81' KDX 420 Carb Adjusting After Parts Soak

[DoU420?]

I just bought this bike and it has been sitting in a field for a year. It looks it too but a little tlc might go a long way. Prev owner tried to get started, but paint thinner is hard to burn even with new gas. Took the carb completely apart and soaked in parts cleaner along with the throttle assembly to get the gum out. Pristine now, but I lost all the adjustment settings. I think the idle screw was out 1.5 turns, but the jet needle in the throttle valve has notches in the base for the c-clip. does this allow metered air in the carb as you rev the throttle? Should I start with high airflow and adjust the idle or put the clip at the very end of the needle and start adjusting the idle?

I'd like to go through it and replace the broken or missing pieces but I'd like to get it started first and go from there. The reeds look fine and look like they are sealed up pretty good. Needs a power wash and the headlight has been completely ripped out.

Any help is appreciated

Mike

 

[mudpack]

I just bought this bike and it has been sitting in a field for a year. It looks it too but a little tlc might go a long way. Prev owner tried to get started, but paint thinner is hard to burn even with new gas. Took the carb completely apart and soaked in parts cleaner along with the throttle assembly to get the gum out. Pristine now, but I lost all the adjustment settings. I think the idle screw was out 1.5 turns,
Are talking about the idle screw or the airscrew??
but the jet needle in the throttle valve has notches in the base for the c-clip. does this allow metered air in the carb as you rev the throttle?
This allows metered fuel into the intake tract at 1/4 to 3/4 throttle openings.
Should I start with high airflow and adjust the idle or put the clip at the very end of the needle and start adjusting the idle?
Be safe, and put the clip second from the bottom groove. Then, change it as required...

I'd like to go through it and replace the broken or missing pieces but I'd like to get it started first and go from there. The reeds look fine and look like they are sealed up pretty good. Needs a power wash and the headlight has been completely ripped out.

Any help is appreciated Mike

Save yourself some possible grief and don't powerwash. Use lots of spray-on engine degreaser, a parts brush, elbow grease, then low-pressure warm water to remove grunge.

 

[DoU420?]

Thanks Mud,

There is about 4" of snow on the ground here and 28 degrees so I'll have plenty of time to clean section-by-section, gently.

As for the Idle screw, I see the choke, It pulls up and stays up until pushed down and holy cow :yikes: one of my screws is missing. Just a hair below and to the left of the choke(bottom center of carb) is the missing screw. It has a duplicate port on the direct opposite side that is just a molded dead-end port, which is why I prolly overlooked the (airscrew port?) Should that be screwed all the way in(when I get it) with quarter turns at a time?

Someone told me to listen for distinct changes to the motor as I kick it over when I reach the sweet spot on the idle screw. Which brings me to that, if you keep going further to the left to the corner, you run into the idle screw I think. It is spring loaded with a needle so I assume it is the idle screw(I have that one). No wonder it would kick over, but not stay started. Then I suppose the claim he got it started over at dad's house before he sold it to me was BS?

I get the feeling handing over 200 bux was still a good deal for me... :nod:

Anyways, I'm looking at the justkdx site for setting the floats and I found Babbittsonline for the kdx parts if I can't get them at the local boneyard here. The seat is all torn up, the the foam is still intact... amazingly.

Mike

 

[glad2ride]

That sounds like a good deal to me. Thanks for saving it from a worse fate.

Look on e-Bay for the owner / service manual. It is Kawasaki part number:

99963-0039-01

All of the following assumes that someone has not replaced the stock carburetor with something different.


Here are some carburetor specifications to keep you going:

Main Jet 165R
Air Jet 0.5
Jet Needle 6E2-3
Needle Jet R-4
Cutaway 2.5
Pilot Jet 50
Air Screw 1 1/2
(turns out)
Fuel Level 1-3 mm

The end of the needle that is thicker, with the grooves, is the top of the needle. The pointy end is the bottom of the needle. The highest groove is 1. The lowest groove is 5. The standard position is 3. The needle number 6E2-3 includes a (-3) to indicate the stock clip position.

