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Discussion Starter · #1 ·
Hi, I have stock jets on my trx450r 2006. little hard to turn on but it works and accelerates just fine. but its backfiring on decel ? { I have uni filter, open air box and stock pipe.2 1/2 turns out fuel screw and im in san diego @ sealevel.} What jets would u guys recommend for my set up? please
 

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Backfiring on deceleration is caused by a lean condition - the FCR carb does not have an air cut valve like a Mikuni, so your problem is most likely caused by running with the top off the air box, you should put the top on the air box , run 91 to 94 octane alcohol free gasoline and see if that is all that is necessary to eliminate the backfiring. If not you should go up one size on the pilot jet, possibly may need to raise the slide needle one notch and increase the idle speed. Final pilot screw setting will be determined after making the appropriate changes to the carburetor and intake and only after 15 to 20 minutes of riding - with the engine at normal operating temperature, connect an accurate tachometer, with the engine idling at the desired idle speed, turn the pilot screw "in" in 1/8 turn increments pausing 5 to 10 seconds between adjustments - when the engine RPM drops by 50 rpm, turn the pilot screw out one full turn and it's done.

I suggest setting the idle to 1600 rpm if you insist on running with air box lid off and want to get rid of the backfire on decel - other than being annoying, the backfire does not hurt anything. Changes to the intake and exhaust exacerbate backfiring from the exhaust and changes to the exhaust has the greatest effect.
 

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Discussion Starter · #4 ·
I got this bike with out lid. I think my main jet was 120 and pilot was 42 ? would this be a good set up for my bike ? the needle is not adjustable
I got this repair kit and mechanic replaced jets ... I'm not sure what jets came with this moose repair kit . I guess I would have to open carb to check.
but like I said "open air box uni-filter and stock pipe, what would be the recommended jets for my bike ? the reason I got the rebuilt kit was because previous mechanic tore down the carb including mid-level gaskets ( witch don't come in any repair kit --- u have to buy that separately ) like I said bike runs good ( just that backfire ) but i would like to know what would be the recommended jets for my set up thanks again
 

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Stock jetting was a 120 main (below 4000 feet above sea level - 115 above 4000 feet) and pilot jet was a 42 for all altitudes. The bypass starter jet is a 75 and above 4000 feet is a 72. The pilot air jet is a 100 for all altitudes.

With the top off the air box, the main jet might be bumped up to a 140 or 150, pilot jet will remain 42 and pilot screw backed out 1/2 turn - the OEM slide needle is adjustable. This is to tune the mid-range. It would be simpler and cheaper to get a lid for the air box out of a junk yard.

If you want to run with out a lid, stay out of water (only run on dry days) and get an assortment of jets to tune for changing atmospheric conditions.
 

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Discussion Starter · #6 ·
We run in baja mexico. its all desert, so I'm ok with out lid. would u recommend me getting a dyno jet kit ? or is that not necessary? !!! also I just ran into this problem :( my starter button is not working ? I put a screw driver to jump the solenoid to start the bike so I know the start is good .... would my problem be the solenoid ?
 

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Dyno Jet kit will provide an assortment of jets and it's up to you to select the right ones, so it's a start.

Starter? TRX450R is kick start - you must have a TRX450ER - only a little difference in the induction dept., but major difference in wiring.

The starter is controlled by the ECU - it has to see that the neutral light is on or the clutch lever has to be pulled in - check to see if the yel/grn wire at the solenoid has continuity to ground and the yel/red wire has 12v when the starter button is pushed.
 

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Discussion Starter · #8 ·
The green light never turns "on" the bike is in neutral and bike used to start but the light just doesn't turn on ..... bulb must me out.... is there a replacement bulb or do I need to buy one complete ? Besides the light... maybe its the solenoid that went out.
 

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The bulb is # 18 - part number 34908-KM1-671 - even with the bulb out it should work if the clutch is pulled in

Font Auto part Parallel Automotive exterior Drawing


Another possibility is if there is continuity on the ground wire and 12v on the control wire, is the starter diode
Rectangle Font Parallel Drawing Pattern

Part number 32146-S84-003
 

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No - the pilot screw is for idle only and is unaffected by changing the main jet - the pilot screw is only adjusted for fuel quality and high altitude - typically turn out 1/2 turn for alcohol blended fuel and in 1/2 turn for altitudes above 4000 feet ASL.
 
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