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Discussion Starter · #1 ·
i read a lot of post with jetting problems.
this is your Q&A we will help you if you have any jetting questions we have many hours, days, months testing on this bike and if we can help you we will.
first off here is a trouble shooting guide.
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1.. if you pop or back fire up towards the top end you are "LEAN"
2.. if it is boggy up top and has any black smoke on or out your pipe you are "RICH"
3.. if it is a rough idle your pilot is to big. ( or turn you idle up)
4.. hard to start pilot to big.(or pull the choke)
5.. if it boggs in the mid you are rich in the needle .
6.. if it is week in the mid and hit at the top you are to "LEAN" in the needle
these are a few diferent trouble shooting guides to use.
ok now what each jet /needle dose and works.
1.. pilot just for idle and just off idle. thats it.
2.. needle is for off idle/mid power.
3.. main jet is from the top of mid to the top.
4. fuel screw (because it a fuel screw not an air screw there is a big differance in this) don't mess with it, if you did it should be at 2 and 1/4 turns out. (unless you realy know what you are doing) you can through the whole carb off by messing with this and lose power quick.

HOW TO ADJUST NEEDLE.
if you are lean (week in the mid) raise needle
if you are rich (boggy in the mid)lowere needle.
i have new needles to try out on your carbs with a different cut to them that is suppose to make it crisper and pull harder i have not tested them yet.
FUELS
if you are stock or have minor mods (air box kit, pipe) 92 oct. runs great.
if you are mild built (piston or big bore) 92/108 border line.
if you are built (piston, cams,head work,porting etc...) 108/110
if you run avgas try not to thats a whole nother story.
if you insist on running 108 or higher jet for it you need to go up.(refer back to jetting trouble shooting).
READING THE PLUG
1... if it is white you are lean
2... black you are rich
3 on a 4 stroke you are looking for a clean burn with the makings of a golden browm look.
hope this helps
 

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Hi Green Lantern now I'm really confused first I hear that the popping up top meant that you were running rich. Now you tell me that I'm running lean when it pops up top. Now I'm thoroughly confused. When my bike was running rich it poped like crazy up top iI went down on my main jet and it stopped took some time to figure that my needle was set on the fourth notch from the factory or from the dealers set-up but once I figured that out I was in business. My bike pulls strong all the way to the limiter 1-5 with the occasional pop from the limiter kicking in but now you got me thinking topsy tervey. Help!!!!
 

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Discussion Starter · #3 ·
call me and i will go over it with you .
509 216-1849
 

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What time is good for you
 

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GREEN_LANTERN: You or some one needs to post pics on how to ajust the fuel screw. Thanks


later
 

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Discussion Starter · #6 ·
Hey Chilly,

It's not that its hard to adjust, but that it is very sensitive to adjustment and if you can't tell the difference between adjustments you have a good chance of making it worse.
 

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I hope you can help me here Green Latern, I put in the dynojet kit on my predator 700 ft above sea level with no air box mods and HMF pipe. I am running one size up from there replacement of the main jet and running the DJ needle at 2 and a half notchs down (i have the washer in there with the with the mixing screw 4 turns out.

Now here is why I am running it this way. With the needle at 2 notch and fuel mix screw at 2.5 turns out when I would gas it it would bog/miss/hesitate until the throttle was 3/4 or greater. Ok. so I am thinking I am rich on the bottom... move the clip down to the 1 notch miss/bog/hesitation is worse. Ok.. so I try moving down to the third notch.... Just like running 1 notch.

After playing with the fuel mix screw at 4 turns out and down 2.5 on clip the miss/bog/hesitation no longer present. Now I am wondering if I am needing to maybe try a new pilot jet 1 size bigger or maybe try stock needle.

Now the mj is running good dark tan color after running wfo down the trail to dead engine stop.so I think I am set there. I think I can get more powere out of the transition snappy from idle to say 1/2 throttle.

thanks for you help, Dan
 

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greenlantern I have a question for you. I ride at about 5000-9000 feet in alt. I have the uni-vents installed in my airbox and I have replaced the stock endcap on my exhaust, but still have the stock exhaust pipe. I had a 144 main jet that came stock with my preddy. after I installed the uni-vents, it would hesitate at the throttle and the plug was almost pure white after riding. I raised the jet to a 152 and now the hesitation has stopped, but I havn't ridden it since then, and havn't checked the plug due to not riding it yet. My question is, is going from a 144 to 152 to much of a jump? It sounds better than it did, but due to weather and work , I havn't been able to test it out yet! Thanks for your input!!!! Crypto...
 

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Discussion Starter · #9 ·
Hi Dan
if you can give us a call it is much easier to trouble shoot on the phone because we might be thinking differently when we are trying to explain the symptoms but i will try.
firs off is there a reason you don't have an air box mod? (it doesn't have to be ours) but the increase the air flow which this bike needs badly and the jet to it.
secondly most of the jetting problems i read about have some thing to do with that jet kit i have never run on so i don't know what they consist of.
now when you say you are running the needle 2 notches down dose that mean you moved the needle up by going 2 notches down on the rings of the needle?
give me a call and we can get it right .
509 216 1649
 

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Discussion Starter · #10 ·
Crypto,
you went the right way i don't know if its too big but here are a few things to look for the next time you ride.
if you go by the plug readings put a new one in and ride it for a while 30min or so normal then check it if you are getting a brown burn your doing good .
but set of the pants tuning if you are on it and in the top end it fells bogy or feels slower as you get in the rpm you are rich jrt down one size remember one change at a time you whan't to know what the bike is doing and how you got ther to many changes gets you lost.
 

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I race XC and there are some deep water crossings at times. I have rerouted the carb vent lines already. Due to the design of the air box putting holes in the lower portion would allow water into the air box. I am about ready to just go back to the stock needle and go from there. This is what I ended up doing on my 300ex when I got it. 2 nothes means I am running the clip in the second groove on the needle from the top. When is a good time to call you, remember i am a east coaster so try to figure in the time difference.

Dan
 

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Discussion Starter · #12 ·
we open at 10am and close at 6pm pcs time call any time
 

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what are the jets set at for stock???
 

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Discussion Starter · #14 ·
most Preds are set up with a 150 main .
 
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