ScramblerXE......you forgot to mention to him......and you list needs fixing........


#1......join predatorowners.com
#2....
#3......etc.....[img]i/expressions/face-icon-small-smile.gif[/img]

 

Thanks for explaining all that to me. Now I have an understanding of what is involved if I need to adjust them. It doesn't sound too bad. I am used to adjusting valves on full size cars and I'm pretty sure I can take care of it when needed. Question though, what are some signs that I need to adjust? I read about hard starting and sluggishness. Anything else to watch for? Also, how hard do you guys ride your predators? I do mostly trail riding with occasional wide open passes with maybe 5-6 wide open races per day when I ride. I really don't care for top end racing but I had to test it out yesterday against a modded banshee and a kfx 700. My main problem is keeping the front end down in 1st, 2nd and sometimes when I hit 3rd. They get a good jump on me out the hole because I have to feather it so much, but I run them down by 4th gear. This coming from me weighing about 150lbs more than them as well.

 

Answers: no it's not bad... and once you do it a couple times you're gonna be a pro. It is dependent on how much you use the upper R range (i.e. Race riding) which we always did. To give you a little insight, we've all got high performance machines, at the time that i had mine -> 3 Preds and Outlaw a YFZ450, 2 Z400s and a couple bikes. We raced all day everyday when we rode b/c all of us have tracks, so we just go to eachother's places... not to mention when the crops aren't in the fields we have literrally thousands of acres. Nothing promotes High RPM running like an entire 10 hr day of field running... perhaps that's what did my motor in so often... oh well, keep it off the limiter and you'll be fine.

Yes, when the valves need adjusted, you will start to run kinda crappy and it will be hard to start. However, i would check before this happens, or you could burn a valve. Checking valves w/ every other oil chane would be wise, to start, at least until you determine how fast your riding style will put them out of spec.

Also: i weigh 200 and had a full system, K&N and jetted, and sitting almost on the tank and feathering i could get a nice launch, (out launched my buddy's YFZ more often then not,) so maybe you're not leaning forward far enough? Stay up there until you click into third, and you should be ok, also: the bane of my existance was shifting from first to early. When the frond would come up, i'd instinctively shift when i first got it, and it would bog... hold on to those gears till about 8500 RPM - 8800RPM, that's about the optimimum shift point stock (in my experience... and mine came w/ the pipe cause it was an LE, so that might be different...) of course, that peak point can be moved wherever you like with tuning... good luck, you definately found the right crowd to help you out [img]i/expressions/face-icon-small-smile.gif[/img]

 

ScramblerXLE-

I installed the JD Jetting kit in my Yamaha WR426 (Motorcycle). It was THE best mod I did to it. If you?re not familiar with that bike they are a high performance off road bike that come Very plugged up from the factory. After doing all the "Free" mods to it, JD kit was the most noticeable.

As far as valve adjustment goes my bike is the only four stroke I have. I checked them often, they never needed to be adjusted. They will need some this spring because they where getting close last fall. I red line it often, 11,500 rpm. I also change my oil about every 200 miles. I don't go by hours.

 

I'm actually a fan of that motor [img]i/expressions/face-icon-small-happy.gif[/img] i think the YFZ 450 is a derivative isn't it? that is to say, the 426 was the same DOHC 5 valve type of motor?

Yamaha's YFZ has 2 things going for it regarding valve adjustments not needing done often:
1) Titanium Valves: obviously these will hold up better
2) Valve lash: The YFZ motor's cam lobes are literally like half the size of the Pred's. however, due to the smaller engine size and smaller carbeurator, it doesn't need to flow as much, and with the 3 intake valves it flows more than enough for it's slightly smaller engine. (hehe, on a side note, when we're all doing motor work in the garage on a saturday, some of us Polaris guys will pick up the YFZ guy in our group's cams and call him "Mr. Girly Cams") lol!

Anyway, i think that's why the Yamaha valve train doesn't need adjusted as much... wish the Preddy had Titanium valves, but i guess this is just something w have to live with.

P.S. Thanks for the info regarding the JD jet kit [img]i/expressions/face-icon-small-smile.gif[/img] i'm really hoping it wakes up my 525 even more (when it finally gets here.) i didn't want to break it in lean, so it will be installed immediately

 

Ok. Ya'll definitely ride harder than I do on my pred....lol.. I don't have any tracks close by and we only race maybe 5-6 times in a full day of riding. I don't really like top end and I'm really working on trying to launch it without flipping over. The truth is I weigh a little bit over 350lbs and even with me on the gas tank it still stands up all of 1st, 2nd and the beginning of 3rd with me shifting right before it hits the rev limiter. It is a completely stock pred as well so I can only imagine how fast a modded one would be. I simply can't stay on the throttle until 3rd and that's why they can jump me at first, but I still reel them in by 4th gear and start to pass. I'm very happy with it so far. On a different note, I ran against my buddy with the 06 kfx 700 last night from a standstill to 50mph with my scrambler 500 after I put the pipe and k&n on it and he put 6 bike lengths on me. Shoot I'm impressed with the scrambler for now. I know that the clutch will really wake up my scrambler and can't wait to get it installed. I'm the only one with a speedometer in the group and it's on my scrambler so that's the only way I could race to 50 without having to guess. I'm loading some pictures to my photobucket album now and I will post the link shortly. Should I leave the pred stock and if not what should be my first mods other than a K&N? Thanks again for all the help and suggestions.

 

The best pipe combo is the Pure Polaris muffler (which is a Whitebros. Part,) and the Rath Racing Header. This will produce a LOT more power over stock [img]i/expressions/face-icon-small-smile.gif[/img] i'm sure you'll be happy! i sure was. I think about a 155 on the main at that point, and if i remember right...maybe a 47.5 Pilot? i think that's how mine was set up... produced a nice over rev with a very smooth transition reigion...

Here are the posts i posted a while ago: hope it helps

Post #1)

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

post #2) (the more important post)

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

Hope all that helps [img]i/expressions/face-icon-small-happy.gif[/img]

 

Thanks for posting that. Where can I find the header and pipe at?

 

Yes, very similar. They upped the CC's to 450 in 2003. The 5 valve motor is by far the most reliable motor I have had. I am not sure why but YFZ motor is not a powerful as the ones in the Motorcycles. I think the YFZ motor has slightly less compression. My 426 is 12.5:1

 

Scrambler you will want to rejet your 525 right away like you said. It comes with a 148 main jet. Of course it was in the single and teens when I got mine so it was extremely lean and the plug was ghost white. I went with the JD jet kit and he e-mailed me the following set-up.
Red needle # 5 clip from top, 1 3/4 turns on air screw, 170 main jet with open air box or 162 with closed air box.

This made a big difference in power. He also gives you an o-ring that you put on your accelerator pump. There are 2 sizes the smaller o-ring results in a 40% increase in fuel spray and the second o-ring results in an 80% increase in fuel spray. The o-ring does not allow the accelerator pump to lag behind the throttle. This simple o-ring mod makes for absolutely no delay after punching the throttle.

Earlier you said you had a copy of the service manual for valve adjustments on the Outlaw 525. Any way of getting a copy of that from you. It would be very much appreciated. PM me.