loss of power

miteymike · Post by **miteymike** » 05:50 pm Jul 07 2005

every thing seems to be free and clear no kinks in hoses no blockages anywhere i will check to see what the clip position is and let you know also will try the different plug thanks everyone for all the help

miteymike · Post by **miteymike** » 07:36 pm Jul 11 2005

So i went riding this weekend and everything seemed to be ok. Fuel line completely full, clip in third position, 158 main 48 pilot, air screw 1 1/2 turns out, altitude was around 2000'. Rode all day long then at the end of the day what do you know the bike started cutting out again. If i gave it full throttle the bike would bog down basically it was like the bike was running but wasn't. but if you gave it just a little throttle it was fine for awhile then it would just die but if i turned the choke on i could get it to run again i don't know about all this now i'm lost. it was almost like the bike was possessed or something.

canyncarvr · Post by **canyncarvr** » 08:08 pm Jul 11 2005

Go back to ICs post. Did you do as he suggested? You should.

When it started acting up, the fuel line was still full?

Still sounds like something is restricting fuel flow. Well..gee...with choke on it runs better when hot? That's a purty good clue!

Did I mention re-reading IC's post?

miteymike · Post by **miteymike** » 10:01 pm Jul 11 2005

ya the fuel line is full and none of the fuel ways in the carb are plugged thats why i'm saying that it is possessed or something i'm at a loss of things to do or check other than take it to a shop and i dont want to do that either

Post by **Indawoods** » 11:01 pm Jul 11 2005

If your getting fuel... it's carburation!

But try this... When it does it again.... unscrew the gas cap and see if it runs. A weak ventline will collapse when drawn upon.

I would also think about sending the carb into RB and have it done. And send him a note to check it over well for blockage. Ron cleans them up well. Forget the shop....

IdahoCharley · Post by **IdahoCharley** » 01:20 am Jul 12 2005

If your now convinced that you have fuel - supported by the fact that you ran the bike without problems almost all day. Another item which acts up occasionally and can be a real head ache to figure out because the symptoms vary - is the CDI box. Sometimes the CDI will fail in a way that makes one believe it is a carburation problem: normally they seem to just fail and leave you with a dead bike.

From my experience the ignition coil when it starts to fail will be consistent - usually enough heat and it starts to cut out at high rpm at first and progressively gets worest. Many times when it is cool it will operate just fine. Resistance measurements are reilable way to eliminate this possibility. Takes only a few minutes to check out the coi's resistancel and clean the ground connection. Check hot wire connections.

The ignition wire/spark plug cap. Good tight connection between the wire to cap and the cap to spark plug? Check connection and look for any cracks in the cap. Weird things happen with carbon arcing and loose connection. May want to check the caps resistance. Again only a couple of minutes to check the connections and condition of the plug cap and igition wire and top of plug interfaces.

Stator exciter coil problem? Remove the engine cover then remove the flywheel; spray the stator down with electrical contact cleaner and blow it clean with compressed air. Check resistance readings on the exciter coil. This is more time consuming but if you have a flywheel puller it should not take more than 30 minutes. Look for breaks in the coil wirings and look at all the connections. Any obvious signs of the windings varnish being broken or removed?

I attemped to cover the bases which came into my mind when I read your notes.

I'll go out on a limb here and suggest that you beg, borrow, or steal another CDI unit to try. My SWAG is that ultimately this will your problem - PROVIDED that you really do not have a fuel delivery problem.

P.S. Before subsituting a known good CDI for your CDI check the connections and wiring for the CDI. I know that ours still resides on the top of the airbox cover and I allow the CDI wiring to hold the cover while servicing the air filter. I shove the wiring into a nook on top of the air box before placing the seat back onto the bike but if one forgets one time it appears that the seat could pinch the wires. I'm guessing this would be the common practice for those who have not relocated the CDI.

Good Luck and let us know what you ultimately find out was the problem.

m0rie · Post by **m0rie** » 02:22 am Jul 12 2005

On the 89-94 KDX's the CDI is located on above the radiator on the left side. I believe the 95-05 KDX's have the CDI in the same spot. I think the box IC is talking about is the 12v regulator. Cicone just went thru this with the CDI on his 90 KDX so he should have some good info if he wants to chime in.

-Maurice

Post by **KDXGarage** » 02:34 am Jul 12 2005

m0rie, the '95 and up bikes (perimeter framed) have the CDI and regulator under the seat. Their CDI is where the E model regulator is (on top of the airbox lid). The H model regulator is on a frame rail right behind the airbox lid, and the coil is on the backside of the downtube, or right close to it, about between the tops of the radiators.

Check the connections on the electrical stuff. I have read a few times that the coil can cut out at high RPM.

