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mcpga

WR450 needle question

16 posts in this topic

I read somewhere that the NCVS yamaha part# 5TA-14916-VS-00 needle was a good needle for an 03 wr450, is this correct? I looked up this part number and it shows it fits the YZ450f, again is this the correct needle?

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Just one carb part does not a good running vehicle make.

The NCVS is less tapered at the bottom third compared to the JD Red needle.

Depending on all the other factors, one might be better than the other.

Just the difference between a No Toil filter with No Toil oil vs a Uni filter with Bel Ray oil will make one needle work better than the other.

I like the open cell, multi layer UNI filters, because they stay cleaner (less restrictive) longer; therefore, the richer JD Red needle works better for that.

But....if your ACV is not sealing properly, or your Air jet is clogged or corroded, then you need the NCVS. It's leaner from the start.

Or....if your bike has YZ cams, which tend to create a small flat (rich) spot, the NCVS works better.

Needle

Pilot

Jet needle

Needle jet

leak jet

apump diapghram

apump linkage spring

apump timing

Gotta do em all....

I always recommend the NCVS needle because it is slightly leaner than the JD Red at 1/4 throttle, but way richer than stock.

Edited by Krannie

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My bike is apart right now as I'm waiting on some parts for my carb. New gaskets, new AP diaphram and o-rings, float needle, r&d fuel screw etc... I bought the bike used and Im just getting around to taking it apart. Here is what I know so far. The grey wire is cut, shortened throttle stop, 160 main jet, 48 pilot, needle clip in 4th groove, but I have no idea if its the stock needle, the air box snorkel in place, fmf power bomb header, stock silencer with billet insert. Before I put this thing back together I want to change the main to a 165, 45 pilot, 50 leak and change the needle to NVCS needle 3rd groove. All of that is based on what I have read on TT. I honestly, know nothing about 4-strokes, so I'm trying to educate myself on how to work on, tune and maintain these things. So thank you guys for your advice. Krannie seems to be "the guy" who knows what's up...

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Krannie is a know-it-all dick. Ask anyone.

Remove the snorkel

A 165 may be needed with the stock pipe with Billet SA end cap. Still restrictive (but not in a bad way).

If you open the throttle wide open above 5k rpm, and you fall on your face, it's needed.

The needle will be stamped with it's jet number, unless it's a JD, then it has a red, green, or blue colored top.

If it has any other markings on it, it's probably a dynojet or a fmf jet. Destroy it....!

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Come on now Krannie, I don't believe my bike has a small, flat spot since adding the cams. :-). At least, not the way I ride it.

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The leak jet is a 70, I want to change it to a 50 but havent been able to find one online yet. I ordered a NCVS needle that I'll start in the 3rd position, a 165 main, 45 pilot, all others stock. Replacing float needle, all gaskets and o-rings and AP pump diaphragm. Installing R&D fuel screw, cleaned everything, all passage ways are clear, removed air box snorkel, installed new twin air filter, new plug and lastly I need to do check the AP timing and upgrade the AP linkage. Is that it?

Edited by mcpga

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The leak jet is a 70, I want to change it to a 50 but havent been able to find one online yet. I ordered a NCVS needle that I'll start in the 3rd position, a 165 main, 45 pilot, all others stock. Replacing float needle, all gaskets and o-rings and AP pump diaphragm. Installing R&D fuel screw, cleaned everything, all passage ways are clear, removed air box snorkel, installed new twin air filter, new plug and lastly I need to do check the AP timing and upgrade the AP linkage. Is that it?

You upgrade the linkage spring with a R&D (stiff) Merge (medium) or an oring wrapped around it (absurd).

