New Guy Checking In, 2003 450

2 replies to this topic
  • over rev

Posted April 11, 2012 - 01:10 AM


Howdy, I just bought my first thumper since my xr250 back in the 90's. I have ridden cr500's for the last 15 or so years. I'm so excited to have this bike, Ive always been interested in the " new" thumpers. Seeing as how out of shape i'm in, and my lack of current dirt riding experiance, Ive been reluctant to ride my cr the last 5+ years. The cr is alot of bike and I guess i'm just losing interest with it. Not that the 450 is a slouch, I'm just hoping it's a little more user friendly.

I do have several issues, and i don't expect them all to be answered in this thread, my main goal was to introduce myself.

But since I mentioned issues, lol.

The main reason I was able to buy this bike was I got it for less than market average due to it won't hold fourth gear. It's not a huge concern ( as long as it doesn't grenade) because I don't plan to do much high speed riding ( lol ). I have only riddin the bike three times and do find myself attempting to shift into fourth, it's very hard to remember not to!

the previous owner stated he bought the bike this way and rode it for several years, so I'm hoping to be able to do the same. He stated he never saw any metal, or debris in the oil.

Another issue is it's lean. It's hard to start, and requires the choke to run. I cleaned the pilot ( it was blocked) and it's a little better but still needs the choke. I believe it needs a bigger pilot, of coarse I forgot to look at the size while i had it apart. I should have known better as the fuel screw was out 4.5 turns. Also, There was NO freeplay on the hot start lever, so I adjusted that and will wait till next time to see if it helps.

lastly, it's loud as sin. it has a fmf pipe and i'm curious if it can be disassembled and packed. more so, I'm wondering if that is a worthwhile thing to do as far as cost, and how long it will stay " quiet".

I was able to find a manual, and read lots of good information on here already, and wanted to thank you all for contributing to the forum.

over rev

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • grayracer513

Posted April 11, 2012 - 07:32 AM


4th gear will require the replacement of the 3rd and 4th pinions (on the main shaft) and the #2 shift fork at minimum.

The hot start cable may have been the root of your carb troubles. With the choke on at idle, working the hot start should noticeably change the sound and speed of the engine almost as if it were a thumb throttle.

Bear in mind that the passages leading from the pilot jet and screw to the air stream may also be obstructed.

The pipe can be disassembled and repacked. This usually involves removing rivets from the can at the front joint. Be sure to use a good 4-stroke rated packing, in pillow form if you can find it.

  • over rev

Posted April 13, 2012 - 06:08 PM


yes, I need to redo the carburetor, and take some more time to ensure the passage is open. It's a little better with the pilot unpluged, and the hot start adjusted but seeing as the PO had the fuel screw out 4.5 turns, I'm guessing i need a bigger jet. It's not warm here in mn either, like 55-60*. I took it for a rip, and it still needed the choke all the time, I'll get it eventually.

the trans is a bummer. it has a 44t rear sprocket, and a pretty big front as it's rubbing the heck out of my case saver. It makes for a tall first gear. But I think I need to leave it as i need the speed.

my o-ring on my hot-start plunger is good but the plastic nut that holds it in is stripped. I'm wondering if that is under vacuum? I'm wondering if having that nut stripped is causing a lean condition?

also, my choke wont stay out, is there a trick to get it to click out, and stay?

Edited by over rev, April 13, 2012 - 06:10 PM.

Related Content


2016 YZ450 by CaptainKnobby

Dirt Bike   Dirt Bike Technical Forums   Suspension
  • Hot  59 replies

First Hare scramble tips by dhend8

Dirt Bike   General Dirt Bike Forums   General Dirt Bike Discussion
  • Hot  33 replies

Help with 2000 yz426 by weekend woods racer

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • Hot  36 replies

Is the 2016 GYTR Yamaha YZ450F too fast? by Fryboy

Dirt Bike   Special Interest Forums   Pro Racing
  • * - - - -
  • Hot  241 replies
WR Camshaft Swap Info - last post by jamesm113

WR Camshaft Swap Info

  • 0 replies

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.