81 kdx175 help please

[Sambino]

I have an 81 that absolutely screams in 1,2 and 3 but when I'm on my way into winding it all the way out in 4,5 and 6 from middle Rpms to WOT rpms the bike will studder and almost fall on it's face I've found I have enough time and speed before it dies to downshift back into 1,2, and 3 and ride it out. The bike will bog then when I wind it out in 1,2,3 but after taking it easy on the bike in 1,2,3 for a few minutes it will eventually act normal in 1,2,3 it's driving me nuts. I did put an 80 I think a-2 carburetor on it because I couldn't find a new brass float for the old one that needed replacement I checked the jetting and it's the same as original one to the bike so I don't think it's that. Could it be the power valve? How would I test that?

 

[glad2ride]

Hi. There are no power vales on that model. The first KDX with a power valve system was the 1986 KDX200.

You may want to check the condition of the reeds. Also, test the compression of the engine, as well as proper output from the electrical components.

If the exhaust is clogged, that could cause an issue as well.

 

[chillywilly]

I has the same problem with finding carb parts as well. I found a float bowl with the two seperate floats on the pins. and it only cost me $10 at a bike bone yard. On a side note, could you tell me what jetting you have in yours, mine is a 82, and I just had the top end resleved. Mine has a sputter in the bottom and mid range, but the top rips.

 

[sr5bidder]

whenever I had this problem it was because the carburator vett lines where clogged up with mud at the ends...so I am going to lay my money on the fuel not getting to the bowl fast enough to keep it full during high demand/high rpm's

* check for clogged carb vents
* check for ample fuel flow from the tank (clogged fuel screen or petcock)
* check fuel tank cap for proper venting

 

[chillywilly]

I was just looking at a online parts fische for our era kdx. If yours is a 81 you should have anywhere from a 152.5 to a 162.5 main and a 40 pilot. The 80 jetting is 132.5 to 142.5 with a 40 pilot. So i wonder if you are lean on the top end if you have the smaller jets. The 80 and 81 also have different slides, needles, and needle jets. Go to www.cmsnl.com and search out your bike. This is the only online parts fische that i have found for the old girls that we ride.

 

[glad2ride]

www.kawasaki.com has the parts diagrams on it.

 

[Sambino]

k I pulled the exhaust off and its clear pulled reed boot and from the outside has some surface rot but the inside looks real good and reeds look great. I took the carb apart once more since I had it off to get to the reeds and noticed the jet needle was a little bent but not terrible. I also noticed when pulling the carb that there was oil build up from
the air filter on the carb air intake ring the guy i bought the bike from has an aftermarket filter and I think it may have too much oil on it. I will be buying a new air filter and trying that. my thinking is that on a long drawn out run it is steadily pulling more and more oil through the air filter fouling the mix.... Make any sense. I will also try and check electrical components. The compression looks and feels good when I pulled the exhaust I looked at the piston and slowly sent it by via kick starter. and it is a pain to kick so I find it hard to believe its compression but I will check that too. Other than that I'm stumped.

 

[mudpack]

k my thinking is that on a long drawn out run it is steadily pulling more and more oil through the air filter fouling the mix.... Make any sense.

Sorry, but no. It would have pulled the excess oil out long ago. Keep looking.

 

[sr5bidder]

have you bothered yourself with the recomendations I gave you yet?
when you clean the carb use compressed air to blow out all of the air and fuel circuits before putting the jets and airsrew and choke back on it.

you can use kerosene to clean the old filter of the oil and re-oil it

 

[Sambino]

totally cleaned the carb all the vents everything checks out. I cleaned the air filter, oiled it back up and went out for a spin. everything was going fine till I came close to full rpm and the bike went to fall on its face and as I was leaning down to reach for the choke to see if that would help the bike took off and started screaming I pulled back the clutch and the rpms soared into scary rotations I hit the kill button and it didn't do anything so I reached down and pulled the plug boot to kill. pulled the plug and it appeared to be normal. So I gave it a kick and it started right up. It continued to act up on me for an hour ride tonight doing the same thing I would get close to full rpm and the bike would just take off I would then ride the brake and it would eventually give me back control but it did this in every gear. It isn't the throttle cable because I just replaced that. The guy I bought the bike from was telling me he was having the same problem with it. The first thing I did when I got the bike from him was replace the throttle cable and man did it need it. Now I'm thinking it was something else as well. Tonight it seemed like the spark was all over the place at one point it stalled on me at the bottom of a hill. I would kick it, it would start it would rev but when I engaged the clutch it stalled. Then all of a sudden after a minute or so it kicked it engaged and it climbed like normal. I'm thinkin its the cdi but don't know how to check this. if the bike is running normal most of the time, do you wait for it to act up to check the current? Thanks everyone for your help and patience... this thing is drivin me nuts but I know I'm close to getting it there and really like the machine a lot

 

[glad2ride]

Timing is off (maybe sheared woodruff key) or an air leak.

Are all the connections clean and dry, free of corrosion, etc?

Good job on keeping with it. I hope you get it figured out.