Extended Fuel Screw for Hawk 250 and Jetting

[kwarb]

Wanted to let everyone know that the 2021 Hawk 250 stock carburetor uses a Keihin CV/CVK fuel screw. I have a 2006 Kawasaki KLX 250s and 2017 Kawasaki KLR650 which both have the stock Keihin CVK34 and CVK40 carburetors. The fuel screw in those bikes and the Hawk 250 is basically the same. What that means is that you can buy an extended fuel screw for a Keihin CV or CVK carburetor from Amazon for $10 and it will work with the Hawk 250. I will try to post 3 pics, never done it before so not sure what happens. If it works, one is of the Hawk fuel screw beside one from a KLX, one is of the Hawk screw beside an extended screw, and one is of the extended fuel screw on the Hawk.

Also, I got my bike a month ago. I know how to jet a carburetor well enough so no real issues for me, but let me share my experience with those who have never done it or at least never done this bike. I opened my carb before ever starting the bike to know what was in it. It came stock with a 40 pilot, 105 main, fuel screw at 1.5 turns out. No need to adjust anything so just closed it back up. Bike was not hard to start with the choke, but really really hard to keep it running until it was warm - it would totally die with the throttle at 1/16-1/8, but great if over 1/8th. When it was warm it was fine, except (1) it would die immediately if you lightly bumped the throttle for 1/4 second off idle and let off - though it would rev out fine if you held on and did not let off, and (2) it was burning plug tips white. Obviously way lean somewhere, but no issue revving it out. Since pilot jets do not really burn a plug, to me clearly a needle issue - FYI I ride trails mostly in the 1/4 throttle or less range. I put two 3mm washers under the non adjustable needle and the bike starts really easy, never dies, jumps off idle with a throttle twist, and it purrs like a kitten at 960 rpm idle speed. All bikes are a little different, but for new owners, I would shim the needle first before breaking the tamper seals on the carb. You only have to unscrew the throttle cable and pull the slide to shim the needle, but you may have to remove carburetor to get out the slide.

Hope I can help someone!

[China Rider 27]

Game changer for tuning the stock PZ30 carb and the PZ30B if it works well.

[wally]

Can verify, I use the same screw. It's a bit awkward to mess with it with gloves while the bike is running, but still possible.



I thought I had got the idea from another post on here but I guess not.


Here is the one I used from amazon:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


And in case anyone is tempted by the prettier one, I can verify that this one DOES NOT work:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[China Rider 27]

Good point! excuse the pun. The desire for something that might work got me to buy one of those a few years ago too, ha,ha. There are many offered for sale BUT it has to fit correctly, meaning have the the same slope down to a needle type point as the original. Good idea is to mark it at 1/4 turn intervals so you can determine your turns out or in. I bought one to check out.

[kwarb]

I looked hard for one of the pretty ones, they would be super easy to adjust on a hot bike. But the only pretty ones I could find are for the Keihin FCR carburetor - they will not work. If a listing does not specifically state it will fit a Keihin CV carburetor, the screw probably will not work on the stock Hawk carb. The Keihin CV carburetor is one of the most prevalent OEM carburetors on the market, so the seller would almost certainly state if it fits that model.

Performance wise, 1.5 turns out on the one I purchased is equal to 1.5 turns out on the stock screw. I cannot tell you if the taper is different at some micron level, but that only effects adjustment sensitivity and I cannot tell much difference. I tried to post a link to the one I purchased below.

https://www.amazon.com/dp/B098Q9S23S...roduct_details

[China Rider 27]

The one I ordered came in and it fits fine in the PZ30B I had laying around, the shaft diameter is very close, the profiles the same and the needle point is sharper on the extended screw. That carb had only a spring in it though no washer and rubber gasket, hmmm maybe that's why I could never get it to tune well. A washer and rubber o ring will definitely space out the adjustment as it seats further out. It sits right up against the bowl on one side so its not the easiest to use but still beat all the alternatives. Be nice to try when I use a PZ30 or B again.