please help..my christmas present wont run !!

[brett88]

Hey guys, new to your website and kdx. I have wanted a dirt bike my entire life...so my sister aquired a 1988 kdx from a friend and surprized me in my garage CHRISTmas Eve. I am so freakin' happy....however, the bike "wants" to run strong but will sputter and slightly stall in every gear throughout the RPM range, worsening in the higher gears.
So..I took off the carb. and cleaned the heck out of it and replaced the old gas and the stalling is still there. I have ordered a clymer manual, but in the meantime, does anyone have any suggestions?
plug? top end? :(
Thanks from a newbie
Brett, TN

 

[Fred T]

Check compression. Needs to be above 140 and best if around 190-200.

 

[MX175]

If there was junk in the float bowl of the carb, it could be stuck in the jets now. Before you buy new pilot and main jets, get spray carb cleaner with a red plastic tube and spray that everywhere that you can, through every little hole and passage. You may also need to set the float. Check out a Clymer manual. My libary has one. I know you reoved and cleaned the air filter. Do you have an inline fuel filter? Cleanliness is next to Godliness.

Good Luck,
Mark

 

[canyncarvr]

Is this resolved?

Is the bike at operating temp when this happens? What you describe is very likely what will happen after a choke-cold start for maybe a couple of minutes depending on how far off the jetting is (too rich) and how gently you warm it up.

This may be a good time to say, 'Dress for the crash!' Get protective gear and WEAR it every time you ride. Don't make your sister regret what she talked santa into getting for you!

 

[Nevada Sixx]

check you kill switch to make sure wires arnt grounding with the bars, did you clean and oil your air filter yet? check your silencer to make sure its not clogged also, and clean out the choke of the carb..also, check your water to make sure its green and not milky,, im sure that bike ran good at one time, so it must be something other than the jetting.

 

[Nevada Sixx]

what am i thinking,,check the water? kdx didnt have water jackets back then did they?

 

[MX175]

BRETT how about an update!!!!

Inquirying minds want to know.

Mark

 

[brett88]

bad running christmas present..part 2 (kinda long)

Hey guys,
I am really sorry to those of you who replied and I didnt post a follow up, I have been out of town and up to my ears..wont happen again.
So, heres the deal:

1988 kdx in pretty good shape, but when I get on the throttle in any gear (worse in lower gears) it "wants to run hard" but stalls down low and literally sounds like a box of rocks, but once you get the bike rolling in 4th or 5th gear it smooths out.

This is what I have done sofar to no avail:
1] removed and cleaned air filter
2] emptied all old gas out and replaced
3] new plug
4] checked fuel line from tank
5] changed plug boot and little copper snap insert (old one had an old plug cap jammed sideways,fried,and lodged up into the cap..I thought for sure this was it but .....no.
6] removed carb. and cleaned the he** out of it, spraying in all passages and carefully reassembled and reinstalled.
7] large quantity of four-letter words

I dont really warm the bike up but have ridden it around the subdivision for 15-20 min. and it doesnt improve. (I also have a 98 Cobra with pipes from hell...my neigbors LOVE me..hehheh.)

Could I need carb work? top end rebuild ? a last meal and a cigarette ?

Sorry for the long post but my motorcycle knowledge is limited so if I said something dumb, my bad.
Thanks.

 

[brett88]

changed plug no help

 

[brett88]

whoops, sorry that it took me so long to reply...thanks for your input...I have changed plug, plug boot, copper connector inside boot, changed gas, cleaned filter, and removed and cleaned carb, and checked fuel line.. and it still sounds like a box of rocks down low when you get on it, however, it steadies out in 4th/5th gear @ 40-60 and runs good..I mean you can feel the bike wanting to pull like hell but something is holding it back (it has to be fuel or fire..right ?)

I have not been letting it warm up at all but I have ridden it several times for 20 min or so and it doesnt improve.

Could it need carb work or top end rebuilding..I really think maybe it has to be fuel or fire...it runs kinda like a car with a plug boot off.

My bike knowledge is limited so forgive my ignorance...

thanks, brett

 

[brett88]

One more thing..
Clymer manual on the way..and when I get home I will check kill switch wires and silencer clogging as suggested, but you can hear it down in (or around ) the motor..it really csounds like a box of rocks..then smooths out if you stay on it as the rpms increase.

I will also start and let run for a while 1st, wish me luck.

