hey guys,

I spoke with the folks at Rath when I orderred the pipe, told them what i was running and they said that factory jetting should work fine. Since I don't know much about rejetting a carb, I yeilded to the experts and didn't rejet. Installation was a snap! The machine still started easily and seemed to make lots more torque so i was pleased.

The first performance test ran was a drag race against my friend's YFZ450. Since he has owned that thing, through my first three gears it has always been anyone's game, and depended entirely on who got the better launch. When I click to fourth, however, i always take off on him. That's just the way the race has always gone. We ran and it went exactly like that again. So I was kinda disapointed to be honest... but figured at least with more torque the power would be more usable.

The second performance test was where i realized the jetting was wrong. We ran times in a 75ish yard stretch (very rough estimation) and cbmboy was timing me. My first set of runs, i ran the pred almost to its rev limiter each shift (which has always been the fastest way to get through the gears on my pred) and averaged a 7.5s time. This was only .1s faster than his 400L so i was really surprised and decided to run a few more. The next few passes i short shifted (about 80% of the way through the rev range) and my times averaged just under 7seconds. Clearly the jetting was off and i was running out of gas in the upper R's. my dealer only had a 152.5 for my main so i bought that, but will be orderring a 155 tomorow. This seemed to give most all the rev out back, with the 152.5 I average just under 7 running almost to the limitter again, but i can't help but think a 155 would add a little more to my rev out.

Also, after changing the jets, this thing only takes until 3rd to run away from the YFZ now, which is a HUGE difference. The performance gain starts way low and i can honestly run a gear higher coming out of corners and the pipe just pulls me out without the big lag i had with the factory pipe. It really does a great job of broadening the powerband and even makes the predator sound more menacing. overall for only $235 this is a great addon to anyone's pred. And mine's not even quite jetted perfect yet... I think i need a 155 or maybe even a 157.5 main and a 50 for the pilot so i will continue to update this post with each jetting change and what they do, so that future customers for the rath pipe can see how to jet theirs.

P.S. sorry for the length... lol

 

Good to hear..and even better that the motor stayed together!

I had a Yoshi slip on and kept stock jetting..I tried a 155 main and it fell on its face in the upper R's..also had a K&N drop in.

 

yeah i'm kinda astounded that this thing has lasted this long... but i've got to say it's nice to finally have the machine i paid the almost 7k for!

P.S. Today i orderred a 47.5 pilot, and 155, 157.5 and 160 mains. Hopefully they're in by friday... i'll keep you folks informed...

 

I love The New RATH HEADER, It is awesome!! I have my pred bored to a 558,Falicon crank,dyna tech cdi,ported,1mm stainless valves,FCR carb,260i web cams,and both headers (new and old rath). The new one is Much better than the old rath head pipe.It looks great and the power differance is very noticeable. My pred is so fast on the dyna techs curve 3(nicholas Curves)That I can't even controll it in the woods. I had the same set up with the old rath header and it wasn't even close to being the way it is now.
the new rath header is the best head pipe you can get for the Predators.

 

Well looks like i have it figured out... tentatively of course, because i won't know until i put like 8hrs on it and do a spark plug test... but as of, 47.5 on the pilot and 155 main seems to work great! the extra pilot jet seems to eliminate the ocasional off-idle stumble i was experiencing and w/ the 155 main my times got all the way down to 6.67s average (6.62s best) over the same distance it was taking me 6.9s to cover w/ the 152.5 in. The spark plug check after 30mins of riding showed a very nice brown. Hopefully, a longer term test will show the same results!

Hope this information helps anyone looking for a similar set-up, and i'm just glad i can now start to help other people out w/ their jetting questions...thanks to everyone for the info that helped me to get this thing running great!