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Discussion Starter #1
I just mounted a complete HMF exhaust system to my TRX450R. I changed my main jet from 118 (stock) to a 168 jet size. With the lid on, I noticed when accelerating it tends to bogg down, but it seemd to idle ok, at half throttle to full it loses power. Is this a lean condition, I tried to choke the carb to richen the condition, and it did'nt seem to make a difference. I noticed that other aftermarket exhaust systems require a 180 main to start with, what should I do from here?

I will be mounting a Dial-A-Jet to my carburator, hopefully this will allow me to opperate the adjustments externally with a nominal main jet setting. TPI (dial-a-jet) reccomends to set the main jet leaner by 1-2 sizes from the reccomended main jet size due to the emulsification that occurs by using the Dial-A-Jet.

Any reccomendations would help from here.

The HMF Exhaust System looks really nice and has an impressive sound. The installation was a breeze, all the mounts lined up perfectly. The guys at HMF did great job with the system.

Thanks,
Tim
 

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take your lid off and see what that does.

do you want to cut a hole in your airbox? I ride mainly mx so i really dont need it.
what do you ride? mx, trails, etc....

I also have a full HMF exhaust. I put the 180 main in and left the needle alone. I did cut a hole in the airbox lid though. you can see pics in the exhaust installtion topic. I actually think i am a little lean. I am going to be going with a 185 main and i will be messing with the needle.

i think you are a little rich with the lid on, and no breather holes.

schmitthead
 

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Discussion Starter #3
Thanks Schmitthead, I mainly race Mx 95% of the time. I bought an extra airbox lid to modify and duplicate the lid used in the HRC kit.

How did your 450R respond using the 180 main jet, and was the needle in the stock position?

Keep me posted on your carb settings, I will try a 180 main using the Dial-A-Jet.

HMF did not recommend to change the needle position, if you find that changing the needle position allows for better throttle response, let me know.

Where do you race? My friends, brother, wife and I race District 11, and some outlaw tracks in the area. We are racing up in Detroit at the Silverdome April 4th, the Pros race on the 3rd, and the Beg-Nov-Adv classes race Sunday (4th). You can register online @ http://michmda.org/page.cfm/9/ - Silverdome Supercross

Thanks again, and good luck to you this season.
Tim
 

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Discussion Starter #4
Schmitthead,

How did you wire your Kill Switch, I just want to be cautious wiring it correctly so that I don't disable the fan and other electronic devices? I read that you can splice (1) wire from the kill switch to the black/white (ignition) wire from the key switch, and the (2nd) wire from the kill switch to the green (ground) wire from the key switch, or ground the (2nd) wire to the frame?

Thanks,
Tim
 

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The 450 responded real nice to the exhaust and jetting. I do believe i am a little lean still though.
I actually do not race yet. Me and dave (m3zy6) are trying to get ready for the next season.
as for the kill switch, i found this on another site

connect the black/white wire to one wire on the kill switch and the green wire to the other wire on the kill switch. Then connect the other two wires in the key switch connector to each other and you are done. If you don't connect the other two wires the fan wont work and the carb heater won't work along with any lights.[/b]
i hope this helps, like i said i havent done this but i have seen this a couple of times.
 

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With the airbox modded like the HRC kit, HRC endcap, and a new air filter, I run a 185 main jet. It runs great!! does not feel rich at all. When you open up that airbox, the jetting really changes alot! Sparks suggest 190 with their exhaust and 185 with the hrc endcap/stock exhaust
 

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I have the Sparks full exhaust with sparks filter system, i run a 190 main and 2 turn out on the air/fuel screw seems to be a lil lean i may hop down to a 185 and just for kicks maybe up to a 195...if that doesnt help ill move the clip on the needle up one slot
 

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Originally posted by Nasty450r@Mar 15 2004, 08:34 PM
I have the Sparks full exhaust with sparks filter system, i run a 190 main and 2 turn out on the air/fuel screw seems to be a lil lean i may hop down to a 185 and just for kicks maybe up to a 195...if that doesnt help ill move the clip on the needle up one slot
?......If it is running lean with a 190, why would you go down to a 185?
According to Sparks you should be running a 190 with the needle on the 3rd position. Ive been hearing that even that is a little lean...is that the way yours is now? I think what I would do if I were you is just go up to a 195 and you should be set....I may be wrong though...just my thoughts.
 

