NEW WR450 Behaivor

I just got my 450 back from the dealer - they had to trouble shoot a kick starter issue. Anyway, before I sent it in I only got an hour or so on it. I rode it a little today and paid some attention to it and am just wondering if the following is typical for a new WR450 before any of the mods are done:

First off, the e-start almost never does the job when the engine is cold. I have to kick it to get it going. Once it warms up the e-start does fine.

When I am on the throttle I can hear faint popping or backfiring sounds. I need to be listening for them and usually don't hear them when I am riding.

Whenever I kill the bike it lets out one mediumish backfire.

The idle seems to float around and not stay at one RPM.

The mechanic at the dealer said the bike is jetted pretty lean (I've also read that on this forum several times about the 05 models). He said he would get everything dialed in when I bring it in for it's first maintainence since he would need to rejet it at that time anyway. I just want to make sure that my bike is behaving in a typical uncorked WR fasion before I get too much seat time on it.

Also, I've been trying to get it broken in before the warranty is up and the only place to do that right now is around our property (~5 acres). Basically I am riding a quarter mile loop that I made for mountain biking so it is pretty slow going in places. Occassionally I find myself in second when I should be in first and the bike bogs down a bit as I accelerate - mainly coming out of sharp corners. It's not a major hesitation but I can feel the bike struggling just a bit to get back up to speed. Is this something I want to avoid, especially during break-in? Or am I ok as long as it doesn't stall? I feel kind of dumb asking this question, I've just got new bike paranoia. I wish it was spring and I could take it out on a trail and just cruise for the break-in - maybe we'll get some unseasonably nice weather this month. Thanks for any help or advice with this.


I, also, recently bought a new 05 wr450, even after reading the forums. =)

I also orderd a YZ throttle stop, Zip-Ty fuel screw, and JD jet kit as well (all are on their way).

Your symptons sound just like mine, which TT and the bike mechanic at the dealer pinpointed: extremely lean jetting. I'm hoping that the JD jet kit takes care of that, because at 800ft ASL, my bike will not idle. So far my '81 XR500 rips compared to this bike, but I've been told that once the re-jetting is done, it'll be one mean machine.

But, nothing you said sounds different than my new experiences, and I've read nothing but praise for the JD jet kit. If you can afford a new wr450, you can shell out the $70 for the jet kit. =) At least thats how I looked at it.


All stock WR450's (sold in the US) run like pigs until you uncork the exhaust, rejet carb, disconnect gray wire, shorten throttle stop screw, etc. Use the search feature and you will find all the info you need and more. A few hours of wrenching and your new bike will run like the proverbial striped-ass ape!

I never ran mine before doing the throttle stop and gray wire but, with just those and no other mods it ran pretty good. I had to adjust idle speed for better starting. Since then I've done JD,zip-ty,exhaust snorkle mod, lowedog mod (along with other protective upgrades and suspension tuning) and it runs like a top.

My 05 WR450 has ran perfectly since the its initial ride on 12/25; I just pull the cold start knob and it starts fine (bonehead tip: make sure the fuel value is on; 1st day it was on Reserve and did not want to start until move to On).

This is my fist bike in 25+ years; thus my prior experience was Kawasaki KX250 motocrosser 2-strokes (very light and powerful). The WR450 was not a hot as I expected; its geared a bit high IMO, but once you get the rpm up -- not bad, even corked.

So, if you have yet to un-cork as recommended by "every" WR450 owner and can't stretch-it-out, it may feel strangled/muffled -- this I understand is normal until un-corked by doing the "free mods". However, the starting and backfiring issues you are having is not my experience.

I had my dealer do the mods the other day with the 1st scheduled service: exhaust baffle removed, grey wire disconnected, shorten the throttle-stop, air-box snorkel removed. I have yet to ride it, but the dealership's owner, tested my bike before I bought it, and the other day after the mods and said, " are picking-up twice the bike your brought in..."; I'll find-out tomorrow.

I'm at 500 ASL; not sure if I need to Re-Jet; was talking to the shop's mechanic, he said "no" -- anyone; advice?



I'm also at 500, running the JD blue needle in the #4 clip position, 170 main, stock pilot, zip-ty at 1.75 out, runs great. Temps are below 70 degrees right now. When it warms up I'll run the Red needle, same position. Hope this helps with your comparison. BTW your stock main is 165 and the nonadjustable stock needle appears to be in the #3 clip position.

Thanks for all the help. I will order the JD needle kit right away. Anything else I will need to order to do the essential mods? I'll search the forum to figure out how to do them but I want to make sure to order any parts that I am going to need along with the needle kit.


I'm also an old fart and this thumper behemoth is all new to me. How do I uncork the exhaust? Whats the grey wire? and where can I get a JD kit? I cut the throttle stop completely and put the screw back in, is this bad? some guys are saying they're using a YZ throttle stop. I'm soo confused.

Get the JD kit in the TT store, get a YZ throttle stop if you cut yours too short(the throttle slide can jam wide open with out a correct length bolt :cry: ). Look HERE for the gray wire and other free mods. Pull your seat and yank the snorkel out of the airbox then remove the six allen bolts from the exhaust and you can remove the exhaust tip(leave the spark arrestor)put the end cap back on with the six bolts. Sea level jetting should be about, 48PJ, 170main and blue JD needle on position 3 from the top. Also get a Zip-Ty fuel screw.(stock screw is impossible to adjust and covered with a plug stock)you can get the cover out by sticking a small pick in the hole and prying gently.


on edit: get the lowedog AIS block off kit or some rubber plugs and an 1/8 pipe plug and get rid of that AIS. The fitting on the exhaust manifold can be tapped for the 1/8 pipe plug although I also took the injection pipe and cut it off short and welded the end shut and then reinstalled it for a little extra protection against exhaust leaks. Doing this mod gets rid of the pop from the exhaust when you close the throttle.

Jasilva, Got any recommended sources for the Lowedog AIS block off kit?

I rode mine 100 feet before doing all the mods :cry: even removed the ais, JD red5, 170mj, zip-ty 1.75t, exhaust plug. Cold it starts faster with the kick starter. Cranking up the idle speed prior aids in faster starts. It's still easier to start than the 400-426's without the adc cam..:cry:

PM "Lowedog" and ask if he has any available.....

Jasilva, Got any recommended sources for the Lowedog AIS block off kit?

If Lowedog doesn't have any of his kits available you can do it yourself. Get an assortment of vacuum caps and a 1/8" pipe plug and a matching tap. Use the tap on the exhaust manifold where the pipe enters and then plug it with the plug and some high temp sealer/antiseize. Put the correct size vacuum caps on the airbox and cylinder head fittings.(use some RTV silicone in the caps to help seal and cement the caps on and use the stock clamps for a little extra insurance. I did mine this way and then just for extra insurance I took the AIS pipe and cut it right at the bell where it attaches to the exhaust manifold and then MIG welded it shut and ground it down smooth. Should take about 15 minutes to do the whole job.


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