Hooray another jetting thread 04 450

[x_JT_x]

Ok so I am a total dork when it comes to jetting. I can play around with main and pilot a little but not these fcr carbs. My 04 wr450f just got upgraded to a FMF muffler from a stock with gytr tip. It's running a cut out airbox intake, I think I have the tps unplugged as it was giving me issues, and is otherwise pretty stock.

Current jetting is 165 main jet 45 pilot 65 other jet next to those two.

Most of my riding will be done around 1500' elevation.

Currently, at around sea level (100') I have the fuel screw bottomed out for best idle. Now to me this would indicate a rich pilot but at 45 it seems good.

This is a bad aluminum mix screw as a lot are. I would like to know what jetting would be best to put in this? Different needle? I honestly don't really even know needle position. Maybe dead in the middle if I recall.

The pipe came from a wr250 but the pipes are the same so it shouldn't matter.

The mix screw will get an update eventually.

Any help much appreciate!

[FORMA MOTO]

HOORAY!!

[FORMA MOTO]

Change the fuel screw to an R&D first 

 

165

45

NCVS needle 3rd

50 leak

...is fine

[x_JT_x]

Change the fuel screw to an R&D first

165

45

NCVS needle 3rd

50 leak

...is fine

I don't believe the 65 jet is the leak jet, is it? I've had so many carbs apart lately I'm all mixed up. Leak jet will be in the float bowl, not the carb body?

Ncvs needle it is. No clue what the stock one is, so Google here I come.

I had heard the flexjet had some issues with not actually being precise with the amount of turns. If that's not true I'll order one right up.

[FORMA MOTO]

Flex jet is the schiznit

 

leak jet is in the bowl

[x_JT_x]

Well I ordered the needle and flexjet. The leak jet is out of stock everywhere so that will be interesting.

[x_JT_x]

On a side note, this fmf muffler mid pipe comes really close to the plastics. The other wr I ride with it contacted it and melted it.

[FORMA MOTO]

You can order the leak jet from any mx brand dealer

You can order it from jets r us

 

Put reflective  tape on the backside of the plastic

[x_JT_x]

The 50 is out of stock everywhere I have looked. They have the 30-45 range stuff but not the 50.

There is reflective tape. It did it once to the stock plastic then once to an aftermarket one. It's like a design flaw with the fmf. I decided to put two spacers between the lower muffler mount and frame, it moved it enough where the plastic will take some pressure to touch the pipe now. That should fix it, hopefully.

Someone should remake all the stock decals for the wr's. Fender decal, the one that says "titanium 5 valve", head light one etc etc.. I'm a big fan of the OEM look and it's going to bum me out if I can't get those replacements when I change plastics.

[FORMA MOTO]

All of the decals are available from Yamaha, but they are pricey

 

A 45 leak jet or a 55 leak jet is fine

[x_JT_x]

All of the decals are available from Yamaha, but they are pricey

A 45 leak jet or a 55 leak jet is fine

One question though, how is my current jetting good if I have the fuel screw bottomed out to achieve the best idle? Ca the needle cause that? My hot start is all good. New plunger o ring, new plaatic nut.

[FORMA MOTO]

You HAVE TO PUT IN THE PROPER FUEL SCREW.

 

Follow the advice and stop guessing.

[x_JT_x]

Ok. Every wr I've seen all ran the alum screw but maybe mine is messed up. I'll post an update when the new one gets here.

I've actually never seen anyone use the flex jet. Worth the $30 for the ease of tuning it looks like though.

Mine looks like one of the basic ebay fuel screws.

[FORMA MOTO]

Yeah, you have mentioned that a few times already.

 

THEY ARE TAPERED so you can't ever tune properly with them.

 

THEY ARE ALUMINUM so they corrode and break off inside the carb....!

[x_JT_x]

Yeah, you have mentioned that a few times already.

THEY ARE TAPERED so you can't ever tune properly with them.

THEY ARE ALUMINUM so they corrode and break off inside the carb....!

I wish sellers would stop selling them. For the majority, we won't know they are bad.

On a better note the new one will be in in a couple days.

[x_JT_x]

Well, I got the new parts installed. Crisper throttle, but the fuel screw still has to be in all the way to achieve highest idle.. I am stumped. And that is at 200f elevation. Wouldn't I have to take the screw in even farther once it's at 2000 feet?

[FORMA MOTO]

You have a false rich symptom

Check you choke plunger to make sure it is bottoming

[still2smokin]

Krannie knows his stuff for sure....

 

On my 05 , I run

 

168 main

48 pilot

40 leak

4th clip down on JD Red needle

1 1/2 to 2 turns out on an R&D flex fuel screw

 

and some how it is pretty consistent from 1000 to 8000 feet

 

If I turn my fuel screw all the way in the bike will not idle at all telling me something is amiss if

your bike will still idle .

 

Maybe check the Oring on your choke plunger .

 

Also super important is your accelerator pump squirt timing for crisp throttle response .

 

[x_JT_x]

The throttle has no bog now, it's really crisp just seems wrong with the fuel screw bottomed out. I'll take a look at the choke plunger, and post my findings.

I did the oring mod while I had it apart. apparently the previous owner tried his own version of this using basic wire? The stuff used to hold grips on..

Since I won't get a chance to check the choke plunger for a few hours, what are some other things I should look at while I check the choke?

*edit*

Fixed auto correct failure.

Edited February 8, 2015 by x_JT_x

[FORMA MOTO]

You have very few other sources for a rich condition....

 

Pilot air jet in the intake bell can be damaged ofr partially clogged

Your ACV valve can be stuck (never actually seen that happen)

Your air filter can chock full of dirt, or way over oiled...

Your needle jet can be ovaled (worn out)