2006 yz450f

[Finesse77]

So i acquired got a 2006 YZ450. It starts up fine but it only runs when the choke is on. When i turn off the choke, the bike dies. Does this mean that carburetor needs cleaning? And it back fires also.
Thoughts?
I haven’t mess around with it yet due to work schedule.
Any idea what could be the problem?
Thanks in advance

 

[Junkie]

the most likely scenario is a dirty pilot jet

 

[gixxerjeff]

Totally, totally, totally this^^^^^^^^

 

[Finesse77]

Thanks guys for the info. I’ll look into it.

 

[2strokeYardSale]

That's what my WR450F does when the pilot jet gets dirty. I drain the float bowl after every ride now.

 

[gixxerjeff]

That's what my WR450F does when the pilot jet gets dirty. I drain the float bowl after every ride now.

It could very easily need more than that.
I suspect *white death* due to ethanol in the fuel.
You may need to tear it down and clean the hell out of it.
Still an easy job.

 

[2strokeYardSale]

Oh for sure it needed a carb cleaning when it acted up. But I try to prevent that now by draining the bowl.

 

[gixxerjeff]

 

[Finesse77]

Decided to clean the carb myself. But how can you determine if the carb needs a rebuild or just clean?
So far so it’s going ok. I just need to get the carburetor out. I’ve done some research and most them say i need to take out the spring for easy access of the carb.
Now that it’s open, should i check the valve clearance as well? I know i might as well replace the spark plugs.
Any pro tips? Also, i wanna replace the tires. What’s a good tire for track riding and hill climb?
Hoping to get this running good before red season starts

 

[2strokeYardSale]

Checking valve clearance is pretty easy. Changing clearance will be more difficult.

Just clean the carb unless it's leaking, the float needle is worn, something like like that. Maybe if it's impossible to jet correctly. I heard these things wear out nozzles (needle jets).

My pro tip is to get an hour meter.

 

[OaklandF4i]

As already mentioned, its a lean condition that is the cause of the symptoms. Most likely a gummed up dirty carb and pilot. It could be other things, but thats where I'd start.

Any new to me used thumper gets the carb pulled and cleaned. Make note of the jets, needle, and position. Not everyone is capable of jetting... and some previous owners have gotten them thoroughly wrong. So dont assume its jetted correctly. If after you have cleaned the carb, believe the jetting is right, and the problem persists then you need to look for an air leak.

Check the valves. Keep notes if they have moved. Button up and do a compression and leakdown test on it. Dont be aftraid to pull head and jug to inspect further. Again, take notes and keep. Add hour meter.

If you dont know the history and hours on the head, crank, or piston, its worth spending the few extra dollars on gaskets to inspect them. I always keep some with my spares.

Get use to doing these tasks on a regular basis (valve check/compression/leakdown). Even if everything checks out now, you will have a benchmark to watch if anything changes. Be it the valves moving, your compression or leakdown figures dropping.... you will be able maintain and fix before an expensive failure.

Thats my pro tip. Its cheaper to maintain one of these motors than to repair after a failure.

 

[Finesse77]

Thank you all for tip and opinions. I pulled out the carb and cleaned it.
Next will be to check the valve clearance. I just found out the bike came with a hour meter.

 

[DONGLEE]

As said before, keep notes with hour meter readings and Normally you can just unbolt the top of the shock and it swings back far enough to maneuver the carb. I have an 06’ KX 450 and I believe they’re almost identical to the Yamaha. If you do need to adjust the valves I may have shims

 

[Finesse77]

So i finally got the chance yesterday to pulled out the carburetor. And my mistake was only to cleaned the bottom part of the carburetor. I looked at the top and said nah, it looks clean. So i just cleaned and bottom part and put everything back. And the same thing happened. Bike only ran when choke is on. And back fire. I almost gave up. But i took the carb again and this time i cleaned from top to bottom. And i think i found the problem. See pics... The O ring is broken in half. So maybe that’s the culprit. I will try to go to yamaha dealer tomorrow, hopefully they carry this in stock.
Also, i am putting new pilot jet and main jet. 168 main and 45 pilot.
What you guys think about this jetting. Will be riding mostly in Carneige and metcalf for now. And maybe Hollister.
Thanks

 

[OaklandF4i]

So i finally got the chance yesterday to pulled out the carburetor. And my mistake was only to cleaned the bottom part of the carburetor. I looked at the top and said nah, it looks clean. So i just cleaned and bottom part and put everything back. And the same thing happened. Bike only ran when choke is on. And back fire. I almost gave up. But i took the carb again and this time i cleaned from top to bottom. And i think i found the problem. See pics... The O ring is broken in half. So maybe that’s the culprit. I will try to go to yamaha dealer tomorrow, hopefully they carry this in stock.
Also, i am putting new pilot jet and main jet. 168 main and 45 pilot.
What you guys think about this jetting. Will be riding mostly in Carneige and metcalf for now. And maybe Hollister.
Thanks

I cant speak to what your bikes correct jetting is. If its withing a few sizes of stock it should at least run (and that seems to the case). Replace your worn/damaged parts, check to make sure your float level is right, not too low. Also make sure your fuel screw/passage is clean and not turned all the way in. Most bikes are somewhere between 2-3 turns out. Take your time to ensure all passages of the carb are clean and tubes are obstruction free. Also, assume you are starting the bike with your filter on and oiled (will run slightly lean without).

 

[Finesse77]

I cant speak to what your bikes correct jetting is. If its withing a few sizes of stock it should at least run (and that seems to the case). Replace your worn/damaged parts, check to make sure your float level is right, not too low. Also make sure your fuel screw/passage is clean and not turned all the way in. Most bikes are somewhere between 2-3 turns out. Take your time to ensure all passages of the carb are clean and tubes are obstruction free. Also, assume you are starting the bike with your filter on and oiled (will run slightly lean without).

