Jetting from scratch and hoping to eliminate some issues.

165 Views 5 Replies 2 Participants Last post by Walt427450R, 20 d ago

Walt427450R

Discussion Starter · 21 d ago

Alright, because I have this weird feeling I have never had the A/F mixture exactly how it should be since I got my 450R I thought maybe I could give everyone a list of mods and as much information as possible in the hopes a few of you will throw out suggestions on what my jets should be. With any luck a handful will be the same or close to the same and I will know where to start. So..........I have a 2009 trx450R, I have a complete FMF powercore 4 exhaust (header and tip), I have a uni filter and I do have my airbox lid on but it has 4- 1" holes drilled in it in addition to the original 1" hole/tube, so 5- 1" holes total. The elevation where I live is 5,000 feet. Where I generally ride is 6,500-7,500 but sometimes as low as 4,000. To my knowledge he didn't screw with the needle or anything like that. So, with that information could I get a few suggestions that would get me as close as possible. The mechanic at my local Honda shop was telling me about plugging something with epoxy inside the carb but I had no clue exactly what he was meaning, only that the end result would be alot more gas when I punch it.
Thanks in advance for any suggestions or advise.

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Bullvine rider!!

· #2 · 21 d ago

Your mechanic might be talking about the pin hole where your pilot screw is. Do you live in California? Because in cali they put a pin inside the pilot screw hole so you can’t mess with it (emissions). So people pull the pin and plug it with opoxy or silicone , opoxy would last longer. That’s the only thing I can think of as far as epoxy in your carburetor.
unless there’s some other mod I don’t know about.
As far as your jetting 🤷🏻‍♂️ im still trying to find my sweet spot, so im not sure what’s best for your quad. Although I speculate.
The two best things to do to get it close to perfection is a dyno with A/F meter, or weld a bung to your head pipe (its a female connection for a/f meter. Since I can’t find a dyno I’m thinking of doing the bung. Type in bung up top and check it out. And keep tuning bro you’ll get it where it should be. Good luck my man

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Walt427450R

Discussion Starter · #3 · 21 d ago

Bullvine rider!! said:
Your mechanic might be talking about the pin hole where your pilot screw is. Do you live in California? Because in cali they put a pin inside the pilot screw hole so you can’t mess with it (emissions). So people pull the pin and plug it with opoxy or silicone , opoxy would last longer. That’s the only thing I can think of as far as epoxy in your carburetor.
unless there’s some other mod I don’t know about.
As far as your jetting 🤷🏻‍♂️ im still trying to find my sweet spot, so im not sure what’s best for your quad. Although I speculate.
The two best things to do to get it close to perfection is a dyno with A/F meter, or weld a bung to your head pipe (its a female connection for a/f meter. Since I can’t find a dyno I’m thinking of doing the bung. Type in bung up top and check it out. And keep tuning bro you’ll get it where it should be. Good luck my man

Thanks man. Yeah I don't live in California. I thought it was kinda strange that the honda mechanic I have known for years and always been against rigging things, says "epoxy it" Haha. I figure if I start fresh with a clean carb and air filter and start with a 150 2.5 turns out, it should give me a idea. In my mind if it is a bi*$# to start and the idle is not steady or hangs too long before coming down, I'm lean. Also if I get going fast and let off the throttle and downshift, if it pops I'm lean. I just hope the 150 2.5 out gets me close.

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Bullvine rider!!

· #4 · 21 d ago

Walt427450R said:
Thanks man. Yeah I don't live in California. I thought it was kinda strange that the honda mechanic I have known for years and always been against rigging things, says "epoxy it" Haha. I figure if I start fresh with a clean carb and air filter and start with a 150 2.5 turns out, it should give me a idea. In my mind if it is a bi*$# to start and the idle is not steady or hangs too long before coming down, I'm lean. Also if I get going fast and let off the throttle and downshift, if it pops I'm lean. I just hope the 150 2.5 out gets me close.

I think it will. Its the pilot jet you need to keep an eye on. I have a 50 pilot cuz I had a little bit of hard start or hanging idle, went to a 50, what a difference. But your at a much higher elevation so 42-48 is where you’ll probably be. I believe 42 is stock. Let us know how you make out. Im always looking for jetting info. Good luck

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Walt427450R

Discussion Starter · #5 · 20 d ago

Bullvine rider!! said:
I think it will. Its the pilot jet you need to keep an eye on. I have a 50 pilot cuz I had a little bit of hard start or hanging idle, went to a 50, what a difference. But your at a much higher elevation so 42-48 is where you’ll probably be. I believe 42 is stock. Let us know how you make out. Im always looking for jetting info. Good luck

Great information, thank you. Does anyone know of a fast easy way to gain access to the jets ? I feel like I'm disassembling far more then I need to just to do this.

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Walt427450R

Discussion Starter · #6 · 20 d ago

Walt427450R said:
Great information, thank you. Does anyone know of a fast easy way to gain access to the jets ? I feel like I'm disassembling far more then I need to just to do this.

Higher elevation is less air so in theory I would need less fuel but because of the exsaust and air filter it should be bigger then 42 to start. Am I understanding that correctly

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