When I first got started, I didn't know what was what. For what it is worth, the coil is the roundish part connected to the spark plug. The rectangular box is the CDI, and the regulator (keeps the light bulbs from blowing basically) is on top of the airbox.

m0rie · Post by **m0rie** » 09:24 am Jul 12 2005

Jason wrote:m0rie, the '95 and up bikes (perimeter framed) have the CDI and regulator under the seat. Their CDI is where the E model regulator is (on top of the airbox lid). The H model regulator is on a frame rail right behind the airbox lid, and the coil is on the backside of the downtube, or right close to it, about between the tops of the radiators.

I stand corrected Jason - thanks for the correct info

-Maurice

Post by **KDXGarage** » 09:29 am Jul 12 2005

No, no. No correction! I was just mentioning it. I am used to a C and an E, so when I was helping wsjkawasaki work on his '97 KDX220R, I was often saying, "OH. That's different.", "Look how they have that on the newer ones" etc.

It's neat to see how things changed. People mention that the KDX hasn't changed since '95, so I better not mention me wishing I had some of the cool changes on the '88 model.

I think there were more changes from 1987 to 1988 than there were from 1995 to 2005.

canyncarvr · Post by **canyncarvr** » 11:30 am Jul 12 2005

A further ID note: The voltage regulator will have two wires into it, the CDI has..uh...more....five or so.

IC mentioned looking for varnish breeches ('Any obvious signs of the windings varnish being broken or removed?): I don't know about the older models, but the exciter coil is usually pretty well gooped up with epoxy..you don't/can't see the wires as you can on the lighting coil which is made of varnish coated wire. If you have any question which is which (on the 'H' model the lighting coil is on top, the sparky/exciter on the bottom), follow the wires. What goes to your light switch is not the exciter!

Going back to the choke....

A weak spark will have more trouble in a more lean mixture than a more rich one, so spark could be the problem (with one of the symptoms being choke-on=run better).

...but my WAG is for fuel.

My further WAG (not having read the results of ICs suggested tests) is that the suggested tests weren't done.

A sticky float needle will do this. I've seen it myself a couple of times. Try cleaning the float needle seat with a strip of wet-n-dry over a cotton swab..burnish the seat. 400 to start, 600 to finish. If the needle has ANY concentric marks on the black (if it is indeed viton) tip, replace it.

cicone · Post by **cicone** » 03:24 pm Jul 12 2005

Thanks mOrie---I'll chime in. Reasons for crapping out at high rpm? I've first hand experience with the following. Float level off or needle sticking/not seating, main jet wrong size(doesn't apply here as it runs well for a good while before fritzing), clogged silencer packing(again not likely as it would affect things hot or cold). I'm leaning toward the weak spark theory---generally when a CDI goes out it's all or nothing. However, stator coils are a real treat to diagnose---typical symptoms are cutting out or rough running at high rpms and gradual worsening until nada. They also tend to get worse the hotter they get ei. the longer the ride the worse they run. Difficult to test, but disconnect from CDI and check resistance. If under 200 ohms, it's likely bad. Ditto for open circuit. Get a replacement from Rickey Stator ONLY(if he has one for your model year)! The other coil manufactures put out junk---trust me. I chased my tail for 9 months and went through 3 Electrex coils---even destroyed what was likely a good CDI box---only to find that each coil was a POS. If it is the CDI---you can steal a used one on Ebay. The one thing that just doesn't sit right with your problem is the fuel line not being full---just can't understand that. Have you diasassembled the petcock completely and checked the passageways? There's a spring plate on the petcock held in place by two screws. Remove and pull out the lever and check condition of seal and reserve/on passages. Please let us know what you find.

miteymike · Post by **miteymike** » 09:19 pm Jul 13 2005

weel as i said before the fuel part seems to be ok the main line is full and so on i checked the spark and it seems to be very weak compared to my friends rm 125 also i havent had a chance to tear into it real far as for the cdi and all the wiring but when i do i will get back to you all on this and let you know thank you for all the info and again i will get back to you on this as soon as i can

Post by **KDXGarage** » 02:52 am Jul 14 2005

Is the air filter cleaned and oiled properly? What is the condition of the spark arrestor / silencer? Any chance either might be partially clogged?

miteymike · Post by **miteymike** » 09:25 pm Jul 14 2005

ya thats all done also i just decarbonized the pipe and had the spark arrestor cleaned also the air filter is changed religously after every ride what i did notice is that there didnt seem to be any lightning strikes going on with my plug like i thought there should be maybe my cdi box is going out guess i will have to wait and see

IdahoCharley · Post by **IdahoCharley** » 10:33 pm Jul 14 2005

Miteymike - If its a "weak spark" it likely not the CDI box. (Good news for you since that is likely the most expensive component)

The exciter coil on stator, the ignition coil feeding the spark plug, and the spark plug cap and the related connections is where I would focus my attention. Good Luck - Charley

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loss of power