Ok, so I ordered a k158 main jet. All the other mods are done, and I rode a dirty old gs650 last night that made me want as much gosh dang power as I can squeeze out of the 250. I also decided to get some custom earplugs so the noise factor is moot.

I am 90% sure I was achieving good fueling with the DJ 132 main jet, lidless and using the Dial a Jet.. but I wasn't going to be that guy that cooked his top end out of ignorance.

I've been running the 132 main, with snorkel removed. FMF q4 and powerbomb header. MCM Pulls right up to the 10500 mark, and I can squeeze 130km/h out of it. Not that I spend alot of time at this speed, but it's nice to be able to pass cars. I do believe the Dial a Jet is helping me, but all that hard work :P klxster has put into making his 250 scream is too tempting not to at least try. Heck, it's a 13.00 part....

I've also ordered new fork seals and bushings, as the front left fork is leaking. I installed the .46kg racetech springs, so the dive is reduced... but there is still a bit of stiction in the front end.

Another big breakthrough is my rear spring. I couldn't get the preload dialed in, even though I weigh 150 with all my gear (exactly what the spring is rated for). Turns out that the linkage installed was for a taller seat (ok since I'm tallish) but it reduces the leverage on the spring ie making it stiffer. Put the stock linkage back in and now it's properly cushy for my weight. Bike is getting closer to perfect each day, hopefully with new seals and bushings the bike will stop acting like a pogo stick on smooth roads.

Now to paint those plastics.....

 

I see what you mean by on to the plastics. New springs helped a lot for me on the road side and the cornering now is amazing.

 

I dont think anyone can help you as long as you have a dial-a-jet installed. Who knows how much fueling that is adding or not.... i have no idea how you would even measure it. You would have to take it to a dyno or get a wide-band AF meter installed.

Or IMO, ditch the dial-a-jet and follow klxster's recipe to a T. I will tell you that the 144/1N setup he came up with is a beast.

 

Nice that going with a Lidless setup is "drinking the lidless Koolaid".. That's what I've been after these last years - to make it common knowledge that HP/TRQ take a big leap with a properly fueled (dyno developed) lidless CVK setup..

 

Im not looking for help with the Dial a Jet. I no longer rely on internet strangers to correct my impulses. All Dial a Jet does is add fuel to a lean condition. If there is proper fueling, it does nothing. I wont be ditching it, as it doesnt overfuel. It also counters temp changes. Ie cold weather and more available o2. I dont see myself running over the Rockies anytime soon either so the k158 shouldnt be too rich for me. I run between Sea level and 1500 feet max

I will be purchasing a wideband 02 sensor/ AFR meter eventually, but in the meantime running a k158 1N stock spring lidless setup will be fine, since we have those numbers already. Im happy with my current jetting also, but tinkering is 50% of my hobby time so why not see what this 250 can do?

 

We are all lucky that my dyno shop had/has a properly functioning AFR module and that proper AFR testing methods were/are used.. Scootr's latest plug video is just another bit of evidence/testament to this - https://www.kawasakiforums.com/forum...j144-1n-44770/


I had no idea the AFR module and its' use could be problematic until we started seeing Houstons4's dyno data - his AFR data was obviously horribly wrong due to operator/module error.. After discussing this with "my" dyno shop, I fully understand how the AFR module and its' operation can create erroneous AFR curves..

 

How would a dial-a-jet know if you're rich or lean?

It's just basically an adjustable secondary main jet that works on vacuum like any other jet. I get the concept of leaning your main MJ out and using the DAJ to adjust back to running, giving you manual altitude compensation, but no... I can't see any way that a DAJ knows whether you're rich or lean and only works when you're lean.

 

I am not advocating the use of Dial a Jet or trying to sell them. I bought one with a complete dynojet 2125 kit from another user on this forum for the half the price of new.

If you have a genuine interest in how the device works, here is a link to the explanation. I can not articulate or explain it any better than how it is worded on the company website.

https://thunderproducts.com/dial-a-j...uction-system/

"Dial-A-Jet is an add fuel only device. You cannot add fuel to an engine that is running rich or has an adequate fuel supply and hope to gain horsepower. You must create a lean condition so that Dial-A-Jet has a window of opportunity to function. "

All I was saying is that I likely had good fueling (not lean enough to kill the engine) running 132 main jet lidless with the Dial a Jet. A 132 is a few sizes smaller than Klxster recommends for MAX power and AFR levels of around 12. I likely wasn't getting that low in the bucket but can almost guarantee the bike was not running above 14.1 (stoich) at WOT on the highway. I had no issues revving up into 10500 and it had alot more power (which is why I want the k158) than running 132 with lid on snorkle removed... again probably richer than 14.1. Either way, I took the road of caution and put the lid back on. Bike still ran great, just didn't have that crazy extra kick up top like before.

