Attention all Jetting pros

[mopar1]

First off I have zero experience jetting a carb. I got my HMF and K&N put on today. I had been running stock everything until now. 145 main (I think), baffle removed from stock exhaust. I believe it was running lean ever since I've had it, but that's about to change. The 'basic' HMF jet kit comes with 3 'small right jets' (according to HMF's website). The site says they're 148, 152, and 155, even though the ones actually in the box are 147.5, 152.5, and 155. Anyway, the other day I stumbled upon the FMF website and their jetting recommendations and they were more in depth than the HMF specs. All the HMF site recommends is the 152 jet. FMF site says 42.5 Pilot, 3rd needle position, and 1.5 turns on the fuel screw, and remove snorkel.
1. Where is the fuel screw? I know the air screw is on the bottom of the carb. FMF says n/a on the air screw.
2. I don't see any kind of clips for moving the needle different positions.
3. Anybody got this similar set up? I'm all stock bore and everything, so no need to factor in any of that.
With the 152.5, it would idle rough and that was it, black smoke.
With the 147.5, it would idle really good, but any touch on the throttle and it will stall out, or stumble and bog. Sorry for the long storybook here.

 

[1998yamahawarrior]

No fuel screw on a warrior.

Start with the 147.5, 2 turns out on the screw and leave your needle position alone for now.

In tutorials theres a thread with a video on how to change the needle position if need be. My internets being slow otherwise Id link to it for you.

 

[beastlywarrior228]

148 and a 45 pilot, thats what ran best with my lid on

 

[elwood]

different air temp, pressure and elevation all play a role in jetting, and every machine is a little different, I would run it the beastly said with the air/fuel screw 2 to 2 1/2 turns out and then see how it runs and what your plug looks like. Then we can try to help you fine tune it

 

[mopar1]

I have the 147.5 in now. What about the little plastic bowl thing and brass washer? I think I've heard of some people leaving that off? I left it off.
Well, I'll try and see if I can find a 45 pilot. I guess I can go pull the fenders so I can get to the spark plug easy.

 

[Perry3182]

No need to pull the fenders, standard spark plug socket of the right size and a 3/8ths drive ratchet fit perfect.

 

[mopar1]

Hey beastly, did you leave your snorkel on? And one thing I forgot to mention was about the main jet. Y'all know how stock, the jet sits on a brass washer, and there's a plastic bowl thing that sits around it. The 3 jet O.D.s are smaller in diameter than the original 145 was, so the new jet isn't big enough to hold the washer on. The threads are the same, so I guess these are the right jets?

Still gotta get a pilot jet this week...

 

[elwood]

you don't need the plastic cup

 

[Hdale85]

Not my thread I know but I was curious since we're talking about jetting, would getting a custom put together kit like this be worth the 40 bucks or so? Says they custom select all the jets and needle and what not depending on your application instead of just doing the main jet.

http://cgi.ebay.com/ebaymotors/Yama...Accessories&hash=item35b3daac16#ht_2679wt_939

 

[elwood]

well you most likely wont need to change your needle, so you are looking at a few jets at about 4bucks each. Guess it's up to you. Personally I think jet kits are just a scam

 

[Hdale85]

Yeah that's probably likely.

 

[beastlywarrior228]

ya i had the snorkel on

 

[mopar1]

Well I think my biggest problem was leaving off the brass washer under the main jet. Runs ok now. The pilot jet is the one recessed into that deep tube next to the main, correct? I got a 45 from jets r us ($14 and some change, ouch) Somebody before me stripped it out and I can't get it to budge. What color should I look for on the spark plug to see how rich/lean it is?

 

[elwood]

14 bucks holy crap. I paid 4 at a local Yami dealer. yes the recessed one is the pilot jet. White is lean, black is rich and tan/brown is good

 

[mopar1]

Yeah, I probably won't order one again, I'll go to the dealer, but I knew they were going to have to order it too. My local Yami dealer is 30 miles away. The shipping was as much as the jet itself. Just got back from a test run, before I left the plug was black, so I'll check it again when it cools. I noticed at 3/4 to WOT it cuts out some.

 

[elwood]

3/4 to WOT is your main jet. you should change the plug each time to get an accuate reading from it

 

[mopar1]

Well, HMF did recommend the 152.5, but I still hate to think I've wasted 14 bucks since I can't get the old pilot out just to see if that would help anything. I did stall out at idle twice just then. I guess I'll be able to tell if the 152.5 is too big. A 150 jet would mean a trip to the Yami store.

 

[elwood]

any atv store should have jets, is there one closer than the yami dealer

 

[mopar1]

There's a Triumph/Arctic Cat dealer about 15 miles away. They do parts/repairs on anything though because they checked out my cousins Fourtrax 90 after he got in the pond with it, Lol.

 

[mopar1]

Well I'm slightly confused. The tutorial I read on here says if you have skipping at WOT, then back down one size on the main. I'm at 147.5. If I go down any more I'll be back to stock, and that doesn't make sense to me.