03 Yz450 tear down!!

[Chriswells85]

Some of you may have saw the little pic of the Used Yz450f i have purchased... im getting ready to strip it down and clean it up... It almost scares me to see what need replaced.... (the Girlfriend dont like the idea of spending the money haha) Ill take some pics and post them for a before and after...

Ive let it sit for about a month and a half and im having one heck of a time starting it.. I just replaced the spark plug... The one that was in there was pretty black, but i still cant get it started, and the tip of the plug is wet with black one it every time... It just stays flooded (im not using choke or pumping the throttle at all) ive let it air out abit and gave a few kicks without the plug to blow it out, but didnt work.. any ideas? oh and it is getting a good solid spark.

[MuDPoUNdeR]

Step #1 - Clean the carb.

[Chriswells85]

Thanks MuDPoUNdeR, i was just reading that in another thread? Guess i should use the search function a little better.

[grayracer513]

(the Girlfriend dont like the idea of spending the money haha)

(im not using choke or pumping the throttle at all)

It's not her money yet. Bear her current attitude in mind when planning your future.

If you don't use the choke and/or prime the engine with the throttle, how do you propose to start this thing during a Kentucky winter, just exactly?

Assuming the carb is in the proper condition (did it run when you bought it?), the correct cold start procedure, even in the warmer months, would be 2-3 twists of throttle to prime, pull the choke, push through to the first compression stroke, and give it a full kick with the throttle either fully closed, or cracked open just barely off idle. Cold starting requires extra fuel, and colder weather increase that need.

[mc1hd]

Sound's like the float's are stuck. Clean the carb and blow out the jets, check float height.

[Chriswells85]

If you don't use the choke and/or prime the engine with the throttle, how do you propose to start this thing during a Kentucky winter, just exactly?

Its been really warm this week, If tried both, with and without, i just posted i wasnt using the choke and so on because i read on a post someone saying that not part of the "ritual". And the last time i messed with it i wasnt using it. Ive now read over it and saw where you corrected them... Thanks for all the responces guys, ill let ya know when i get her fired up.

[MuDPoUNdeR]

2-3 twists of throttle to prime ... Cold starting requires extra fuel, and colder weather increase that need.

With my bike stock this never worked for me ... It always flooded the engine. When I did the BK mod this trick worked for me. My fuel spray was pretty long though stock?

[Chriswells85]

I did a search and found nothing, is the 03 yz450f compatible with BK mod?

http://motoman393.thumpertalk.com/tech/carb.html

that doesnt list it but it doesnt list anything over 2002?

[grayracer513]

I did a search and found nothing, is the 03 yz450f compatible with BK mod?

No. The BK mod only applies to YZ426 models. The '03 and later YZ450's had the accelerator pumps set up differently when they left the factory.

[Chriswells85]

Thanks again Grayracer?

[travisn]

lets see this tear down, I just got a 99 yzf400 and kinda want to do some tearing down and cleaning.

[Chriswells85]

Another question... I just got the bile to my uncles garage tonight.. He thought the problem might be the accelerator pump causing the above problem.. Is this likely?

[FinchFan194]

It's not her money yet. Bear her current attitude in mind when planning your future.

LMAO that is some good advice! ?

[grayracer513]

.. Is this likely?

...No

[Chriswells85]

Ok, took the carb apart, and there was some green colored grime in some places.. And the little piece that the Floats lift up was stuck from the grime. Cleaned it up, and a few kicks later it was running... It backfires abit though.. not real loud, but alot sharp sputters... also after it ran alittle oil came out or one of the hoses in the bottom this normal? thanks ?

[spc mike]

some race fuels will leave a residue like you discribed.

[grayracer513]

some race fuels will leave a residue like you discribed.

So will AvGas.

[aj_yz426]

also after it ran alittle oil came out or one of the hoses in the bottom this normal? thanks ?

a lot of oil coming from the breather hose left side bottom of frame is usually a sign it was overfilled last oil change otherwise normal for alittle to condense in the tube and drip out. Look up rerouting the oil breather tube, it can suck up water/mud if you try to start the bike after stalling in water.

[Chriswells85]

Ive only ever used "Supreme" or w/e from the pump, never any high octane or racing fuel, Does the regular run better in these bikes? Also, should i get a new Jet kit and install it? as far as i know this has never been done...

[grayracer513]

Does the regular run better in these bikes?

No. Your bike requires a minimum US pump grade of 90-91. Detonation and possible severe engine damage can result from using lower grades of gas under the wrong conditions.