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R&D Flex Jet Fuel Mixture Screw
R&D Flex Jet Fuel Mixture Screw

$36.99 $39.95
7% Off - Save $2.96

Select your bike to see if this fuel mixture screw fits
Description See Also: 78 Reviews 4 Questions Fitment Part Numbers
Item #RND0001

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78 Reviews
4.7 out of 5 stars
5 Star   65 4 Star   9 3 Star   1 2 Star   1 1 Star   2
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All Reviews
MotoSport Staff Verified Purchaser
Portland, OR, USA
Durability 5/5 Ease of Installation 5/5 Performance 5/5 Style 5/5
Best on the market

I am just replacing the one that has been on there for 10 yrs now so you know I like it. Beauty of it is, you can adjust your air fuel screw while never getting off of the bike. Perfect.

Verified Purchaser
NE Ohio
Durability 4/5 Ease of Installation 5/5 Performance 5/5 Style 5/5
Super easy to use!

Does exactly as it should. Takes 5minutes to install, and can be adjusted sitting on the bike if needed. Overall great product!

Durability 4/5 Ease of Installation 1/5 Performance 3/5 Style 4/5
Please Read if buying for Yamaha 4stroke!!

I bought this part(R&D Flex jet fuel screw) for my 1998 YZ400F. To begin, as soon as i opened up the package, i noticed the flex jet was completely out of its box. I wasn't sure if maybe it had slipped out during shipping or a careless motosport employee had just thrown it in the box. Upon further review, the cardboard box looked just fine, and after looking at the flex jet part box, it was obvious that it had already been opened and the decal that says its included with the flex jet was no where to be found. I don't care about the decal but the fact that i paid almost $40 for this part just to be throwed into a cardboard box, not to mention the washer and o-ring are tiny and could have came off the flex jet and i probably wouldn't have found them but thankfully they were still attached. Here's the real problem though, this part is listed as an "exact fit" on the website for my bike, and it even says on the flex jet box that its an easy bolt on upgrade for ANY keihin FCR-Mx carb---This was not true for me!! i had to take the bowl off the carb to remove the old fuel screw, the fuel screw does not thread into the bowl, its threaded into the upper part of the carb so when i took the bowl off and removed the fuel screw, the flex jet would not fit through the hole on the bowl which guides it up to the threads. I had to take a drill bit and drill the hole out real lightly for the flex jet to fit through it in order to reach the threads. Other than that, the product seems of good quality and i would consider using one on any bike i own. I had already planned on buying plastics and graphics kit from motosport, but after having this trouble, im not so sure that this is where i want to spend my money.

Verified Purchaser
Central Oregon
Durability 5/5 Ease of Installation 5/5 Performance 5/5 Style 5/5
I don't know how people live without these.

This is literally one of the most important things you can buy for a carb bike. On the fly adjustment for when you are riding in areas with massive elevation change. It is a must.

Verified Purchaser
Durability 4/5 Ease of Installation 5/5 Performance 4/5 Style 4/5
Easy to use

Made tuning in the air screw way easier! No fumbling around with a screw driver and having the bike get to hot from ideling to long. Must have!

Verified Purchaser
East Bend
Durability 5/5 Ease of Installation 4/5 Performance 5/5 Style 3/5
The only fuel screw I will ever own

This is such a great product. It is so easy to just reach down and tune your carb. It will never fall out like the last two aluminum ones I had. Don't waste your money on the colorful ones that will fall out somewhere on the trail or track. Spend a little more and get this one, it's more than worth it.

Verified Purchaser
Durability 5/5 Ease of Installation 5/5 Performance 5/5 Style 5/5

Verified Purchaser
Lyndhurst, Va
Durability 4/5 Ease of Installation 5/5 Performance 5/5 Style 4/5
One of my best purchases.

Flex jet mixture screw is a must have. If you are fumbling with screwdrivers, or burning your hands trying too adjust the fuel screw, you need this part. Super easy to install. My only gripe is: I wish the would wrap a rubber band around, or tape the box it comes in. As in my case, the box came open & lost the small washer. Other than that, Great product.

