KDXRIDER.NET

SO many posts about being overly rich, with 38 /138 and aftermarket pipes, no airbox lids, spooge everywhere. Soooo many posts where people try 100 things to get their mixture right, the jet block, all that crap...

I'm beginning to think we're just experiencing a ton of 20 year old carbs wearing out at the same time.

It's time for someone to buy a new carb, and put the "but you can fix an old kdx carb" myth to bed.

i'm searching ebay/amazon/craigslist for either an air striker or NEW stock carb. i'm completely done with making excuses for the bikes jetting, the poor power, the absolutely **** fuel economy.

let's find some new carbs for these other wise great machines !

Jetsrus has the new pwk's from $180 to $200

Yeah, parts do wear out and the carb is one that can be affecting by the smallest of wear. RB has new modded carbs for sale. PWK for $335 and Air Stryker for $355. For the record, my 220 with RB carb is getting around 110-120 miles to a tank.

What modern carb will fit right on the KDX?


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Cturbo wrote:What modern carb will fit right on the KDX?

A new PWK or Air Stryker.

carbs "wearing out"? what?
does all that gasoline going thru the jets wear down the inner surface so that they need new jets? (no)

I have seen slides so worn (my original '90 carb) that it would bind and hang up. Jets actually do get harmed by modern fuels in the US that contain alcohol. Letting them sit for extended time with this fuel in the carb clogs and corrodes the jets sometimes so bad they need to be replaced.

Jaguar wrote:carbs "wearing out"? what?
does all that gasoline going thru the jets wear down the inner surface so that they need new jets? (no)

yes, this is planet earth, gravity and friction happen here Two materials coming in contact will cause wear, deflection, friction, stress, etc...no matter how small or seemingly impossible to measure, its still happening... unless you got some space age, no friction materials in that sucker!

lol honestly they probably do after all that time. The ethanol corrosion from today's fuels probably don't help much either.

If you checked everything as described, changed the jet block gasket and still can't figure it out, trying a new one may not be a bad idea. If I messed with something small for months and still couldn't get it right, I'd happily dump $300 from the stash fund to get rid of that headache and bring on the braap

Jaguar wrote:carbs "wearing out"? what?
does all that gasoline going thru the jets wear down the inner surface so that they need new jets? (no)

things that are metal on metal contact will wear each other out:

needle point and body
slide
float pivot (mine is very worn)
float needle
flout needle seat
cap and gasket
jets, yes, they wear

the jet block gasket looked like a really good thing to replace, but here we are again, still rich and barely 20mpg.

my truck gets 26mpg, at 75mph.

looking for a new carb

SS109 wrote:Yeah, parts do wear out and the carb is one that can be affecting by the smallest of wear. RB has new modded carbs for sale. PWK for $335 and Air Stryker for $355. For the record, my 220 with RB carb is getting around 110-120 miles to a tank.

this fuel economy sounds incredible. three times what mine gets.

I ordered a new carb. Will update when it's installed.

Cturbo wrote:What modern carb will fit right on the KDX?

That's what I wondered. There has got to be several modern bikes that would easily swap over. If we could figure out which ones, we could source those on ebay etc.

There are plenty of guys buying aftermarket carbs for their newish bike.

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I went through this exercise several years ago. I avoided Mikuni carbs. I never did find a drop in replacement. There was always one or two dimensions that were off.

I will see if I can find my notes.

19Delta wrote:

Cturbo wrote:What modern carb will fit right on the KDX?

That's what I wondered. There has got to be several modern bikes that would easily swap over. If we could figure out which ones, we could source those on ebay etc.

There are plenty of guys buying aftermarket carbs for their newish bike.

Sent from my SM-G900V using Tapatalk

there are tons of 250/200 ktms being sold every day, I would imagine they would be the ones to compare

Please let us know all the details, I have same trouble, just cant get it jetted right, stays rich. Floats are right, changed the jet block gasket and still not right. Thanks for the information..

maybe it has an ignition problem.
the only corrosive part of modern gasoline is the water that the alcohol attracts. If it weren't for that water the main and pilot jet wouldn't wear.
The needle jet can wear due to contact with the needle.
My '89 KDX200SR had the original carb and there was no signs of wear on the slide. That happens when dirt is being let in past the air filter.

Jaguar wrote:maybe it has an ignition problem.
the only corrosive part of modern gasoline is the water that the alcohol attracts. If it weren't for that water the main and pilot jet wouldn't wear.
The needle jet can wear due to contact with the needle.
My '89 KDX200SR had the original carb and there was no signs of wear on the slide. That happens when dirt is being let in past the air filter.

i think you're right about the wear on the slide, and on the needle seat. mine was run with a partial (mice chewed it away) filter for undetermined amounts of time, without an airbox lid.

i'm updating in next post. jaguar, thank you, 100's of times, for all your contributions here. :)

I ordered a new carburetor from JetsRUs on tuesday morning, and it arrived the following saturday.

i started the bike with the jets the carb had:
168 main (yes, one sixty eight!)
68 idler
middle clip
1 1/2 turns out
fresh air filter
no airbox lid
STOCK expansion chamber + fmf arrestor

It would not idle. I didn't expect it to, but it actually RAN, with those very rich jets. my OLD carb would have loaded up and fouled a plug before i got out of the driveway, so this was an improvement !

I removed the 168/68 jets and replaced them with 148 /48 as a starting point.

the bike was lean at idle, slightly.

I remedied the slightly lean pilot jet by installing the airbox lid (yay for quiet!) and it was exactly 1 1/2 turns out for a sweet spot.

next i moved on to the needle. it bogged sligghtly at 1/2 throttle when i ripped on it. this was remedied by dropping the clip to the second from the bottom position, raising the needle one notch. bog was eliminated.

i moved on to the main, and did some wide openn runs. it's light biscuit tan, and i'm pretty happy.

findings:
bike lifts the front EASILY in 3rd or 4th, WITH the stock pipe and airbox lid.
bike idles endlessly, like forever. yes, it sounds great now instead of blubbery or odd. <<--- this part makes me very happy.
bike is so easily controlled in lower gears. in the past it was herky jerky, always wanting to RUN FASTER instead of just keep speed. now, i can creep in first gear without it being snatchy and annoying.

cruising down the road is SMOOTH. this bike has NEVER run this smooth before while at steady throttle. ever. never ever. this is THE BEST it has ever run.

summary:
my carb refused to respond from air screw adjustments unless there were LARGE input changes.
it refused to become lean at any jetting change, no matter how tiny the jets were.
it refused to consistantly idle.

the new carb was $176 shipped, and the BEST MONEY i've ever spent on a motorcycle.

stop fighting with your worn out pwk 33, and go buy a new pwk 35. it's worth every freaking penny.

today I ride for about three hours and used about a gallon of fuel, even with pig rich jetting (152/65) and did not foul a plug.

I can't wait to order some 50/52/54/56/58 and similar main jets and basil the jetting down like it should be. I pulled hills in fourth gear that normally required second out third.
hopping stuff was so much easier, smoother, totally predictable.

no more woowaaa woowaaa from using the clutch to sustain the poorer power.

this is awesome. can't wait to get more jets!

Man this sounds awesome. I may have to follow you. Thanks for the report!