As one sits on the motorcycle and faces forward, the idle screw is on the left. The air screw is on the right. The choke lever is supposed to flip up and stay, flip down and stay, not flop around. There are no other screw holes shown. There is one vent hose outlet on the left and one on the right.

Other information:

The stock plug is an NGK B8ES. Around here, they are about $1.75 each at major chain auto parts stores. Buy 3 or 4 to always have a new one on hand during any testing. For under $2, it is one part you can 99.9% eliminate as causing any problems. The gap is .6mm (0.024 inches).

Ensure a good ground on the ignition coil to frame mounting area.

One thing to suspect is flywheel and / or stator damage. You don't give off the impression to beat and bang on the flywheel, but just in case :-) , be sure to use the proper tools to remoave the flywheel if need be. It is a 28 year old bike. Don't let a few minutes of impatience lead to a few months of hunting for a rare part. (insert thumbs up emoticon here).

Good luck with it!

 

[DoU420?]

Look on e-Bay for the owner / service manual. It is Kawasaki part number:

99963-0039-01

Thanks, I found one for about 40 bux.

All of the following assumes that someone has not replaced the stock carburetor with something different.


Here are some carburetor specifications to keep you going:

Main Jet 165R
Air Jet 0.5
Jet Needle 6E2-3
Needle Jet R-4
Cutaway 2.5
Pilot Jet 50
Air Screw 1 1/2
(turns out)
Fuel Level 1-3 mm

The end of the needle that is thicker, with the grooves, is the top of the needle. The pointy end is the bottom of the needle. The highest groove is 1. The lowest groove is 5. The standard position is 3. The needle number 6E2-3 includes a (-3) to indicate the stock clip position.

OK, I think these are for a 1980 A1. I have a 1981 B1 so the jet needle is a 6F31 and the plug is a champion N3C.

As one sits on the motorcycle and faces forward, the idle screw is on the left. The air screw is on the right. The choke lever is supposed to flip up and stay, flip down and stay, not flop around. There are no other screw holes shown. There is one vent hose outlet on the left and one on the right.

I have a MIKUNI carb and the diagram for mine (at least from Babbitts) is wrong. All my screws are located on the same side(the right) there look to be two overflow nozzles one on each side and the fuel inlet hose on the left side.

Other information:

The stock plug is an NGK B8ES. Around here, they are about $1.75 each at major chain auto parts stores. Buy 3 or 4 to always have a new one on hand during any testing. For under $2, it is one part you can 99.9% eliminate as causing any problems. The gap is .6mm (0.024 inches).

Ensure a good ground on the ignition coil to frame mounting area.

One thing to suspect is flywheel and / or stator damage. You don't give off the impression to beat and bang on the flywheel, but just in case :-) , be sure to use the proper tools to remoave the flywheel if need be. It is a 28 year old bike. Don't let a few minutes of impatience lead to a few months of hunting for a rare part. (insert thumbs up emoticon here).

Good luck with it!

Thanks for the info! I'll send away for the manual. I typed in my VIN at Kawasaki and it popped up with the B1 listing, don't know how oddball that makes my bike, but I think it will shred the terrain once I fine tune her up.

There's like a motorcycle graveyard here that you can sort through. I havent spent too much time there yet, but I can see that changing. We just got 6" of snow last night, so it will be slow going for the moment...

Merry X-mas

Mike

 

[glad2ride]

Hi. First, don't pay $40 if you don't have to. Check out this one (no, it's not me):

e-Bay item number 400015919796

http://cgi.ebay.com/ebaymotors/1981...tZMotorsQ5fManualsQ5fLiterature#ht_1426wt_756

I copied the information from my own 1981 KDX420-B1 manual, so I am pretty darn sure it is correct. :-)

The time line is:

1979 KDX400-A1
1980 KDX400-A2
1981 KDX420-B1
1982 KDX450-A1

Can you post your engine number? Hopefully, it is a KDX420 engine, not something else with a "correct for whatever the heck engine it is" carburetor.

