can some one answer this...

would it help to have a smaller valve clearance for my intake valves ..
the idea is less air will get in but the same amount of fuel will go to the piston.

also since theres two intake valves ...do they both let in a mixture of fuel and air or is one fuel and one air?

 

Your air fuel mix is blended in the intake and enters in both valves. Valve clearence will not effect valve lift from the camshaft lobe. Valve clearance is only a few thousandth of an inch and only there for heat expansion.

Btw the air injection system makes the poping worst. I have my bike jetted with injection removed and have zero pop.

You need to atleast remove the air fuel screw cap and open the mixture screw out a turn or so. 3 turns out from seated is a good starting point.

 

I got nothin' for you anymore. I think you should have someone do the work for you, you're giving every indication you probably should not do the work.

If you truly want to know what is going on, go do the research. Go to the Mikuni and Kiehin web sites and read about carburetion. Mikuni is really good on that and they all work pretty much the same. Do some research on motorcycle carburetor jetting. You will find a lot of forum discussion as well as some reputable sites for information. There is one member here who has a lot of information on the carb using Dyno Jet stuff. Look up some of KLXter's posts. He has DJ kits down pat and has done the AFR tuning for himself.

If you want the simple way out, go to the link for KLX250S cheap mods in my signature and do what they have there. It has been tried and true to get darn close to perfect since 2006, the guys did the work when the bike came out and nothing has really changed since then.

 

The easiest way to fix the fuel/air % would be for you to get a FI unit and put it on your bike, then you could forget about it forever.

But be sure that the left valve is set correctly or it will mess up the air turbulence in the combustion chamber.

 

ok well. thats your opinion ...im just trying to avoid fking it up, im not a professional so I want to learn before doing it.
I was considering buying a new carb .. cause i don't mind spending the money. I'm just here to get your advice to supplement the research I do surfing the net.

what exactly is "dyno jet"?

honestly i think all I need to do is re jet the carb is adjust the screw.

I think the main jet is fine
I think maybe I could get a slightly larger pilot jet? maybe 1 size up
maybe its fine because I increase the pilot maybe it will run too rich at idle

it does not pop on idle ... only when slowing down (deceleration)
what do you think?



I think your'e mis interpreting Im not asking for the cheapest fastest solution I'm just don't want to blindly approach the issue then cause another issue that I have to fix, then another and another...
thats what I meant by one easy fix

 

so adjusting the intake clearance won't have affect on the intake mixture? whether it is "looser or tighter" within spec..?


I think approach I might take ,is install the EPA thing and to compensate for the extra air ..jet the carb by maybe increasing the pilot jet size or just adjusting the screw.
idk what if the carb was getting old .. do you think it could be bad vacuuming? ... I looked at the carb and the thing looked very clean so maybe its just not sucking enough fuel properly.

 

Dyno Jet is the brand of jet kit. Changing the idle mix screw only changes the mix from idle to about 1/4 throttle with the throttle slide coming in progressively from there along with the jet needle. So you see, to do the job for the best performance you should do it all.


Look here for more information from Sudco. They have been around since at least the early 70s.

If you read what I've written you would know turning the screw in clockwise if you could look up at it will lean the mix out. Turning it counterclockwise will richen the mix.

For the proper idle mix short of fiddling with AFR instrumentation people who know what to do will:

• turn the mixture screw out until the idle starts to drop (Honda uses idle drop for carb balancing, so it is a legitimate method to do this), If it goes beyond 3 rotations, the pilot jet is too lean - the stock one is too lean. You need a .038 or .040 pilot jet.
• turn the screw back in counting the turns until the idle drops again.
• Divide the number of turns in half, rotate the screw that far back out and the idle mix is darn close to perfect, only instrumentation will get it closer and that will only be for the weather conditions of a given day. AFR varies due to temperature and humidity along with elevation.

That will get the idle mix correctly adjusted.

If you just take the time to do some reading up on the modifications others have learned about, I collected the bits in the link in my signature for Kawasaki/Kiehin parts, you will find what works. You will also find it makes sense when compared to information from Sudco.

I also have enough experience to know the KLX needed jetting changes to run the best and I went with the Kawasaki parts because my brother had just done it according to those part numbers and it worked great. I didn't reinvent the wheel to do the job, because they already did all the time consuming jetting changes to arrive at the specs they had and it has been used by numerous others.

There it is in a nut shell or at least a couple web sites with some reliable content. I am not a professional mechanic by any means, I've just learned enough to do what is usually needed. I learned jetting the way you are right now, difference is I had the guys there with me and we did it instead of going back and forth. Back then the guys were all about main jets only (flat trackers, go figure). Some said Bultacos and Maicos just wouldn't idle, they were just too high a state of tune. I bought that until I learned about pilot jets and changed my pilot jetting. My flat tracker would sit there and idle all day long. My friend got a Maico, we swapped out for a leaner pilot in that case and had it idling just fine. Amazing what one learns when one just does it. Follow the recommendations and you will not screw anything up. Go off on your own at your own risk.

If you can do your valve adjustments the carb is no big deal, it's unscrewing stuff and putting other stuff in. The only touchy thing is doing the starter jet if you do it. Use a pin vise and do it by hand. Otherwise it's just turning wrenches and screwdrivers. I was more intimidated by the valve shim adjustment and found that to be a breeze too.

 

Correct! The clearance has nothing to do with air fuel mixture at all.

Too tight and you have hard starting when hot an ultimately burn a valve. Too loose and it sounds like a coffee can full of nuts banging around.

Focus on the carb. It's the only issue a Klx has.

 

Install per directions according to what mods your bike may or may not have and call it a day.

https://www.rockymountainatvmc.com/p/2898/23954/Dynojet-Jet-Kit?v=6976

 

I apologize for not being here sooner - seems I am still needed here for helping.. Kinda a shame..

Horror_fan, If you will read my dyno tuning threads, you will see that I have worked out the proper max performance tuning for several mod combos on the dyno..

See the threads below, in my signature line..