Jetting/Exhaust Issues

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Just put on a new slip on - HMF performance exhaust. For some reason came with a 160 main jet so we tried it for the hell of it bc my wheeler is running really lean which isnt good at all w/ the original stock jet. Wouldnt even start w/ the jet that came with the HMF. I called HMF and they said I should have a 152 and do something with 2 complete turns on some screw on the carb to make it run right? This sound right or . . . I just need some help plz

 

[yamarider]

They should have sent you a 152, if they're not going to send you one then you'll have to go to a dealer and buy one.

The screw they're talking about is the fuel screw, the small brass one underneath the carb. You should turn it in all the way, then back it out 2 complete turns

 

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Just put in my 152 main jet and did the turn on that bronze screw 2 complete turns and well she is not running right at all. She fired up fine and seemed ok but in high revs of each gear she wants to like die out on me almost it seems. Any suggestions? I thought I could handle this on my own but I guess not

 

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Also just read the how to on bluetraxx. How bad is it that I never had a spring in the carb when I took off that float cover? When I took off the carb there wasnt one in there so I thought that was odd bc it was in the how-to?

 

[yamarider]

My guess is that the 152 is too rich, but first i'd do a full throttle run through the gears, then kill the engine and check the color on the ceramic part. I suggest just using the plug that's in it now instead of a new one, it'll take the color better.

It'll run ok without that spring, it's just for the accelerator pump, but your throttle response will suck without it. If you didn't already, throw a spring in there, you'll notice an improvement.

 

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Yeh . . . I just cant understand why that main jet wont work properly. Should I just mess w/ that fuel/air bronze screw or . . . I am getting so pissed bc its so nice this weekend and here it sits in my garage. Just wish it would run properly already, so tired of this ****. What color indicates what again when I check the plug & also should i Have to change anything else in the carb w/ that new slip on HMF besides the main jet and bronze screw? Any suggestions are good at this point before I lose my mind . . . :

 

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Update: Just ran it and it was def. dark and like had sutt around the plug so im guessing that is rich. I am guessing that based on that instead of having a 152 from stock 145 I should put on a something in between for a main jet and try that right?

 

[yamaharaptor350]

yea try somethin lower than the 152, that is deff runnin way rich

 

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Sucks I cant ride today bc yamaha isnt open and I am stuck w/ it sitting in the garage. I also have a UNI air intake so that might also be why that 152 wont work properly . . . maybe I will try a 147.5

 

[yamarider]

when you get to the dealer get a 147.5 and a 150, the 147.5 should do the trick, but it's worth the couple bucks for the 150 in case you would need it, even later on for colder weather or when you do more mods.