EDIT: Yes, the picture is wrong, but just check with the seller on that. Hopefully, it is really the KDX420 manual.

 

[DoU420?]

Ok, here's the engine #:

DX420BE001105

 

[glad2ride]

Good. It is a KDX420 engine. The "DX" is what is on a KDX engine. The 420 is the engine model size. The B is the series. I can't remember or don't know about the E. The 001105 means it is the 1105th engine they made.

It sounds like a 1981 KDX420-B1 to me.

Hopefully, the carb on the bike is the stock one. A swapped carb is a too common occurrence on old bikes.

 

[DoU420?]

I'll contact the guy with the manual today to see if he has the B1 and snap it up. I'm at 3000' elevation so there shouldn't be too much to do but get it back to factory specs and go from there.

On a side note, I just snapped off my jet needle putting the screw into the cover that keeps it and the throttle cable secure. Stupid me. I had it out for 3 weeks and there was a rusted square-head screw in it that was a pain in the ass to get out all this time and had it buttoned up but forgot the seal to the lid that screws down that whole assembly to the carb and when I tightened the screw for the second time, snap-o.

Off to the bone yard today. Plus I need to either get a new seat or recover the one I have. The foam is 100% intact, but the vinyl has been shredded and peeled back to the sides. If I ride it regularly, it will be torn up in no time.

Also a complete headlight assembly would be nice, but first things first.

Mike

 

[glad2ride]

See if you can somehow match up an ATV seat cover from "whatever model will work", and have an upholstery shop fit it on your seat. I am thinking the ATV seat cover would be too wide and too long, so the extra could just be trimmed off.

Just keep an eye on e-Bay for parts.

Post a link to some pictures of the bike if you can. Thanks.

 

[DoU420?]

Talked to a bike shop today about the seat. I can get one brand new from babbits for 117 bux, but the upholstery guy might be just as expensive. especially if I want a more durable material, like leather. Bottom line, am I going to keep the bike? I say yes, and even if I sell, it will be a great throw in for the next owner.

I can post some before and after type pics as I go through it and if anyone sees anything out of the ordinary, they can chime in with "Hey, you don't have any tires!" comments. Remember, it's been sitting in a field for a year. That much I believe from the guy.

I'm also gonna get some filter oil to oil up the air filter. It's intact but flaking ever so slightly and want to try and keep as much debris out of the engine as possible, plus it should help with the dust. But after riding a bit I'm sure it will start caking up, but looking at it before you go out to ride for the day should be a good rule of thumb anyways, before you take it off the trailer.

I do need some grip glue for sure. But got a gift certificate to moto-x one shop and will get all the odds and ends there.

I sent away for the manual today, so should have the build specs soon. Thanks for the heads up, it only cost 15 bux.

Will post soon as some of the stores open back up for the new year!

Mike

 

[glad2ride]

Sometimes you can find a seat cover real cheap on e-bay. A friend had his KDX seat cover put on for $20 at an upholstery shop.

A full price cover is around $55-ish.

Good job on getting the manual. It is the best $15 you will spend on it.

 

[DoU420?]

Yeah, i'll call around on the seat.

What type oil do you use for the crankcase? 10-40? It's stamped with the 1liter but that's it. I'm gonna drain it, prolly put new oil in it for 1 month, then drain again. Don't know if I want to crack open the internal engine parts if the seals are ok.

Should be able to take some pics today.

1 more thing about the seat is, I have a buddy that did his Yamaha 250 with the dip in the seat(which I don't have) and he said it was a pain in the ass. Took him 4 hrs of pulling and stapling. So, I'll think about it.

Need to take an SOS pad to some of the spokes to get a bit of rust off.

 

[sr5bidder]

hey 420 I ran accross a seller on ebay last night DCPLASTICS and looks like he has got seat covers for 39 bucks and he also has alot of reproduction plastics for old kawasaki bikes kx kdx looks like a good source

 

[glad2ride]

Try nightmare racing to see if they have plastics. Nightmare is glossy, DC is matte.