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ok i will try what u said 1st and see what happens ill let u know prolly later on this week, ill have to make a trip up to the honda shop for some mains. appreciate it!
 

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Originally posted by Schmitthead@Mar 12 2004, 04:31 PM
take your lid off and see what that does.

do you want to cut a hole in your airbox? I ride mainly mx so i really dont need it.
what do you ride? mx, trails, etc....

I also have a full HMF exhaust. I put the 180 main in and left the needle alone. I did cut a hole in the airbox lid though. you can see pics in the exhaust installtion topic. I actually think i am a little lean. I am going to be going with a 185 main and i will be messing with the needle.

i think you are a little rich with the lid on, and no breather holes.

schmitthead
dude you need to turn the hex nut twice for the main and pilot jet try that thats how it will work.
 

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i have the hrc kit and a k&n and am planning on putting on an hmf exhaust,does anyone know if i could just put on the pipe and leave the carb and airbox alone.thanks
 

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Straight from the HMF jetting specs. "All pipes with jetting require setting the air fuel mixture screw 2.5 turns out from the dead bottom. This will eliminate off throttle popping. If popping persists back off to as much as 3.5 turns out." As for the correct jets: "450R 125/135 jets with the air box lid on. 180 with the lid off." I have mine on order and I will run a 125/135 with the lid on.
 

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I cut the airbox lid like the HRC and am running a 180 main with a pipe...runs great, didn't need to change the needle, but i am changing the pilot jet.
 

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Discussion Starter #15
sethg,

Did you have any problems starting your quad with the set-up you described. I would like to know why your changing your pilot jet. I have the same set-up - HMF full System - .180 main - needle in stock pos. - open airbox lid - Dial - a - Jet.

I seem to have some problems starting the quad after it sits for a few days. Once it is warm, it starts ok. I plan on richening my needle by one position, and maybe going up one size on my pilot jet.

I was just curious why you are changing your pilot.

Thanks
Tim
 

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I'm changing my pilot because of the lack of fuel at the very bottom. I'm killing it too often.

It sounds like your running a little lean...I'm not running an open airbox, only the HRC cut out. I'm also only running a slip-on exhaust, not the full system. I would go up a couple more maybe a 185 or 190 on the main and see what happens.

If your running in cold weather, that could affect it too, I've heard of that.
 

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I know the majority of you run open air box lids but I installed my whole system this evening. I used a 135 jet with a closed airbox lid and turned the fuel/air mixture screw out 2.5 turns from bottom and the quad seems to run great!!! Have not really ridden it yet but should this Saturday. Has anyone set thiers up this way??? Just curious to see how the performace was if so.
 

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Discussion Starter #18
Motoman,

IMO, I think you will be running to lean on your air + fuel mixture. Make sure you do a plug check at mid range and top end.

Good luck,
Tim
 

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I cut the airbox lid like the HRC and am running a 180 main with a pipe...runs great, didn't need to change the needle, but i am changing the pilot jet.[/b]
I'm changing my pilot because of the lack of fuel at the very bottom. I'm killing it too often.[/b]
Before changing out your pilot jet, I would try a 185 main, and then a 190 main to see if helps out from cutting out. I know that as soon as you open up that airbox, the bike needs a big main jet up, even if you are using just the HRC cut airbox lid. I'm just running a sparks filter, the same type airbox lid like you have and an HRC exhaust end cap and I run a 185. Most people I have spoken to have not needed to change thier pilots out. What needle clip are you on? I'm on the 3rd clip from the top, needle position would be more of a reason for killing it on the bottom then your pilot jet. Try dropping the needle clip one position (if its in the 3rd clip from the top, then put it in the 4th clip position from the top), this will richen it up. Your pilot mostly affects starting and idling. I just seems like too much of pain to get to the pilot, so I would avoid it if I could.
Joe
 

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Originally posted by timscherer@Apr 7 2004, 09:25 PM
Motoman,

IMO, I think you will be running to lean on your air + fuel mixture.  Make sure you do a plug check at mid range and top end.

Good luck,
Tim
Are you thinking I may need to turn the screw back in 1 turn??? They come stock with the air/fuel mixture screw out 1.5 turns. If I went back 1 turn it would then be back to stock. I guess the best way is to just check the plug.
 
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