I've been jetting my bike, trying to dial it in to my mods, terrain and weather. Last week I was at a 152 main, 48 pilot, stock needle and 2 turns out. So I got an adjustable needle (7 position NCVT) on the 4th position, same 48 pilot and 152 main. Bike ran the best it ever has w/ no bog off idle except there was a small sputter/gargle @ 1/4 when just putting along. So I knew it was running rich, so I changed it to the 5th position, 48 pilot, and added a 165 main. Installed those lastnight, started the bike, played w/ the fuel screw and idle for a min and thought it sounded ok. Got out to the woods today and I stalled the bike, alot. It was running fine, maybe a hair of bog, maybe just from the screw, but running good. But when I stalled or just stopped the bike, I couldn't get it started. It was a nightmare to start allday. I knew it was the idle and fuel screw, I just couldnt get them dialed out there for some reason. Bike was so hard to start. As I turned the screw in, it got better. I think I rode most of the day on 1 turn out w/ a good idle, but still not that perfect hum. I got home and played w/ it some more. Finally, 3/4 turns out, idle adjusted w/ it, the bike starts right up everytime w/ half a push of the button, runs and idles perfect, no bog, gargle, nothing!!

My question is, if the fuel screw is less than 1-1/2 turns, that means my pilot is to big right? Is it on to run it as is or do I need to try my 45 and 42 pilot jets so that I can get it to about 2 turns out? I forgot, is turning the screw in (lean) and out is (rich)? Is this why I had to adjust it so far in because I'm so rich on the pilot? I guess the needle fixed the lean condition and I should be able to go back to a normal 42 or 45 pilot @ 1-1/2 to 2 turns out.

Your pilot and main may be too big. I thought you were on a 450x, sorry. 45 pilot and 155ish main should be close.

Yea it was running good w/ the 152 main, but JD kit said run a 165 w/ the mods and needle i have. I'm gonna try the pilot 1st (45) and see what that does. It seemed to rev higher w/ the 165, so the main felt right. Its fine now @ 3/4 turns out, but I know its not supposed to be less than 1 turn out and most people said this bike needs to be @ 1.5-2 turns out. Well see!! But yea, I thought a 155-160 tops would've been good since the 152 was there already...

A couple of things:

1. The JD needles are different then the NCVS, so you cannot look at a JD kit and use the same main/needle position they recommend with the NCVS needle. Check the forum stickies at the top of the fourm to see what others have used with the NCVS needle.

2. Keep in mind that the pilot, needle, and main, all tune different areas of the throttle range. (Pilot closed to 1/8, needle and main 1/8 - approx 3/4, and main wide open).

3. At 3/4 of a turn, your pilot jet is too big. Turning the fuel mixture screw in reduces the amount of gas that can get to the engine (your putting the needle farther into the hole). If you turn it in till it "seats", you've plugged the hole. Conversely, if you screw it out all the way, the maximum amount of gas that can get to the engine is determined by the size of the pilot jet.

A smaller pilot jet would get you closer to the middle of the range on the fuel screw (which is 0 to 3 turns out), but if you don't ride in different areas and it works fine as is, there is no "requirement" that it be at 1 1/2 turns out. I'd leave it as it, although getting to a perfect setup would give you better adjustability and a little more range to adjust if conditions change.

Right now, turning the needle only a little bit will make quite a change, where if you had a properly sized pilot, you would not find that so much so.

4. Finially, don't forget that you also have the accelerator pump circuit. This dumps a squirt of gas into the engine when you wack the throttle open.. So first, get the bike running well with smooth throttle changes and don't worry that much about bog or hesitation if you open the throttle suddenly.

Once it's running well, if you do have a bog or hesitation, then you'll want to go DOWN in size on the leak jet. This is opposite the way the pilot and Main work (larger is more gas, smaller is less).

That's because the leak jet leaks gas back to the carb, making less available to the AP to squirt, so if you go down, there is MORE gas left for the AP. If you go bigger, more leaks back to the carb and there is less for the AP to squirt. Again, the stickies at the forum top are your friends<g>.

HTH,
Jim.

Thanks Jim. I've got another question. My 152 main seems to run the same as the 165 main. How do I know which main to choose?

I went back to the 42 pilot today, 165 main and clip on 5th. Now the bike seems to have a little bog off the bottom again. I'm having the same problem, the bike is a nightmare to start. Only seems to work best @ 1 turn out. What is it I'm missing? Is my main to big? Since I put it in, the bike wont start hardly. I'm charging the batttery tonight to make sure I didnt drain it anf thats the problem. Any ideas?

I'm gonna just put it all back to where I had it last weekend and it was almost perfect, just had a little gargle @ 1/4 throttle (rich condition)
152 main, 48 pilot, and the needle on the 4th position. The bike ripped w/ this more than it ever has all over except when I was just crusing at trail speed (1/4) throttle it had the gargle. I think I should just play w/ the fuel screw at these settings to try to get that out. At least the bike started right up and ran like a tractor

Try that setup with a leaner clip position.

