WR450F and DR. D Pipes - HELP!!

Okay, I have searched EVERY thread for days it feels like and still have not found my answer for jetting without mods. So, I bought an '05 WR450 and a Dr. D complete exhaust system for it and have no clue what to set the baseline jetting at. The only mod I have made is the throttle stop screw and probably won't make any others. Dubach racing is telling me that the stock jetting is fine to run with the pipes, just adjust the pilot screw, but I know that can't be since it ran lean with the stock pipes. So I called Yamaha...three different dealers, three different opinions. :) I now have two places saying I HAVE to re-jet, and two saying I'm fine. I opened up the exhaust, my guess would be to re-jet. Can someone please recommend a baseline for me on my WR with only a pipe change? I will not be cutting the gray wire or removing the snorkel, just a high flow air filter. I will be running the bike in Northern California, sea level to about 4000 feet. The jetting database didn't really help since almost all are listed with full mods. Thanks for the input.

Out of curiosity, why aren't you pulling the grey wire or snorkel?

Jetting suggestion...48 Pilot, 168 main, '04 WR Needle @ #4, Adjustable fuel screw...SC

with the gray wire uncut and the snorkle still intack with the new pipe it is flowing better on the exhaust end but not on the intake.

This bike allready from the factory is very lean and runs very hot.

I would recogmend a basline of a 170 main 48 pilot slight adjustment on fuel screw.

Recogmend an adjustable needle either stock ys or shim the factory needle.

The JD jet kit works fine also, plus there is alot of data on this web.

Ride the bike and see how it feels at the different throttle settings.

Either boggy or sputtery and adjust as necessary.

Thumper faqs is a very good source of knowledge.

good luck.

trial and error will get the best setting.

I was planning on leaving the gray wire and snorkel intact for a few reasons. First, I'm used to track/sand riding on two stroke 250's and this is my first thumper so I wanted to get used to it for now. I wanted to get used to trail riding here in Northern Cal first since it is TOTALLY different from what I'm used to before I unleashed the beast! The bike's power is fine for me right now while I learn technical trail riding and am worried that cutting the gray wire will be too much for me to handle on the trail at first. There are also alot of water crossings so I am worried that if I remove the snorkel and anything should happen that I would suck water in easier. Plus the air filter gets pretty nasty as it is and I want to keep it as clean and flowing as possible. Am I off-base with my thoughts on this? Should I open it up and cut that wire with the pipes?

I'd open it up and learn to use it. Then you can use the experience of others for your baseline jetting. If you jet to a choked up intake, you're on your own and you'll just have to re-jet when you decide to open it up. Just my 2 cents :)

I would open it up and cut the grey wire. In order to suck water in through the snorkel you would have to submerge your bike. Check for the breather hose mod if you are worried about water. I have an 03 WR with a DR D pipe 170 main 48 piolt JD blue needle 3rd clip

Check for the breather hose mod if you are worried about water

The '05 already has the breather hose vented to the airbox. Cutting the grey wire doesn't produce a monstrous, uncontrollable hit. It only changes the ignition timing a bit, allowing the bike to efficiently use all of the extra gas the throttle stop mod creates. Furthermore, if that is your intended end result, then you're likely going to need a bit more carb tweaking once you do pull it...SC

Thanks guys, I'll let you know how it goes after this weekend. I took your advice and put in a 170 main, 48 pilot, washer under the needle clip, and a zip-ty fuel screw which I'll try at first at 1 3/4 turns out at first. Hopefully it works and I won't shoot flames from the pipe anymore from that lean mis-fire, or I kill everyone's weekend!

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now