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Put new parts on carb today, but before reinstalling the carb on the bike I wanted to see if I could check the squirt timing so I put my gas tank on the bench hooked the gas line to the carb and turned the throttle linkage by hand. I did not see any squirt and not sure if this method will even work. Next I took the bowl off with AP still installed, filled the bowl with gas, put my finger over the port on top off the bowl to create suction, then using an old push rod pushed down on the diaphram and got gas to shoot out of the hole on the bowl, so my assumption is the pump is working correctly. Next I shot carb cleaner into the port on the carb to see if I could get anything to come out of the brass nozzle. A small amount of cleaner came out and then nothing. If this thing is clogged how in the world can I clean it out... Advice please!

Edited by mcpga

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Put new parts on carb today, but before reinstalling the carb on the bike I wanted to see if I could check the squirt timing so I put my gas tank on the bench hooked the gas line to the carb and turned the throttle linkage by hand. I did not see any squirt and not sure if this method will even work. Next I took the bowl off with AP still installed, filled the bowl with gas, put my finger over the port on top off the bowl to create suction, then using an old push rod pushed down on the diaphram and got gas to shoot out of the hole on the bowl, so my assumption is the pump is working correctly. Next I shot carb cleaner into the port on the carb to see if I could get anything to come out of the brass nozzle. A small amount of cleaner came out and then nothing. If this thing is clogged how in the world can I clean it out... Advice please!

Using REAL carb cleaner, spray up into that angled passage to the apump nozzle for one second.

Let it sit 10 min and repeat.

Keep doing this until the spray finally comes out of the brass nozzle.

As soon as it does, clear it with spray brake cleaner.

Oh, and real important: Keep your throttle held wide open the whole time (I zip tie the throttle tube open), and wash out the 'real' carb cleaner from the rest of the carb immediately after spraying real carb cleaner, with spray break cleaner. You don't want the 'real' stuff to get inside the body, or in the area of any rubber, as it will melt.

Having the carb off the bike and upside down ensures this....

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Damn! I had no idea tha carb cleaner would melt rubber, that's probably what destroyed my AP diaphram. I was spraying that stuff everywhere. I have been spraying up that slanted passage way for over an hour and still cant get a single drop to come out, I also lightly pushed a thin wire up the hole and I hit something that made a lil air and cleaner shoot back out. I'll keep trying! Sure hope I get to ride this Summer...

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Never ever use automotive carb cleaner on a MC carb.

You can and will melt the rubber seal inside the carb.

You spray brake cleaner and compressed air.

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Got the ap nozzle cleared using your method and a small piece of guitar wire that I poked through the ap nozzle opening, but still no squirt. Now it appears that the check valve in the bowl maybe stuck, the small bearing moves but will not spring back all the way to the bottom. Can this be removed and cleaned without damaging it?

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Soaked it all day, the ball still moves freely but still will not drop all the way down to the seat. I assuming if this check valve isn't working I'm not going to get any pressure to the nozzle, resulting in no squirt...

I'm guessing my only options at this point are to knock the check valve brass plug, spring and ball out and hope I don't damage it, then try to figure out if something is in there thats not letting it work properly, if I can't or if I damage the valve parts or bowl getting it out I'll spend $80 on a new R&D Power Pump which I'm pretty sure eliminates the check valve all together! Damn this is aggrevating!

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Soaked it all day, the ball still moves freely but still will not drop all the way down to the seat. I assuming if this check valve isn't working I'm not going to get any pressure to the nozzle, resulting in no squirt...

I'm guessing my only options at this point are to knock the check valve brass plug, spring and ball out and hope I don't damage it, then try to figure out if something is in there thats not letting it work properly, if I can't or if I damage the valve parts or bowl getting it out I'll spend $80 on a new R&D Power Pump which I'm pretty sure eliminates the check valve all together! Damn this is aggrevating!

Yup. Pain in the butt. Gotta use gas treatment everytime, all the time.

It sounds like cast aluminum seat that the ball sits on it corroded.

I have 3 or 4 stock FCR bowl covers if you are interested. I use the R&D PB III on my dual sport bikes, so I have essentially brand new ones.

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