What happens?

Doing the top-end to fix what could be a jetting problem...without knowing what the carb is set to now is, well...silly.

Yeah...you COULD have a compression problem, but you need to start with how the carb is set up.

 

[briora]

Well guys, still no luck. I checked into every suggestion. The jets are stock for the 84 kdx 200 size has not changed. Every piece of the carb has been taken apart and cleaned. air filter is clean, exaust looks good, even tried putting old pipe back on. After all this it still does the same thing. when first startd runs good and has some balls for about 4-5 minutes. Then loses its power. climb a small hill and you'll be lucky to get up. give it gas to try and get it going and the idle never gets up to having any power. Totally stumped.
Took apart the top end, piston looked a little worn (fine wear lines) even brought cylinder and piston to a local cert kawasaki mechanic and he said they are a little worn, but he has seen a lot worse. And it's not bad enough to be causing the type of problem i'm having. Although I question this guy because I have had problems with him in the past. But 2 strokes are new to me and I wanted an opinion. So I bought a compression tester and it read about 75. But I don't know if thats low, and if it is what makes it low. and would low compression make the bike lose all it power after running good for 5 minutes.
Thanks for all your help
Bri

 

[woodsy]

Bri:
75 pds is way low for a cold motor compression check. Make sure that your tester is seated good at the plug hole, kick you bike over several times to build up the pressure on the guage - if it will not pump above 75 pds you have found at least one of your problems!
You may what to read back in the suggestions and discover that this whole top end thing was brought up by yours truley in the first place. The reason why I suggested this cause was because when an engine warms up the cylinder expands and any exsessive piston to cylinder tolerances are worsened by the by this!! I am sure that you dont have a dialbore guage to check this tolerance but a new bore should be no more then 3 thousands difference and wear limit that I like to run on my 2 strokers is 6.. If you take the rings off your piston, clean the jug and piston real good with mineral spirits put the piston back in the jug and check the gap between the two with a feeler guage you can come up with an idea of how much wear there is there. This will not however give you taper or oblong check.
I will say it again (although I realise that I am the only one here going this direction - thats ok though - ol woodsy is used to going against the crowd hahaha), I think you are now on the right track!! Find out where your low compression is at and your bike will perform like it is suppose to (after you get your jetting back to normal)!
Good luck!
Woodsy

 

[briora]

Woody,
Thanks for the quick reply, can always count on you. When I came up with the 75 that was after 1 kick, I wasn't sure how I was supposed to test it. Just went out and did it again but 7-8 kicks this time, it built up more after every kick and started capping out around 140. did I do it right this time?

 

[canyncarvr]

Did you hold the throttle wide open? You should.

140 is fine. You might get there with fewer kicks @ WOT.

Clean air filter, too (you already did that).

You're earlier comments re: ok cold, bad warm.

The warmer it gets, the leaner the jetting needs to be. Still, "climb a small hill and you'll be lucky to get up" is a severe issue. Jetting being off isn't going to be THAT large an issue.

Still, I'd like to see the NUMBERS of the jets you've got. Needle, too.

 

[Y2Z]

your gonna blow your engine! u gotta put at least 20:1 mix ratio in that gas

 

[briora]

jets are stock at 280 & 35, plug is a good tan/ brown and still pretty clean, a little darker in one spot but not much but when I pull it out it's a little wet. The wet looks kinda clear like the mixed gas. I think the bike still smokes a little more than it should, but not sure it's our first 2 stroke. The smoke is whte in case that matters to anyone. anything else you need to know just ask i'll look for it. I am desperate to get this thing running for my son.

 

[jboomer]

You also need to be sure to hold the throttle wide open when you are kicking for the compression test. I don't know what difference this makes, but something I've always been told and always done. 140 isn't a bad compression though. maybe a little low. Everyone else may have a different opinion, but a new set of rings probably wouldn't hurt. They're only a few bucks.

 

[woodsy]

Bri: Know your talking - agree 100% with the previous input on 140 good!! Sounds like topend probs are eliminated! Now I would relook at this previous suggestion:

I ran thru a problem just like that on an old RM 250, which ended up being a weak ignition. Stator fixed it. No matter what jets, or other combination I had, it still ran bad. Mine was hard to start too. If yours is not hard to start, perhaps another problem like high float level. The float needle in the old bikes gets a ring around the rubber tip, which makes the float travel higher, and extra fuel gets in the motor, and adjustments don't seem to help any. Try lowering your float, and see what happens. It is a low cost effort instead of replacing parts.
You could very possibly be seeing a weak high speed coil on your stator!! I am sure that any Kaw dealer could look up the resistance check for that coil. Check it with an ohm meter cold and again when the bike warms up!! It may be as simple as unpluging the CDI box and checking the terminals there (dont take the cover off the flywheel if you dont have to!! Have boughten that repair manual yet? They are worth their weight in 2 stroke oil for stuff like this (wiring/specs ect..). You might want to beg/borrow/steal one asap..
Keep looking - DONT GIVE UP - eliminate the prospects one at a time and you WILL find out what is wrong!
Best of luck
Woodsy