Fuel Screw Fell Out!

After installing the Ti4 slipon on my '04 WR450 (beware, you have to use the quiet core insert, or at least the 1.5" cap insert to keep surrounding property owners and other riders from shooting at you), I had to open the fuel screw by a half-turn to get the idle and off-idle mixing right.

No problems, bike ran great for several hours on three seperate weekends, but suddenly, yesterday, she started popping severely on decelleration and stalling, even some nasty backfires. I thought, &%$#@!? Clogged jet?

When I got back to base, I found the stock fuel screw had fallen out of the carb and was just barely sticking up into the hole and resting on the starter motor. Dang, I'm glad it was still there, or my riding would have been done for the day.

When I reinstalled it, I found the tension spring wasn't even contacting the screw at two turns out, at least I couldn't tell if it was. So, I pulled it out and stretched the spring out and twisted the screw about 2 turns IN from unthreaded (tuning by ear), because I didn't want to smash down the spring again. Good 'squeak-age' from the tension spring this time, so it should stay put until I get the Zip Ty screw from the dealer.

The Ti4 pipe looks great (blue-purple annodized), wwaaaaaayyyyy to loud in stock form, but does seem to improve performance slightly over the uncorked stock pipe and saves several pounds from stock. If I need it quieter, I use the quiet core insert, but for most riding, I use the 1.5" cap insert, solid bark, but not too loud for my private property riding areas.


kind of suprised you didn't get a "Q". you do miss the 500 don't you. hope you'll have the quiet insert in for the two day. better check to see if you have all the parts( o-ring and washer) on the fuel screw. it's not uncommon for them to fall out when they're backed out three or four turns. not so common when they're only out one to two. the shops got more. you really have to get hold of me so we can go riding this winter.

All that came out was the screw, spring and an o-ring. Seems to be all good, now.

Hey, I've been riding every weekend at my place, except the one coming up (I'll be on the FJR in Texas). Let's go riding anytime! I do most of my riding at my ranch, 'cause I can do family time and riding time, at the same time. Just gimme a whistle and we'll go. Everybody at Donelson knows my phone number.


There should be a washer between the o-ring and spring....

once had to use a stick for a fuel screw when it fell out of my yz490. made for an interesting trip back to the trailer

Thanks for the heads up on that RichBaker.

I guess I'll have to get a new washer, then.

I just checked with the dealer, you have to buy the screw, washer, o-ring and spring as a set from Yamaha. Does anybody know if the Zip-Ty fuel screw comes with new pieces?


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