Hey,

checked the plug on my '97 Warrior today and it's got a whitish tip. so i'm guessing it's lean. the only driving i've done on this spark plug is just around the house - aka. 10mins at no more than 1/2 throttle and 3rd gear.

before i work on anything i like to understand how it works. so what do the main jet and the pilot jet each control? what does moving the needle to a different hole do?

i did some searching and have gathered that the stock jet is a 145, correct? so a DG head pipe and muffler, plus 3 2" holes in the air box should mean i need what jets? maybe a 148 main jet? should anything else need to be changed?

many thanks,
bigmac

 

when i had amy warrior i think i found a 147.5 main jet . But i would check into a dynojet kit. it ran great as long as i was was racing. I didnt know about jet kits then so i just changed the main jet. You may be okay with just that though. I think the 147.5 was not a common size but someone had one.
Rudy

 

Hey,

i'm sure there's a reason for having a main jet and a pilot jet. so what does each control?

btw: thanks for the tip about the 147.5 jet. when you say "it ran great as long as i was racing", do you mean as long as you were WOT? what happened if you were just doing normal trail riding?

thanks,
bigmac

 

Hey,

after hours of reading old posts i found a link to this site on carbs and jetting

so here's what i think i've learned:

pilot jet/air screw - idle to 1/4 throttle - can screw in/out to adjust (or replace jet if adjusting air screw isn't enough)
- if located in the front of the carb, screw out pilor air screw to richen
- if located in the rear of the carb, screw in pilot air screw to richen
- adjust in 1/4 turns up to 2.5 turns, else replace pilot jet
jet needle - 1/4 to 3/4 throttle - adjustable by clip position
- lower clip to richen
main jet - 3/4 to full throttle - bigger means richer

and there's also something called a slide valve for 1/8 to 1/4 throttle. apparently comes in different configurations measured by the size of the cutout. smaller number means richer.

now the harder part is figuring out how to apply said knowledge. the above link recommends testing and setting the main jet first, then work your way down.

any comments on the above information? also, are all the above mentioned jets/screws reachable by removing the float bowl? any tips on ID's these parts once i take my carb apart?

thanks,
bigmac

 

Hey,

wow! i did all that research and nobody wants to comment?! for you guys who have fine tuned your jetting, what did you find to be the most effective?

also, is the pilot air screw different than the idle screw? my quad idles super low and is a little hesitant when you first let out the clutch in 1st gear.

so i'm thinking is should give the pilot air screw a half a turn or so, drop the clip one notch, and maybe a 148 main jet. or is that going to do too much?

will a larger main jet have any effect on 1/4-1/2 throttle leaness?

cheers,
bigmac

 

Try doing one thing at a time, to many variables could cause more probelmes than normal.

What are you running for a plug? cooler, regular or hoter?

As far as I know, the pilot is the same as the air or idle screw, i have never heard of one of each...

When you adjust you pilot, temporarily mark the carb with a marker so you can go back to where it was without guessing. then do 1/8 +/- turns to tune it in. (normally I mark full in and then back out according to that mark)

Changing the main jet will effect your midupper to upper throttle(wot) while moving the needle up or down will change the lowermid to uppermid.

so, if your problem is idling, its your pilot, if its mid responce it is more then likely a needle, if its top mid to wot, it should be your main.

Thats about what I know but Im not a pro mechanic or anything...

Im lookin at the dial a jet, you may want to check it out as well...

anybody else??

 

idle screw is located on outside of carb , follow your throttle cable. Pilot or air screw is located underneath the carb. I think the 147.5 is what i needed just needed to adjust the fuel screws some.
Rudy
will be tuning my raptor tomorrow , thanks for the info on different jets.

 

Hey,

i running the stock NGK spark plug (new).

the only driving i've done with this spark plug is half throttle around the yard, and the plug is showing lean. so i guess i need to try changing the clip position.

my yard isn't big enough to run WOT, so i'll have to find somewhere else to check and see if that's lean too.

just to make sure i'm clear about this, we're saying that the air screw and pilot jet are the same thing, correct? (thus meaning the pilot jet is adjustable by turning it) and that the idle screw is something different than the air screw? this seems to make sense to me. the idle screw adjusts how much air/fuel is going to the engine at idle, while the air screw/pilot jet adjusts the air to fuel ratio.

when you say the air screw/pilot jet is located underneath the carb, do you mean physically on the bottom of the carb, or inside the float bowl (which is on the bottom of the carb)? in similar words, do i have to take the carb apart again to adjust the airscrew/pilot jet?

also, is the air screw/pilot jet located toward the front or rear of the carb? this is important because it determines which way you need to turn the screw to richen the mixture.

i've got to go by the yamaha dealer tomorrow, so i'll see what the mechanic there has to recommend.

btw: always glad to share the info i find. hopefully it'll come in handy for lots of people.

thanks,
bigmac

 

The idle speed screw is the big gold **** located on the left side of the carbs by your knee. It can be turned/adjusted while sitting on the quad. The idle mixture screw is located on the engine side of the carb, on the bottom, and is adjustable without removing the bowls. The pilot jet (idle jet) is located inside the bowls, near the main jets. It is smaller in diameter and longer than the main jet. The pilot jet should be increased if you can't get a good idle-1/4 throttle response by turning the idle mixture screws up to 3 turns out.

All this is based on the Raptor carbs. Other carbs can and do vary according to position of the screws.

RR1

 

Hey,

thanks, that's very helpful info. helps me get things a little clearer in this foggy brain of mine, lol.

is there anyway to tell by the sound of the engine if it's lean or rich? like, if your at 1/2 throttle and then let off the gas quickly, should the motor pop? what does popping indicate? (rich/lean?)

thanks,
bigmac

PS: when i ordered a catalog for rocky mountain atv, the catalog showed up literally 1.5 days later. but i order a brake rotor and goggles from them and it's going to take over a week to get to me. what gives? bummer! lol, guess i'm just anxious to ride.