10w40 is fine. Don't use energy conserving, as it messes with the clutch.

 

[DoU420?]

My plastics should be ok, they are somewhat oxidized. Here are some picks

[/IMG]
This is the right panel

Left panel still attached to the air cleaner assembly. When I originally got this, there were no screws to hold the panel on. I added new screws and washers as well as a large washer for the wingnut on the airfilter itself. There is 1 of 2 plastic tabs that are broken off that help seat the panel to the air box, but it has a lop all the way around it anyways so it's not that big of a deal.

 

[DoU420?]

Now for the carb. I took a pick of the new allen screw I put in the Throttle Valve. There was a square-head screw in there that was rusted over. What a pain in the ass to get out. Notive the missing jet needle? Sorry so blurry!

Below, you can see the missing air screw. This is the right side of the carb and has the Idle Screw, Choke and Airscrew all located here.

Below, here's the front.

Below: Here's the left side where the fuel hose plugs in. I don't have the other hoses that go to the overflow nipples. I'll prolly get the hoses to feed through the bottom of the frame. I could let them stay bare, but I just don't want to get dirt caked up around any ports to the carb, even if they are outlets. It would just make me feel better.

Here's the back where it plugs into the air box. On the very bottom of the resivior the drain plug was missing the gasket, so I found one in the toolbox, I have a ton, so even if it's not gas friendly, I can replace no prob.

 

[DoU420?]

As for the reeds, I broke the gasket but it's still complete. Don't know if this is a big deal or just replace with new one. They look good and tight to me.

 

[sr5bidder]

you can wet sand those plastics with 600 then 800 then 1000 and they will look good

 

[DoU420?]

Cool, i'll check out the wet sandpaper and keep an eye on ebay for the plastics, I do need the headlight housing, but that is not exactly a high priority at the moment. But I could add a number plate instead.

 

[sr5bidder]

like I said dcplastics has the headlight too

Have you got the bike running yet?

 

[DoU420?]

OK, so the only cycle salvage yard in this city went out of business. So, my options are getting more limited. Went to a big Suzuki shop and took my carb in, plus the broken jet needle. They had a bunch of needles that were close and he gave me a couple to try. I also got a new gasket for the reed cage and some tubing for the carb to handle my overflow ports. I got some filter oil and lubed up my filter and also some grip glue.

Turns out, the center screw that I was missing is NOT the air screw. It's my idle. It's the screw thats tapered so that it raises or lowers the round throttle valve to allow the needle to let fuel in at a measured amount to mix with the air in the chamber before it goes into the intake through the reed valve and spark plug.

And on the stock carb, there seems to be a lever type choke it looks like, but I have a push-pull.

My manual is on its way. I'll look into recovering the seat, guess, i'll need to go get a heavy duty staple gun...

The tank is off as well so I can dump the paint thinner out and get it cleaned out better.

 

[glad2ride]

Try to find a used carburetor on eBay. a used STOCK carb, that is (another bike with the wrong carb, grumble grumble)

 

[DoU420?]

OK, engine brite'd the bike and cleaned it up substantially. I'll pick it apart to get the smaller stuff brushed out. I'll prolly need a new tank strap. The rubber wishbone one that slips on the end of the tank is still intact, but cracked bad enough to spend the couple bucks.

I hope my manual comes today...

I found a cover for 40 buck out the door from VM Racing and I pulled all the staples out of the old one and threw the ragged vinyl in the garbage. I'll need some adhesive to stick the foam to the plastic base, as it's too loose for me and is numbered on the end of the foam with magic marker that tells me it was salvaged or aftermarket.

I'll blow out the tank today and get the ports all clean as well as a vent tube for the cap. Got new bolts to lock down the seat, Home Depot is fast becoming my #1 cycle shop.

 

[glad2ride]

It sounds like it is coming along.

What is the number on the foam? I know Ceet numbered their foam at some point with the Ceet part number.