At this point, it sounds like you're just fine in the bottom and mid, but VERY lean at the top. If you go with bigger mains, all you're gonna do is drowned out the midrange. This is the EXACT same problem I had tuning mine. My 727 wants very little fuel in the lower and mid ranges, but A LOT on the top end. My suggestion is to go start my jetting specs(cut down needles as well). Which I explained earlier in this post.

 

I think it was kinda close at the begining after I moved the needle to the 3rd clip. I think i'm going to go back and, just go down a size at a time on the mains till it runs perfect.

I'm still a little unsure what the air mix screws do. I'm guessing they effect the hole rev range? but, How? i tried 2 turns out and, 3 turns out and, i have no idea what i was looking for? maybe i'll try 2 1/2 so i'm in the middle?

I don't know how you guys can stand this, I'll be gray haired or bald by the end of this tuning crap! LOL

 

also you might want to try changing the needle jets, that's what I call the long tube with all the holes in it that the needle sits in. I think you would be better off with bigger holes in it to allow more air and fuel to mix on the the top end where you are lean. On that does anybody know what size stock ones are.

 

it's called out as item 24 on the online micro fiche, but it gives no size and they call it a "holder". Is the one off a grizzly bigger??

 

Capt, here's the way it works:

The pilot jets and the air screws control off idle to 1/4 throttle.

The needle's taper controls 1/4 throttle to 3/4 throttle.

And the main jets control 3/4 to WOT.

If your header is glowing after a full throttle run, it means one of two thing's. Either your main jet is too lean or your exhaust is too restrictive. I'd guess the former is the answer.

 

Well, I'm Still Lost. It is still a little hesitant off idle and, under a 1/4 throttle but i ccan't tell if that is the Air Screws being lean or rich. It runs pretty smooth throught the revs after that but it doesn't seem like it is at it's best. Almost Doubling the HP of stock should be a big difference i think.

My Builder told me a trick to main jet testing. He said get it in 3rd and, rev it out when it hits top of revs lay off the throttle a little and, it should decellerate smoothly to the range you have the throttle at (Say 3/4). If you let off and, it still keep reving at same speed your rich and, if your revs cough and, dump your lean. Mine gave indications of rich. It tried this with 172.5/170 mains and, 170/167.5 now and, it seems a little better (not accellerating as much in the high revs when off the throttle) But i'm still not getting the arm yanking power i should have.

In my area and, at our dunes Sound is a big issue so i have to run a Quiet Core along with a spark arrestor. I believe this will plug up my restriction and, could cause the header glowing. But I ran it like this when just piped and, jetted and, it seemed to run flawlessly. In my builders defense they didn't jet or dyno w/ a quiet core so i'm really fudged!

Lastly, I tried running w/ my airbox lid on and, no snorkle (lost it) and, the bike would barely get over 1/4 throttle on 172.5/170 setting and, a little more with 170/167.5 jetting but, neither setting would get to 1/2 throttle. It started popping like a slow machine gun and, bogging. This tells me i'm still rich somewhere but, i don't know where. It was only 55* out too so, it will prolly richen more when it is warmer.

I'd say i need a dial a jet but, i'm not sure it works on built bikes and, i can't even seem to get a base line.

 

.

 

Have you tried running it with the jetting it came with, without the quiet core?

 

I am running 150 155 in mine at 6200'. The dunes we ride at I'm using 145 150's which is at 8200'. I kniow this sounds kind of lean but it seems to run best with these. i have tried severly combinations but one thing i can tell you for sure is stay away from the dynojets. i never could get them to work near as well as stock.

 

Well I'm done w/ this. I tried every combo of jets between 160 and, 175 and, the half sizes and, no go. It has about the power of a Raptor 50 but, doesn't run as well. I'm not sure if it is the restriction of the Quiet core or the needle setting but something is definitly FUBAR! (I lost control and, just put it back to the original way it was sent) If i take it apart for one more jetting change i'll have to replace the hole bike due to wearing out the parts from jetting changes. I'm 1 second away from Ghost Riding this POS in the Lake W/ Concrete in the tires!

My Builder told me he tested a BigGun pipe like mine on a stock rappy and, it made around 45hp. He said when he put in the quiet core it was about the same on top but the midrange fell out of it. Not sure if this could be it but? All I know is i rode it w/ the Pipe(w/ Quiet Core), jets and, Proflow before the build and, it was an animal compared to now. I don't care what pipe combo i have the the 686 build should be way faster than piped! THIS SUCKS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I shoulda listened to my instincts and, bought a Banshee or, just kept this hog piped and, been like everyone else. At least i'd be riding!