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long beach, ca
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Most of you agree there are THOUSANDS of some type of "jetting questions" on the Org....

This is usually about as close as your gonna get depending on other issues. If you find the Fuel screw at less than ONE turn out from lightly seated position (go with next size SMALLER slow jet), and if out more than THREE turns, go with next size LARGER main jet. Then start this procedure over until the fuel jet is adjusted correctly, and it falls between 1 and 3 turns out from seated. this adjustment is usually performed in the garage.

i dont mean to ??? you on this but i sure am confused when you say if i am out more than 3 turns on the fuel screw i need to bump up my main jet.. as i understand what you wrote the main jet is for wide open throttle and the fuel screw is for basically closed throttle or so..

any way
07er
175 main
145 pilot/slow jet
boyesen qs3 turned 1 turn out
fuel screw 3 1/4 out
sparks exhaust
k&n box lid filter
it ran great accept it sounded like a machine gun going down hill closed throtttle. the jetting is what sparks sends in there jet kit. the needle is in the middle.
thanks ralph
 

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2007 450er. Has FMF Mega bomb titanium head pipe with FMF Q4 muffler, uni filter stock box and approx 20.... 3/4" holes drilled in the lid. Have stock lid I can put on. Green wire mod, MSR fuel mixture screw, and FMF jet kit. Running between 1600-2000 elevation. I just put the FMF stage 2 jet kit in (per directions) and the quad now bogs under heavy acceleration between idle and 3000 rpms or so. I am now seeing how hated the FMF jet kit is on this site so please help me out. I will order whatever jets are recommend and try them instead. I am no professional with carbs as I usually run FI machines. Any help or advise appreciated otherwise I will have rossier engineering tune it as they are 50 miles from home.
 

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Also if the quad is idleing and the throttle is mashed in neutral it bogs. So not just under load.
 

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500R
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Also if the quad is idleing and the throttle is mashed in neutral it bogs. So not just under load.
Only buy OEM Keihin jets man... all other brands are inconsistent and not worth saving a few dollars in the long run.

Take the air box lid off, and leave it off. This will make jetting easier and more predictable. If you really want to keep it on, I suggest cutting it in half.

Install a #162 genuine Keihin brand Main Jet.

Install a #42 genuine Keihin brand Pilot Jet. (this is the stock size pilot jet, so if you've never changed it you're good to go) Set the fuel screw at 1 3/4 turns out from all the way in, LIGHTLY seated.

Purchase this needle. It is the correct one for your application. Use the middle clip position. You can also get it from you local Honda dealer. http://www.partzilla.com/parts/detail/honda/HP-16231-MEN-671.html

This should get you very close, if not spot on for jetting. Check and make sure the carburetor is clean while you have it apart. Make sure you have fresh, premium fuel. I would also go ahead and install a new NGK IFR8H-11 Spark Plug while you're at it.

Good luck.
 

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07 trx450er
two brothers racing vale full exhaust system m7 aluminum
has different jets than stock but I don't know what brand but it has 180-45-75 jets
air box lid is off and it has a huge air filter on it
top end has a fresh rebuild


I don't think it has the right jets in it. please advise what I should have in it
 

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450R Rider
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983 Posts
Whats a good starting point for 04 501?
43.5 bored FCR
Ported +1 OCP Head
+3mm stroker crank
+3mm 97mm CW cylinder
13:1 CP Piston
Webcam 208
Dasa Intake on stock 04 tube
Dasa Shorty exhaust
Elevation=200ft
Running on VP110
 

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373 Posts
Only buy OEM Keihin jets man... all other brands are inconsistent and not worth saving a few dollars in the long run.

Take the air box lid off, and leave it off. This will make jetting easier and more predictable. If you really want to keep it on, I suggest cutting it in half.

Install a #162 genuine Keihin brand Main Jet.

Install a #42 genuine Keihin brand Pilot Jet. (this is the stock size pilot jet, so if you've never changed it you're good to go) Set the fuel screw at 1 3/4 turns out from all the way in, LIGHTLY seated.

Purchase this needle. It is the correct one for your application. Use the middle clip position. You can also get it from you local Honda dealer. 16231-MEN-671 NEEDLE SET, JET $16.97

This should get you very close, if not spot on for jetting. Check and make sure the carburetor is clean while you have it apart. Make sure you have fresh, premium fuel. I would also go ahead and install a new NGK IFR8H-11 Spark Plug while you're at it.