I did, fired right up w/ no bog. I was adjusting the idle and fuel screw to try to get it peferct but somehow lost my count and which way to go on the idle and thats what messed me up. Wont start now. My idle and pilot is off. Gonna take some tinkering again

Screw idle adjuster in 1 turn. Back the fuel screw out in 1/2 turn increments until it starts properly, then(once warm) adjust fuel screw for current pilot (plenty of threads on this ). Adjust idle /and fuel screw for approx 1800 rpm. Basically, turn fuel screw in until rpm drop, then back off 1/4 to 3/4 a turn(listen for rpm drop). Slightly rich on bottom is probably better than lean. Lean on bottom means hard starts and low throttle bog.

Dang , forgot to ask , were you using the hot start lever? My 450 likes the hot start lever when warm out with warm engine.

Yes. mine does to it seems like. That always helps, sometimes I even have to choke it. I've got a new batterry and I recharged it again. When the jetting is on it fires right up...

I finally figured it out and I knew it was gonna be the simpleist thing that I over looked. When I was finally getting the bike started it was running super rough and real smokey. This bike has never ran like that and I couldn't understand why the same jetting that worked so well would now make the bike run super rough and not stay running unless I was twisting the throttle. I finally checked the plug, even though it is a month old and one of those $17 NGK's. Black as hell. Also I checked my oil 1st and it seemed low and super black on the kick starter side.. Not sure what caused it to be low and so black. I change my oil every 100 miles and it always looks brand new when I change it. This time I let it go to almost 200 for whatever reason. Anyways, then I checked the plug and its fouled like hell. It didnt't even cross my mind because of the 3 thumpers I've had in the past year, I put a new plug in each of them around the time of purchase and never looked back. Do you guys know how & why a 4s fouls a plug so bad? I'm still learning w/ these bikes as I've only been riding and working on them for a year now. I'm sure after I put a new plug in it tommrow it w/ fire right up and it w/ be easy to set the fuel screw...

You are probably rich somewhere! Needle or pilot more than likely.

I wonder if it was that 165 main I put in this weekend. I put the 152 back in because I know it works good. I've got a 155 on the way, which I think thats as big as it will go. I had raised the clip to the 5th when I put the bigger main in, but I went back to the 4th. New plug tommrow should do it, everything else is good..

Quote

Clip positions are numbered 1 to 7, top to bottom.

Thanks, so moving the clip to the top (towards the point) richens it?

Sorry, I meant raise the needle and lower the clip. Thats what I meant and did.

Quote

The top of the needle is blunt and the clip position is number 1 and lean.
The bottom of the needle is the point and the clip position is number 7 and rich.

GoonSquadRMZ450, on 15 February 2012 - 07:59 PM, said:

Oops - I think I might've clicked an 'unlike' button - ignore it if it shows up somewhere...

You say that you keep switching back and forth between a 42 and a 48 pilot, when you know a 45 is right (I suggested that to you months ago). Put in a 45 and don't listen to anyone else. It will be just right. I also suggested a 155 main, which also seems to be where you are ending up.

It sounds like you swapped back to Honda needles from the JD needle - the JD suggested main is only valid with his needles - they seem to require significantly richer mains - must be longer than OEM or something.

In my experience, the stock needle is fine, it just needs to have the clip dropped a couple of notches. I am running position #5 (stock is 3), although a 1/2 clip shim would be perfect because I am just a hair rich on the needle. A 1/2 clip leaner or richer needle would serve the same purpose.

I see that you have experienced the real value in JD jetting. Bet you won't do that again .

JayC

Its all good. I wanna learn how to work on my bike, especially the jetting I think its important to know how to do it yourself since the weather and altitude affect it so much and even the fuel screw through out the day. At least the simpler aspects of jetting. My stock needle has 1 position. One of my friends gave me a 7 position needle so I could fine tune a little more and the bike rips alot harder just with the new needle alone. So I out that in and I had to try to adjust the jets w/ that as well as the free mods I've been doing in stages. The 48 pilot was the best one for my bike. Not a hair of hez or bog, I loved it. The 42 and 45 still had the bog no matter what I did with the needle and fuel screw. So thats why I went back to the 48 because I knew it ran the best w/ my bike. My bike was great w/ the 152 main in, but I removed the screen and baffle all together, so my JD Jet Kit sheet said go to 165, so I tried that. It didn't work, fouled my plug. Were I messed up was going by the JD jet kit specs. All the bike needed was to be tweaked with the fuel screw w/ the 48, 152, and clip on the 4th because it ripped w/ those jets, there was just a gargle at 1/4 throttle. I had it almost perfect. but when I got that sheet w/ the needle it through me off.

Test run the 48 pilot with a leaner position on your needle(RAISE CLIP).