I am currently running DJ 124 with the lid on snorkel removed. There is a noticeable difference going from the 132, and the Dial A Jet is not making up for that power loss. I have it set to "medium" so perhaps richening the device would get it closer to the 132's power delivery. K158 jet should be here before next weekend, and I look forward to experiencing the power that I'm reading off the dynocharts available on this forum.

 

You unknowingly hit on the one point. It only works when running lean. If you ever ran a lean carb you will hear a heavy vacuum sound, there is both that and the acoustic wave patterns that cause the draw when lean. That is how the Dial-A-Jet works. It is another source of fuel, but not fixed like a needle/needle jet/main jet. The instructions are to jet to optimum, then back down two jets leaner. That allows the Dial-A-Jet to feed the added necessary fuel. That allows for temperature and altitude variations to be compensated for. Plus the five step ability to vary the Dial-A-Jet in should there be necessity without tearing half the bike apart.

As said it is like Mikuni's own Power Jet but actually adds atomized fuel mix, not just raw gas. If Mikuni could do it all with one jet they would not have made the Power Jet. Plus brass is limited by physical shape, which can cause flat spots. So a small fuel adder does the trick to supplement the flow to smooth flat spots and optimize mix.

Go to the site and read about it. I did back in 1985 when they came out. I was sold by performance on my Nighthawk S and my KLX650 over a 20 plus year period of using the Dial-A-Jet. It isn't a total substitute for rejetting, it is a way to not have to rejet for altitude or temperature, to smooth out lean spots. I didn't have to take the carbs off the lean jetted Nighthawk S or the lean jetted KLX650, the Dial-A-Jet was sufficient to do the job for both. On the KLX250 I don't have the tools and gauges to deal with the fuel mix so I went with the known KLX300 jetting, because my brother did it and found good results.

My brother installed the Dial-A-Jet in his bike after having run the 300 setup and found it smoothed out the power delivery for better performance. I put it in at the start with a shimmed needle, drilled air jet, and no main jet change (if I remember right). It wasn't enough, so I jetted up and put in the adjustable needle, but went leaner on the main. Similar performance on the two bikes, I'm just heavier than him. No surging, which was still there with the shimmed needle.

If I had done the 300 jetting slightly lean the first time I would not have had the carb off twice. That is the one benefit. The other is the ability to do some additional tuning with the five mix positions. If I went up over 5000 feet I might be fine just leaning out the Dial-A-Jet as long as the brass is lean enough. It doesn't work the other way though. The reason why the instructions say to drop two main jet sizes. That provides a leanness to have the product work.

Don't believe me, Dick's Racing does carbs using the Intela-Jet and Dial-A-Jet, MXA and Motorcyclist did some reviews, and the snowmobile and ATV media also have done some tests. The company isn't big enough to have any marketing sway, so the reviews are pretty honest. Plus a 4.5 star rating at Rocky Mountain ATV & MC. ATV and snowmobile community is newer and more open to new ideas, this is one they took up that the motorcycle community didn't.

Take it for what it is worth to you. I know what it has been for my use.

 

Well said klx678.

A question for Klxster, in the link on your signature to dyno tuning with full fmf exhaust, I see you tried it with the 132 main 4n and had results that were not in the danger zone ie above Stoich. Only with the DG pipe and stock header was there a curve above 14afr. FMF danced around the 13 afr mark... This was the best AFR for power on my wr250r when tuning with the PCV and Autotune. For some reason I missed this detail beforehand... I wasn't at risk of cooking anything with a 132, especially with fuel being added at any lean point in the curve via Dial a Jet.

Now I really want to try the k158, with dial a jet set to leanest setting (least fuel added to a lean condition) then try a k152 with the dial a jet set to medium and see if there is a better throttle response, or even the same top end power with better midrange. All speculation at this point, but worth the time and effort