Thanks for the tip. I just ordered the air filter (pre oiled)
I’ll make sure the float level is right. And i will do an oil change also.

 

[2strokeYardSale]

Also, i am putting new pilot jet and main jet. 168 main and 45 pilot.
What you guys think about this jetting. Will be riding mostly in Carneige and metcalf for now. And maybe Hollister.

Sounds about right. I think that's what's in my WR450F with a YZ450F needle in the middle position. Plus o-ring mod for the accelerator pump and a bleed jet or something. I don't know if the latter are "must do" mods for the YZF. Should be the same carb, same engine.

 

[DONGLEE]

So i finally got the chance yesterday to pulled out the carburetor. And my mistake was only to cleaned the bottom part of the carburetor. I looked at the top and said nah, it looks clean. So i just cleaned and bottom part and put everything back. And the same thing happened. Bike only ran when choke is on. And back fire. I almost gave up. But i took the carb again and this time i cleaned from top to bottom. And i think i found the problem. See pics... The O ring is broken in half. So maybe that’s the culprit. I will try to go to yamaha dealer tomorrow, hopefully they carry this in stock.
Also, i am putting new pilot jet and main jet. 168 main and 45 pilot.
What you guys think about this jetting. Will be riding mostly in Carneige and metcalf for now. And maybe Hollister.
Thanks

That kinda looks like this little guy.... I’m one of those weirdos that save old parts forever

 

[dbc]

45 pilot- Bike completely warmed up- Start with the fuel screw about 3/4 turn out, work from there.
I normally use a 42, screw 1 1/2~ 1 3/4 out.

Make sure to carefully check that vacuum release plate for signs of wear. Hopefully it's OK, about a 100 bucks to replace.
Remember which way is up when you reinstall it, lots of folks accidentally mount it upside down.
https://www.crfsonly.com/howto/keih...-to-replacing-floating-valve-seal-crf450r.php

He mentions using the correct Phillips screwdriver- Ever wonder, while working on your bike, that your Phillips screwdriver never fits properly and winds up stripping the heads, then blaming it on "Cheap OEM" screws? Actually the screws aren't Phillips, they're JIS (Different pitch). If you don't have a set of dedicated JIS screwdrivers, now's the time..
(They make great Xmas presents)
https://www.mcmaster.com/jis-(japanese-industrial-standard)-screwdrivers

Here's a good place for carb parts without breaking the bank.
http://jetsrus.com/

 

[Finesse77]

So i cleaned the carburetor from top to bottom. Replaced the floating valve seal, install a new pilot jet of 45 and new main jet of 168.
I started it up it’s still doing the same thing. Bike only runs on choke, back fire and dies when choke is off.
So i took out the carb again and inspect and clean again. While doing that, i noticed that the fuel screw is missing, as in nothing in there. Not even the stock fuel screw that came with the carburetor. I attached a pic.
Sorry for my ignorance, but how important is the fuel screw. Without it, would the bike run or dies. Like i mentioned before, i acquired this bike and don’t know the history.

 

[augustiron]

That is absolutely necessary, bIke will nor rUn wit out it. Get a steel extended screw so you can adjust it without tools.
Zipty or scotts make some.

There are a small spring, washer and o ring that go in there with the screw. Make sure the old ones aren't still in there when you install the new setup

 

[PASTAPWR]

That is absolutely necessary, bIke will nor rUn wit out it. Get a steel extended screw so you can adjust it without tools.
Zipty or scotts make some.

There are a small spring, washer and o ring that go in there with the screw. Make sure the old ones aren't still in there when you install the new setup

This!

 

[byke]

And that plate on the slide with the damaged o-ring, make sure you put it in the right way. It's easy to put it in upside down and you'd be chasing conflicting jetting symptoms foooreverrrrr.

 

[OaklandF4i]

45 pilot- Bike completely warmed up- Start with the fuel screw about 3/4 turn out, work from there.
I normally use a 42, screw 1 1/2~ 1 3/4 out.

Make sure to carefully check that vacuum release plate for signs of wear. Hopefully it's OK, about a 100 bucks to replace.
Remember which way is up when you reinstall it, lots of folks accidentally mount it upside down.
https://www.crfsonly.com/howto/keih...-to-replacing-floating-valve-seal-crf450r.php

He mentions using the correct Phillips screwdriver- Ever wonder, while working on your bike, that your Phillips screwdriver never fits properly and winds up stripping the heads, then blaming it on "Cheap OEM" screws? Actually the screws aren't Phillips, they're JIS (Different pitch). If you don't have a set of dedicated JIS screwdrivers, now's the time..
(They make great Xmas presents)
https://www.mcmaster.com/jis-(japanese-industrial-standard)-screwdrivers

Here's a good place for carb parts without breaking the bank.
http://jetsrus.com/

And that plate on the slide with the damaged o-ring, make sure you put it in the right way. It's easy to put it in upside down and you'd be chasing conflicting jetting symptoms foooreverrrrr.

That is absolutely necessary, bIke will nor rUn wit out it. Get a steel extended screw so you can adjust it without tools.
Zipty or scotts make some.

There are a small spring, washer and o ring that go in there with the screw. Make sure the old ones aren't still in there when you install the new setup

++++ 1 Bike wont run right.

Tusk also makes a extended fuel screw for $12. Makes tuning sooo much easier. In addition to making sure the old oring isnt still in there when you intall the new one, make sure actually use all the parts on the new one. IE oring, washer, spring.

 

[Finesse77]

Thanks guys. I just order a Fuel adjustment screw from Rocky mountain. Anxiously waiting.