What Carburetor for 2004 - EC250
 

Hi team
My EC250(2004) old carb was having some issues, tried to repair with repair kit but no luck. Fuel consumption was double the average and smoked a lot.
I bought a Keihin PWK 38 airstriker carb to replace the old one, but I suspect this is not the correct carb for this bike.
When I installed it new, it improved fuel consumption, and smoked a lot less, but I experienced following problems:

the idle was super hard to stabilize, whether too high or too low to the point it stalls.
Bike tended to get hotter when in the trails to the point of water boiling sometimes(never happened before)
In lower rpms it lost most of the power, I needed to clutch a lot when doing technical sections or when trying to get out of a heavy hill or something.

So I came to conclusion I bought the wrong carb. I noticed there is a Keihin Quad vent and Keihin Airstriker, not sure if any other out there. Wondering if you can help me determine the correct carb for this bike, ebay link will be of help so I can buy it.

Note; I took a friend's husqvarna 300TE(2016) carb put it on my bike and worked smoothly.

Sounds like it needs jetting,and float height set. the carb is correct. Quad vent and air striker are the same. Or so I'm told.

Are you sure it's a genuine Keihin carb that you bought? Many cheap/poor quality carbs out there for sale.

As far as I'm aware... Keihin PWK38 is the correct carb for your bike. AirStriker Quad Vent is correct.

Like John rb says... Sounds like it needs jetting, but first check/adjust the float height. I would only use genuine Keihin Jets.

Can you copy the jetting from your friend's carb? It might not be perfect but should get you somewhere near.

Loads of information regarding jetting on this forum.

Good luck, Dave.

Someone please correct me if I'm wrong...

There are 2 versions of the Keihin PWK38 Quad Vent Air Striker carb, the AS1 and AS2.

The AS1 fitted to earlier bikes and the AS2 fitted to later bikes, they're very similar carbs.

The AS1 has a black 'screw on' top...
Attachment 7778

The AS2 has the top secured with two screws...
Attachment 7779


Your 2004 bike should have the AS1.

Where do you live? I can recommend this shop based in Holland (they ship worldwide) for Genuine Keihin new/used carbs and spares:

Frank MX Parts https://www.frankmxparts.com/

Hope this helps, Dave.

It doesn?t matter which one you have. Both of those carb will work just fine.
Check the above mention.

Jetting
Float hight
Air leaks.

What is the difference between those 2 in terms of bike performance?

I am afraid I bought a cheap one(china) and that is why it does not work good

No difference, they work the same.
Round top = older model
Rectangular top = newer model

My later model AS2 is shorter in length so I had to machine up an adapter. It was off a 17 so not sure if earlier AS2 are the short type.

There's no difference in performance between the AS1 and AS2, both will work great on your bike...

BUT it's essential to get your carb setup correctly, or it won't run correctly or may not even start at all!

Start with the basics, clean air filter, good spark plug correctly gapped, new fuel with good quality 2 stroke oil (usually 2% for full synthetic but check). Check rubber tube between carb and reed block, on older bikes the rubber can perish and split causing an air leak, it's not expensive to replace.

Then check carb, remove main jet and pilot jet, inspect/clean. The hole in the pilot jet is very small and can easily be blocked.

Remove float and float valve, clean/inspect. Rubber tip on float valve can look OK but on older bikes the rubber can harden and it doesn't seal so well.

Check float height, very important before you start adjusting jetting.

Once you've completed all the above start trying different jets. You said it ran good with your friends carb, try copying his jetting, it might not be perfect but should give you a good starting point.

Main things to concentrate on are... Main Jet, Pilot Jet, Needle and clip position, Air Screw.

Good luck, stick with it. Once you get it jetted correctly it'll be a great ride! :)