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Discussion Starter #1
My sons friend challenged him to a best of 5 race up comp hill at Dumont Dunes.
My son on his jetted/piped/paddled YFZ 450, his friend on a very built Honda 400ex.

They've been talking this race up for over a month.

I forgot to put the card back in the camera, so you'll just have to live with my story.

I jetted my sons YFZ450 with 45P/165M/3rd clip yz needle/2 turns as per instructions on daddogs dirt riders page (lid off for the race).

The Challengers 400ex was a fast quad, but he got beat by my son on his YFZ 450 by over 10 quad lengths- 5 times.

Then the challengers dad raced us with a LA 450 sleve/jetted piped Banshee and the dad got beat by about 3 lengths each race.

All friendly, all in fun.

I re jetted both mine and my sons YFZ's after several in this forum stated that how they run in your driveway vs how they run on the dunes are 2 different stories.

If ya have to be the fastest, then I suggest going to bigger jets; 48 pilot 168/170 or bigger mains, apropriate clip setting and airmix.

But if ya want a jet and forget, no hesitation on hole shot, I-don't-have-to-be-the-fastest, but still incredably fast YFZ 450 owner, then the 45/165/yz needle/Yoshi pipe is the formula I suggest.

We were at Dumont Dunes for the past 7 days and our YFZ 450's started up on 37 deg F mornings with no choke, no problem, first touch on the starter button.

The Yoshi pipe performed best with the med sound silencer installed. 96 decibles.


The winner
 

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Good point on the driveway vs. dunes issue with the jetting. I'm hoping to get mine dialed in to a "happy medium" for the dunes as well and the 45/165/3rd or 4th on the YZ Needle/2 turns on the screw setting sounds like a good place to start.

Then tweak to taste.

BTW... what gearing were you running in the races? From the posts I've read I'm planning on going with a 15t front and stock rear sprocky setup and was curious what you were running.

~S
 

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Discussion Starter #3
Originally posted by YFZFoFiddy@Jan 1 2004, 02:29 PM
Good point on the driveway vs. dunes issue with the jetting. I'm hoping to get mine dialed in to a "happy medium" for the dunes as well and the 45/165/3rd or 4th on the YZ Needle/2 turns on the screw setting sounds like a good place to start.

Then tweak to taste.

BTW... what gearing were you running in the races? From the posts I've read I'm planning on going with a 15t front and stock rear sprocky setup and was curious what you were running.

~S
I suggest 3rd clip, but get back to us if ya have good results with the 4th.

You will be astounded with the difference in power,, absolutely astounded.

Good luck!!
 

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I'll definitely try the 3rd clip first.

Not sure when our first trip to the dunes will be... but it will be sometime in the next couple of weekends for sure.

Just waiting on the UPS dude to deliver the rest of my stuff! :woo
 

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Discussion Starter #5
Dropping the tooth count makes a huge difference from what we've witnessed, but then, of course rideing skills kick in because it's a wheelie machine.

We're still stock on the tooth count.
 

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Hey yzf450 kid,
I'm running a Yoshi pipe as well (full system) and may have my jetting a bit fat at 180 main, 48 pilot, GYTR needle on 5th and 2 turns on screw. I notice you are going much smaller on your jets, DO you have a K&N filter on your YFZ? I wonder if I should drop my jettings a bit? The bike runs good although at times I have a hard time starting it and I believe my bottom end is a little weak, once it hits mid and top end the thing is a beast.
 

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Discussion Starter #7
When I pulled out the silencer the YFZ lost it's low end, then I put it back in and BAM!, the snap came back.

It's only a slightly smaller tube with screen, nothing else. Fits inside unnoticable.

Stock airfilter, carefully cleaned and reinstalled.

I use the 1" dia unifilter plugs in the lid of the airbox. Keeps sand out, same performance gain as lid off but cleaner. Six Bucks from RockymountainATV.com.
You can hear the increased airflow with the lid off, and just feel it in power.

The fatter jetted YFZ450's were faster up the hill, but they also had lower front sprocket counts, the cam mod, and I believe I smelled AV gas.

They creamed everyone in hillclimb races.
 

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Hello guys,

My buddy bought his yfz about a month ago. I bought mine a week later. Within 2 more weeks , 4 more friends joined in the craze!

Well now it seems everyone has ordered their pipes,filters and jet kits (3-HMF,1-Yosh,1GYT-R).

I'm going to try to do the work myself rather than take it to a shop. Any tips? I'm at sea level,will that affect jetting at all? We found that we are always at the rev. limiter, so some of us went up a tooth or two. Will that affect jetting?

I also wanted to try the cam mod. Am I getting in too deep? How complicated is jetting and the cam mod? Is it as easy as jetting a holley and deg. a cam?
 

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YFZmaster:

You can do it all yourself with simple tools.

Look on the front page under "reviews" for the cammod information, http://www.yfzcentral.com/cammod.htm ,
and in the performance section under jetting (pinned to top of the section) http://www.yfzcentral.com/invision/index.p...ct=ST&f=8&t=908

If you read through all the instructions THEN ask specific questions about things not covered in there, you will get all the help you need.

Also look here http://www.eskimo.com/~daddog/



As I have stated before (and got ragged on) If you read those instructions and you are still confused, you may want to take your bike to the shop for the cammod.
 

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Discussion Starter #10
I thought I had made a mistake when my sons YFZ sputtered a bit.

It turned out he was holding third gear too long and was sitting on the rev limiter.

Ya can barely feel it or hear it when your riding,, but down below watching I could.

Several Yamaha mechanics, and 2 yamaha dealer/owners walked up to him and determioned that, and told him he was sitting on the rev limiter, and it was what was making the popping sound, and he needed to shift at or slightly before that point.
 
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