Good luck.
Thank you sir, this just helped me out. I see I'm probably pretty rich with my new setup at a 172 main, gonna go down to the 162 to see if that helps.
 

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Performance Upgrade Wanted

05 450r completely stock with stock air filter and air box.

Looking to eliminate the bog I get from the bottom of a hard acceleration and a performance upgrade. I'm willing to re-jet or do an air box mod, all the way up to buying a new exhaust system. I just need a good starting point. Any help will be greatly appreciated
 

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I have a 2014 trx450r and need a little help with jetting
Mods-
FMF PowerBomb Header / Exhaust
Uni Air filter
Air box lid on
I ride at 0-1000 altitude
122 main jet
42 pilot jet
Stock needle
It pops on deceleration
Is it lean ?
What should i increase size in
Increase main jet ? Or pilot
Thanks in advance
 

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2,345 Posts
Any main reason why the air box lid on? For the 06 up I at least usually cut them to be like an hrc lid and will help give it more power. If the box was off I would start with a 45 pilot, might need to go back to the 42, 2 turns out on the af acrew, 162 main, hrc or ncqv needle 3rd clip and 55 leak jet. I am around 500 ft usually and that is a decent starting point for a full exhaust and open box setup.
 

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Jetting

2007 trx450er
Hrc cam 14110-nlz-610
Full rossier exhaust
Modded lid
Uni filter
At sea level (Florida)

165 main
45 pilot
55 leak
A/f 2 turns out
Ngpr 3rd groove down
No bog, punch from a stand still it tries to throw you off
 

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any jetting suggestions for an 08 trx450r after installing an ROBL intake?
the previous mods were/are:
HRC kit: Cam, 162MJ, 42 Pilot, etc.
air lid off W/K&N filter
Dasa Exhaust
 

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Should i go with a ~178MJ and ~50 Pilot?
 

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450RR...your mailbox is full.

Ok folks...I am stumped. 2005 TRX450R


I'm wondering if you can help me out. I'm having a heck of a time getting this bike to run right.

A little background on me: have had a series of Honda quads, did desert racing, then got into buggies. Relocated to Reno, and saw this little gem. Has almost zero ride time.

Anyways, i took off stock suspension, bars, ec. And put Upgrades on it. Bike ran extremely well in stock configuration. Opened up rear half of airbox lid, like HRC kit, Pro Design foam filter, and put in a FMF/Dynajet jet kit (170 D main, pilot screw 2 turns out, Dyna needle 3rd clip). Stock exhaust, fresh 91 octane gas. Bike was an absolute bitch to start. After chasing various things, I went back to stock 118 Keihin main and needle, and drilled out the air stop; bike starts right up (kicker).

Well, when I put the bike into gear, it bogs right off the idle and stalls. Since it felt like the clutch was slipping, I redrained transmission, pulled the clutch and inspected. No wear on basket, and all plates look great. Put it all back together, and still have same problem. When the pilot screw is at 1 - 1 1/2 turns, bike starts easy, opening up to to 2 - 2 1/2 turns, bike becomes hard to start.

I'm about to replace the lid and carb, can't believe this is plaguing me. My old 05 TRX450R was so reliable, and many more mods; always started easy.

I'm at 4000 ft, air temps are currently 70-82, bike has rear half of lid cut out (aka HRC), stock exhaust, pro-design foam air filter kit. Motion Pro twist throttle, all cable free play for throttle and clutch are within specs. All electrical is good.

Appreciate any help you can give.

Thanks,

Curt
 

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I have a 2014 trx450r and need a little help with jetting
Mods-
FMF PowerBomb Header / Exhaust
Uni Air filter
Air box lid on
I ride at 0-1000 altitude
122 main jet
42 pilot jet
Stock needle
It pops on deceleration
Is it lean ?
What should i increase size in
Increase main jet ? Or pilot
Thanks in advance
I have the same exhaust and i am at 3300ft and it pops and sputters as well. Im assuming i need to move up in jet size. All stock just uni filter and fmf powerbomb full exhaust. Should i over jet because of exhaust and filter or put in the exact jets for my altatude?
 
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