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Discussion Starter · #1 ·
Ok...

I got my 450 absolutely screaming running through the gears. Here's the set-up. Gytr slip on, stock header(soon to be GYTR titanium), K&N filter with no lid, 175 main, with a 42 pilot(yep, not a typo) and 5th clip on the stock needle, and 2 and a half turns on the air screw. I went to a 48 pilot and regardless of what I did with the air screw it idled low and rough. I tried a 45, a little better idle, still rough. It runs the best with the 42 pilot, best throttle response, no popping on decel, and runs a lot smoother at idle. So first, how is it that guys are reccomending 48 and 50 pilots, when mine seems to run best with the 42. Second, why does this thing bog if I stab it hard right from Idle? It does it regardless of the jetting. It will just go PWLAWWW, POP! and sometimes it will die. Now, if I rev it to like 1500 RPM, then nail it, it revs beautifully, no problem, is this normal? If not, what's your best guess on how to fix it? I have never dealt with one of these carbs before. If I were to apply my automotive experience to this, I would rebuild the or adjust the accelerator pump, advance the timing, and check for vacuum leaks, but I am not sure whats going on with this. Any input is greatly appreciated.


Maxx
 

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First of all, why a 75 main? :what You said its not a typo...and what about the stock needle. From what ive heard/seen, u need to put in the GYTR racing needle, YZ stock needle (part #NCVQ), or the JD needle. If u did mean a 175 main, try changing it . Start at a 170, and then go up from there until u find the right jet. To tell u the truth, that 42 pilot does seem a bit small. The bike shouldnt even be ran without a 45 pilot :nono . Its jetted soooooo lean from the factory. I dont know how much uve messed with the jetting but u just need to keep at it. U cant just be changin one jet (pilot or Main) to see where the machine runs best. U gotta try all the combinations until ur machine is fine tuned. I know its a pain in the ass, but if u really want it running like a raped ape, u gotta do it. So change the needle, and start messing with the pilot and main. Is there even a 75 main? I dont know, but I say u throw in a 45 pilot but try a 170, 175, 178, and a 180 with that pilot. If u try all those and it still feels lean and pops a lot. Try the 48 pilot, and try all those jets on that. U have to find the right jetting in there somewhere, theres no way... Like i said, i know its all a big pain in the ass, but its just something u gotta do. Good luck man...
 

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Discussion Starter · #3 ·
DoH!!

Yeah, it's a 175. I bought it from a guy who had it about amonth and thought it was too much. he had the pipe put on, took the box lid off, and they jetted it to a 165 main, moved thee needle to the 5th clip, and LEFT the 42 pilot in. I was shocked because they had told my friend that they moved it to a 45. anyway, it is running great, it just seemed weird that it would when everyone is saying that you MUST have a 48 pilot, and with that in it was idling like crap. the main thing that concerned me is that deadness off idle with no load or no revs. Other than that she works fine. Thanks...

Maxx
 

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I run a 45 pilot at 2.5 turns out. It's usually best to be at 1.5 turns out on the fuel mixture screw so I (as you do aswell) should move up in pilot jets.....I'm just to cheap to get the 48 right now. ;) If its "popping" on decceleration you probably have an exhaust leak. So go through check all your connections, and even use some Hi-Temp silicone to seal the leaks. ;) Once that is done you can get a better reading on your jetting.

Also you don't just jab-and-stab the throttle on 4-strokes, they're more of a roll on power. But right off Idle has everything to do with your pilot jet.
 
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