Verified Purchaser
Durability 5/5 Ease of Installation 3/5 Performance 5/5 Style 5/5

Whoa! Gave my bike too much power. I literally can loop out in 7th gear every time now. I highly recommend this if you are looking to holeshot the finish line jump every single lap in reverse.

Verified Purchaser
Durability 5/5 Ease of Installation 4/5 Style 5/5
Great product

At first was a little difficult to adjust but then got it to adjust. Works great, idle is the best its ever been ony 2004 RMZ 250!

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4 Questions
Answered:   4
Not Yet:   0
R&D Flex Jet Fuel Mixture Screw
Q: Does this fit on a pit bike?
Over 3 years ago
Does the crf 70 fitment fit on a 125cc pit bike engine? lifan and all of them engines? the fuel mixture screw for my VM26 carb is under the bike so its hard to get at, would it fit on a VM26 Mikuni? and if so which do i order?
MotoSport Staff Expert
Over 3 years ago
A: No the R&D Flex Jet Fuel Mixture Screw will not fit the VM26 carburetor.
Q: Does the flex jet, adjust the fuel to air ratio??
Over 4 years ago
MotoSport Staff
Over 4 years ago
A: Yes, the R&D Flex Jet Fuel Mixture Screw will replace your stock (OEM) fuel/air mixture screw making it much easier to make adjustments with out having to use any tools.
Top 250
Over 4 years ago
A: This is a fuel mixture adjuster, and by decreasing your fuel you are increasing your air. You already have this screw on your carb, this item just makes it easier to access it on the track to fine turn your ride.
Q: Are there several different size/type flex jet fuel screws?
Over 4 years ago
I am trying to buy a flex jet screw for my 2000 drz400e I am aware that the flex jet screw is only made for fcr-mx and not the old slant style fcr's but I am aware of how to overcome this problem The only problem I have is that I was under the impression that there was only one flex jet screw, not several different ones. Does this mean that no matter what bike I pick from your list of comparable bikes i will get the same product? Or is there a difference
Top 250
Over 4 years ago
A: this is only one size and the bike list is just to see if it would fit your model. From everything I see it is not designed for your carb.
Expert MotoSport Staff
Over 4 years ago
A: There is actually only one Flex Jet. The website required a bike selection so that it won't be ordered for bike it does not fit. But you are correct that there is only one flex jet that is meant to fit FCR Carburetors. Since you have plans to use this on a bike that is not listed for fitment with this, you would simply want to select any bike this would be made for to order it, for example you could select a 2008 Suzuki RMZ450 and then the website will allow you to add the item to your cart.
Over 4 years ago
A: try their website

They might have something for you.
Q: I have a 2006 crf 450 and am having a hard time getting it started only on first start starts fine after warmed up. any ideas on carb adjustments?
Over 4 years ago
Over 4 years ago
A: Several things could be the issue but my son has the same year 250. Check your hot start operation to ensure it is not sticking. Also, the carb does have an fuel pump diaphragm and if you give the bike 4-5 shots of throttle before trying it cold that helps. His bike starts cold with choke on 1st or 2nd kick. if this does not work, try some of the 4 stroke blogs. We have also installed the Boyesen QS2.
Over 4 years ago
A: Not so sure its a carb issue. Could possibly be valves are about due for some shims. But a good start is....on your fuel adjust screw, thread all the way in till it bottoms out , then take your fuel screw out 1 to 2 turns out. While running and warmed up slowly pull your hotstart the bike should idle up like the choke is on. Then you know your where you need to be on your carb adjustment. If you have had valves shimmed could be your start jet needs cleaned. Hope this helps.
See all bikes that this part fits...
See Fitments
# Part Numbers
Product Variant Manufacturer Part #
R&D Flex Jet Fuel Mixture Screw FLEX-TECH FUEL SCREW