Athena Big Bore Jetting - Yamaha YFZ450 Forum : YFZ450, YFZ450R, YFZ450X Forums
 
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post #1 of 14 (permalink) Old 04-12-2010, 05:54 PM Thread Starter
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Hi here folks,

had an engine seizure on my baby, well found also a very good deal off a quad mechanic down here for a complete engine with a athena 478cc Big Bore Kit.

My Set-up right now:

Athena Big Bore Kit
HMF Full exhaust sys
K&N air filter / airbox lid ditched
stocker carbs/stocker needle
running on
185 main
48 pilot
Needle 5th position

How`s that ? Lean or should I richen up a little more ?

Havenīt been able to find this kinda constellation in order to do a little recap, read through..

Another thing is I ain`t even runing the machine at idle for like 1 minute and the pipe gloves cherry red. I know its supposed to glow a little but not that much, concerns me somehow...

Give me a hand on this folks...any experience and idea ist welcome ;)

appreciate your help in advance...
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post #2 of 14 (permalink) Old 04-13-2010, 03:51 AM Thread Starter
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*bump *

anyone ?

I know this issues has been covered a couple of times but not in this constellation folks...at least I wasnt able to find the thread :(

Help me outta here, please...

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post #3 of 14 (permalink) Old 04-13-2010, 08:14 AM
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How many turns is your mixture screw at and what elevation are you at?sounds really lean on the pilot circut I would look for intake leaks if your header is turning cherry red that fast.I would also think about getting the ncvq needle and putting it on the 4th clip but that wont fix the idle issue.

2005 YFZ 450 XC
TCR adjustable exhaust,QC Porting,Falicon balanced crank,Oil mod,HC piston,Qs3,Dynatek cdi,K&N proflow/outerwear,Precision Pro stabilizer,+2 ars/fx stem,Rekluse clutch,Precision shock&vibe,custom Axis,Beadlocks/razr2's,XC dominator axle,14/38 gearing and (Fall/winter jetting)170,45pj,ncvq 3rd,2-1/2 turns.Blingstar & GT skids and Ars/fx xc arms
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post #4 of 14 (permalink) Old 04-13-2010, 08:48 AM Thread Starter
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mixture screw is at 2,5 turns & elevation 200 meters

what do you mean by checking intake leaks ... checking if it pulls any false air into it, basically not sealed properly enuff ?!?

Would it help if I set the stock needle to position 7th instead ?!?

The plug seems to be darkish grey, so im not sure if I would conisder it as fatal lean ?!
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post #5 of 14 (permalink) Old 04-13-2010, 10:38 AM Thread Starter
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give me a hand on this folks please :(
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post #6 of 14 (permalink) Old 04-13-2010, 12:43 PM
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start with a 180 main, 45 pilot, and the 3rd clip on an ncvq. To me you sean on the ritch side. Dont wory about the pipe. They all do that. It has a lot to do with whos pipe, material, thickness, and coating on the pipe. The color of the pipe is not good indication of how your jetting is

If everything seems like your in control, your not going fast enough
ITS A MMAD WORLD
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post #7 of 14 (permalink) Old 04-14-2010, 02:50 AM Thread Starter
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i`ll give it a shot with the specs ;)

If shes dies away, I`m coming up there :D *just pulling ya leg*
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post #8 of 14 (permalink) Old 04-14-2010, 09:11 AM
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i run a 175 main, 48 pilot, needle on the 4th clip, and air fuel screw in the stock position an it runs good. I am at 500ft.
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post #9 of 14 (permalink) Old 04-14-2010, 11:27 AM
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QUOTE (2strokebandit @ Apr 14 2010, 12:50 AM)
Quote:
i`ll give it a shot with the specs ;)

If shes dies away, I`m coming up there :D *just pulling ya leg*[/b]

come up, I need some one new to race the jetting should be close I think. the best thing to do it take to to a dyno and get it tuned.

If everything seems like your in control, your not going fast enough
ITS A MMAD WORLD
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post #10 of 14 (permalink) Old 04-15-2010, 03:10 AM Thread Starter
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185 main
48 pilot
Needle back to 4th position

seems to be running fine now lads ;) was concerned about the pipe but seems to be ok now...

Plug ist perfectly coloured and all good in the hood for now ;)

@Climb
That should be a easy race for ya with my baby having a engine seizure :D

Are u always picking out your oppoents like this


greets
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post #11 of 14 (permalink) Old 04-15-2010, 07:01 AM
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Great to hear your running.185 main still sounds rich but you may need to keep it till you upgrade to the ncvq needle 3rd--4th clip.Then I would start dropping the main till performance gets noticably worse then go up one size and you golden.Hows it start??When I went to the 48 pilot/3 turns, all I have to do is breathe on the start button and it fires up instantly.

I have to disagree on the statement every pipe turns cherry red.It has more to do with how your bike is jetted then the pipe MFG.The wall thickness and material of the header can be to blame,but why would you put a cheap thin walled POS on your bike. Sometimes intake boots develop small cracks that suck air in and lean out the mixture and cause headaches trying to get a good idle and spot on jetting.

Here is a great page on jetting if you havn't read it yet
http://quadhub.com/wiki/index.php?title=Rejet

2005 YFZ 450 XC
TCR adjustable exhaust,QC Porting,Falicon balanced crank,Oil mod,HC piston,Qs3,Dynatek cdi,K&N proflow/outerwear,Precision Pro stabilizer,+2 ars/fx stem,Rekluse clutch,Precision shock&vibe,custom Axis,Beadlocks/razr2's,XC dominator axle,14/38 gearing and (Fall/winter jetting)170,45pj,ncvq 3rd,2-1/2 turns.Blingstar & GT skids and Ars/fx xc arms
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post #12 of 14 (permalink) Old 04-16-2010, 05:20 AM Thread Starter
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Cheers Shooter,

runs fine so far no power loss whatsoever .. course havenīt been on the flat track yet but Iīll report as soon as I was ;)
where do I get the ncvq needle and what is the major difference btw ?!

Firing up is easy as eating a apple pie, I mean easy & instantly either ;)

regarding the "turning cherry red" I guess it defiantely has something to do thickness of the material ... I didn`t bolt that on it, was already installed ... Never mind looks kinda cool now when it gets dark outisde, now that I know its normal :D


Thx for the great read btw ;)
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post #13 of 14 (permalink) Old 04-16-2010, 11:33 AM
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QUOTE (2strokebandit @ Apr 15 2010, 01:10 AM)
Quote:
@Climb
That should be a easy race for ya with my baby having a engine seizure :D

Are u always picking out your oppoents like this


greets[/b]

that how you do it when you are slow as i am

If everything seems like your in control, your not going fast enough
ITS A MMAD WORLD
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post #14 of 14 (permalink) Old 05-12-2019, 07:47 PM
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Hello, bringing a thread back from the dead. Bought a YFZ450 with:


Athena Big Bore Kit
Dr.D Slip-on
K&N air filter with stock box


Elevation is 5000' but also will ride at 8000'

Pilot Jet is 45
Main Jet is 165
Starter Jet is 90

I'm getting some popping at idle but it seems to be ok once it's pass idle. I'm thinking it might just be the pilot jet that is too small. Should I go with the next up 48 or 50? I would like to get the correct jets for the entire range and also adjust main jet needle if need be. Could someone recommend jet sizes and jet needle setting? Thank you
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