I installed a Yz450f cam today on my 04, I have ???

I installed a YZ450F exhaust cam today. I also had the carb off to slightly clean. Anyways, it started after a little bit trying to get fuel in the carb. Once started I jetted up and down the block with no problems. Felt pretty nice. Nice 3rd and 4th gear wheelies. Anyways after I shut it down I restarted using electric start and it backfireed once. Then started. It seems to be able to repeat this. I have to give it pretty heavy throttle to start it. If I kick it, it starts on the first time, everytime. So my thoughts are I either missed everything by a tooth. (TOC was suspicious when I removed it anyways). Or the YZ must have a bigger Starter jet. I'm still stock on starter jet (book says 65, yamaha says 60). To anyone who has ever had their cams out, I'm assuming to be off, it would be way of at the timing mark??? Mine was closer to the small dash (to the right of)before the horizontal (I). Would it even run a tooth off? Suggestions? I'm taking it out tomorrow for testing.

My WR426 ran 2 teeth retarded on the exhaust. I'd previously checked the valve clearances, as this can be a problem. The midrange was strong, but it had idleing and starting problems. The top end was also down. Did you check TDC with a piston stop and degree wheel??


I have a YZ cam in my '04 WR. I haven't noticed any drastic change in the way it starts. It's a little finicky when electric starting but so was the WR cam. First thing in the morning requires a couple of twists of the throttle then no throttle the rest of the day. I did buy a YZ starter jet (72) but haven't put it in yet. When you installed it did you set it up with the marks the way they show in the manual or one tooth advanced like the old 400/426 mod? Since you're replacing the cam you need to install it as the manual shows. Just a thought.

72 starter, 50 pilot, 100 pilot air jet, JD red #5 needle and 165 main jet is where I would start. I had a yz450 cam in for a month last year before selling it and going back to a WR cam. It was too much for the woods for me. It would wheelie like crazy coming off of turns in third gear. :D Starting is the same as a WR once you jet right. Check your valve clearances as well. :)

I'm pretty sure I put the cams back in correctly. I'm going to check the valves and try the jets first. Indy, is the 50 pilot and 72 starter stock on the on the YZ?

Indy, or anyone have a copy of the JD instructions? I cannot find mine, they have YZ instractions also, correct?

If so can you fax or email to me? Thanks

See my signature for my jetting.

Runs awesome!

If your cam was out of time the auto decompression would not work. No kicky over!!

Thats why you had to buy a YZ cam !

I found the pilot had to be dropped from the 50 to a 42 for my bike.The main increased from 165(or was it a 162) to 170 or 172.

anyways go down on the pilot and up on the main.

The starter jet is only the choke.

I raised the needle 1 pos as well but I am running the optional yz needle (ndjn)

It would be a good idea to check the valve clearances though

My 2c anyways. :)

All Yamaha four strokes are tough starting with lean jetting. I believe the 50 pilot and 100 PAJ is stock on the YZ450's. I would shy away from a 40 pilot (that is for summer at 12,000 feet)? JD Blue #4 may be needed if you get lean backfire in cooler weather. Red #5 should be a summer setting. I never kept my JD instructions after I found them to be on the rich side for my bike. I have just kept track of my settings that work well for my bike. :)

Ok thanks. Just wanted to read the general settings. Anyways thought you guys would like this pic. The tank is a YZ450 with a seat that I made from WR base, YZ foam and cover. wryz.jpg

Hey, that looks super. I was thinking about going with a set of those Technoflex decals too, after getting pimped on the Enjoy set I ordered. They look super on that bike. Are those the SoCal Decal (www.decalmx.com) backgrounds, and did you order them specifically for the WR number plates - or are they adapted YZ decals?

The backgrounds are from Decal works. They are for the YZ. Seem to fit just fine. They do them very quick.

I'm confused! Couldn't you have just rotated the stock WR exhaust cam and gotten the same effect? Why spend the extra money on the YZ cam?

Cannot rotate 03 and 04. They require new cam.

Indy all the jet sizes check out with the YZ stuff. The 72 starter really helped. I could not find one in stock anywhere so I swiped out of my Yz250F. Anyways the stock pilot on a YZ450 is 42. Thats smaller then what came with my WR. 50 seems to be a large jump. Also I do have to hold the throttle open to start, with either kick or electric.

Just try the 50 pilot before you give up on it. The YZ guys seem to like the 50 pilot from their experience. 42 is EPA jetting. :)

I'm going to. Should I change Pilot Air jet also? What is stock WR? It's not in my manual. And one last stupid question. Do the Bigger size Air jets actually lean it out. Guy in the YZ forum said to get rid of high rpm popping on decel try a smaller Main Air jet. I'm going to leave alone until this weekend. Going to a colder place. Want to see if it runs better ot worse. It is already very strong, just trying to perfect.

Do the Bigger size Air jets actually lean it out. Guy in the YZ forum said to get rid of high rpm popping on decel try a smaller Main Air jet.

Yes, they control air, not fuel....that's why they call them "Air" jets :)

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