 

[Glitch]

brett, kdx's have a KIPS exhaust valve which is probably the qulprit to your engine noise at lower rpm. What ratio of fuel/premix are you running? How easy is it to kick, ie. do you feel pressure on kickstarter when the piston reaches top dead center meaning it has compression, or does it feel really really easy to kick, no resistence?

 

[brett88]

hey bro,
- I used 4 0z to 1 gallon when mixing
- When I start the bike, it will usually start within 6 kicks, and if it was ridden within 24 hrs, 1 or 2 kicks, there is not much resistance AT ALL when you start it, and the kickstand doesnt seem to "catch" and give any reststance until halfway down, and sometimes it will not catch at all and woull bust your leg

- KIPS valve ?? Tell me more Obi-Wan

 

[Glitch]

I dont know too much about KIPS, just that practically every new owner of a kdx always wonders and asks why their engine is making a rattling noise until they increase the throttle, the sound is normal though. It would probably be a good idea to go to a shop and have them check the compression. Or you could tear down the bike and lube all the bearing, or replace bad ones, and pull off the cylinder and check it out to see if it needs a rebuild. I knew nothing about bikes when I bought one, and the guy I was buying my cr125 from knew it. I paid $800 and it was worth maybe $300. It needed a new topend, rear tire, rear wheel bearings, seals and spacers, clutch cable, clutch basket... alot. So I tore down the entire bike, down to frame so I could paint it. I learned alot of invaluable experience from this, now I can easily help out my friends with questions about thier bikes. I would suggest you do the same.

 

[limitless]

glitch has a great point, tearing it down will teach you a lot about how it all works. You should always let it warm up before taken off, you don't want to sieze a piston just because you didn't want to wait 5 min. Good luck!!

BTW - don't the kips valves open at mid-high rpms (I.E. it would effect the topend power?

 

[brett88]

So..
Im gathering that the bike has lost compression (due to the lack of resistance, slipping, and play in the kickstart ) So is fixing this something I can do myself, and what would the parts needed be, what would it cost if I took it to Kawasaki (freakin' scary Im sure). The previous owner was a great guy but not exactly Mr. upkeep, so Im sure routine maintenance hasnt been done in at least 3-6 years.
My clymer manual is on the way (snail mail) so I think that will help alot.
I guess I just want to make sure its not something simple before I start ripping the motor apart.
Thanks Guys

 

[canyncarvr]

A kickstart lever that slips or does not engage is unrelated to compression or lack of it.

KIPS systems are notorious for failure, especially in earlier (< H) models. Yours is a C3 model, does indeed have a KIPS, and is air cooled (no water jacket).

If you're mechanically inclined, figure out how to check your KIPS system. Basically, you'll want to remove the pipe and while looking up into the exhaust port, manually activate the KIPS (probably by manually manipulating the activation rod on the RH side of the engine). You should be able to see the subport drums on either side of the main port rotate in sync and return to an 'at rest' state in sync. Also, the mail exhaust valve (a flap in the middle of the port) should raise upon activation, return to a lower position when 'at rest'.

Go to:

http://www.buykawasaki.com

put in your model and year to see an illustrated parts breakdown for your bike. 'Cylinder' shows the KIPS, 'Engine Covers' shows the activation rod and such.

Kinda late, but with the carb off would have been a great time to take the reeds out and check them for condition. They should seat on the cage and not be at all frayed, chipped or cracked.

My KIPS has not ever broken. Generally, people that know (CDave) say that a non-responsive bottom end will be the result of a busted KIPS. Maybe that's because they tend to stick in the 'open' state as opposed to the 'closed' state.

In any case, it needs to be fixed if broke.

Sounds as if you've covered the simpler points.

Now the fun begins, 'eh??

Good luck. Keep us arm-chair-mechanics advised!

 

[MassKDX]

Fist thing you should do is pull out the jets and read the numbers off the jets. This will give us a guide line of your jetting. Jetting varies by temperature and pre-mix. You should go out and buy a pre-mix cup if you don't already own one. That way you can make sure you are running the correct pre-mix. Also how many turns out is your air screw? This is another factor of the bike running correctly. So many things to determine before you actually tear down the motor for a rebuild. Just my suggestions.

 

[brett88]

Okay dudes,
I will print all this off, go home and check them all out and get back to you.
Yall' kick ass. Thanks, Brett

 

[kdxer200]

bret88 turn on the gas