Put on my new pipe and now my jetting is a wreck!

[memphis2857]

So I got my highly anticipated House of Horsepower exhaust in today and after several hours of bending, tweaking, and cussing I finally got it to fit. So I fired the ol girl up and instantly noticed how much different it sounds at just an idle. So I take off down the road easing along to let it warm up a little and already I could tell a big difference in how snappy it was for the first half throttle. Not jetting issues there. So I get it in 3rd gear lugging along and whack the throttle wide open and here is where everything went to complete shit! It went something like this: Baaaawahhhhhhh crackle pop studder crackle! LOL Anyway it breaks up real bad when on the main jet. I guess this is where I over (or under) thought the situation. I was thinking new pipe, no more corked up spooge cannon, I must need more fuel. So I went from 178 main to 180. No improvement. Back to the drawing board, I dropped to 175 and it seems better but, how can this be? Its still not right but it seems like I am going in the right direction. I am thinking I will drop to 172 and see what happens. What are you guys thoughts on this? Why is it messing with my head, and why do I need to lean out my bike with a new better breathing pipe?

Jetting Specs:
50/50 mix of Unleaded pump gas and 110 leaded fuel with Motul 800 @ 50:1
175m
42p
nedw #2
air Temp: 70 F
ALT: 750ft

Plug reading looks kind of weird because of the fuel mix i got going on.
Pulls super hard until it gets on the main in its current state.

[(F5)]

So why is it better breathing? But here's another slant on the thought process. Let's say that this pipe causes a stronger depression at some, or if yer real lucky most revs, there will be more suction pulling air in through the carb, ideally for longer. More air pulls in more fuel.

Don't over think it, just trial new vs old with jets that optimize that settup. Don't assume new parts always better than old despite money spent. Which is a bitter pill if it doesn't turn out, but often it does.

[memphis2857]

I assumed It's better breathing because it is a straight thru silencer vs. the q stealth that has all the weird baffles and junk in it. I dropped one step at a time all the way to a 170 main and it seems to be about where it needs to be. The bike pulls harder than it ever has now. Could be this new pipe is just that much more efficient?


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[(F5)]

Weird baffles and junk don't always cost power, although sound is a great deciever. Your engine spits out a mouthful then closes up shop for a while, there's often time enough to bleed off pressure, in fact having too large of a stinger diameter will lower the pipe temperature losing power. But there's more to it than that.

[Capz85]

I heard a good setting with that pipe was jd red needle #2,42, 172

[Wimpy525]

I have installed the hp exhaust on my bike as well. I am sorting through my jetting now. The pipe is that much more efficient, I found I was lean everywhere. I tried the JD red needle no good. I tried several other needles. I rode this weekend with a NEDJ, 42 pilot and a 180 main. Off throttle is good mid is good but may need to be a touch richer but the top was rich. I am going to try a 178 main this weekend and raise the needle.
Richard recommends a needle which I belive is a JD 2+2 #8 slide and 175 main. I am probably going to order this needle and see what it does. I have a #8 slide that just leaned everything out so I will try that when I get Richards needle.

[95jersey]

Originally Posted by memphis2857

So I got my highly anticipated House of Horsepower exhaust in today and after several hours of bending, tweaking, and cussing I finally got it to fit. So I fired the ol girl up and instantly noticed how much different it sounds at just an idle. So I take off down the road easing along to let it warm up a little and already I could tell a big difference in how snappy it was for the first half throttle. Not jetting issues there. So I get it in 3rd gear lugging along and whack the throttle wide open and here is where everything went to complete shit! It went something like this: Baaaawahhhhhhh crackle pop studder crackle! LOL Anyway it breaks up real bad when on the main jet. I guess this is where I over (or under) thought the situation. I was thinking new pipe, no more corked up spooge cannon, I must need more fuel. So I went from 178 main to 180. No improvement. Back to the drawing board, I dropped to 175 and it seems better but, how can this be? Its still not right but it seems like I am going in the right direction. I am thinking I will drop to 172 and see what happens. What are you guys thoughts on this? Why is it messing with my head, and why do I need to lean out my bike with a new better breathing pipe?

Jetting Specs:
50/50 mix of Unleaded pump gas and 110 leaded fuel with Motul 800 @ 50:1
175m
42p
nedw #2
air Temp: 70 F
ALT: 750ft

Plug reading looks kind of weird because of the fuel mix i got going on.
Pulls super hard until it gets on the main in its current state.

You didn't say what year or model? I have a 2014 XC300 with the HP silencer, but stock head pipe. My jetting went leaner as well. There is a major difference between the HP and stock FMF. The HP is definitely pulling more air and creates more power. I put in an NEDW on the 3rd clip and left the main and pilot alone. I tried the 2nd clip and it was too lean. After moving the needle up one clip it made a significant difference. Smooth linear power throughout the whole band and no hiccups or bobbles. Smooth starting and great idle. I am around 50 feet above sea level. This combo however does not like anything below 55F.

Just try moving the clip down 1 position, I think you will be pleasantly surprised. It worked for me, let us know.

[memphis2857]

Its a 2011 300. I talked to Richard and he seems to think the NEDW needle is part of the problem. I didn't think the needle affected WOT? I have a N3EW needle I guess I will try

The bike runs flawless all the way until you get into the overrev then it starts to breakup.

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[memphis2857]

Ok so here is where I am at
172main
42p
N3EW #2
AS 1.75
50/50 race gas/pump gas
Bike runs great on the road it starts to break up if held open (rev limiter?)
In a field and normal riding it's perfect

Attached is a photo of my plug



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[Wimpy525]

Sounds lean on the main to me. I would try a 178