19 seconds at top speed

[Sweet tooth sensation]

19 seconds of top speed and the FCR 40 bowl is sucked dry. Its off a CRF250R ,will anyone concur that I need a bigger float needle seat ? If so should I order the one that the CRF450R uses ?

[bumtarder]

Are you sure it's a fcr?Keihin never made a 40 that I'm aware of,usually 33,35,37,39 and 41mm.

Should be able to flow fine even at wot.Check to make sure gas tank is venting.

[Sweet tooth sensation]

Yes ,FCR 41 ,i put a rapter petcock on,maybe that is the problem ?

[Beta300REcat]

Disconnect the fuel line from the carb and run it into a jar to check the flow.

[Sweet tooth sensation]

From the rapter petcock, I used the stock hose and its making a sharp turn down to the FCR 41. That looks like problem. I'll buy a longer hose .Has anyone routed the hose aroun the boot?

[ohiodrz400sm]

At 1 point or another , both the CRF250R and 450R have used the FCR-MX 40mm. It is a more refined carburetor than what the other OEM's and aftermarket get. 1 benefit is they redesigned the accelerator pump actuator, eliminating the need for the o-ring mod.

 

Take a picture of the accelerator pump actuator so I can see what you have.

 

If you use the E model petcock then you can also use the E fuel line and it fits like it came from the factory that way.

 

Also, you need to take the carb back off and look at your float level and see what size leak jet you have( if it is a Honda 40mm) If it has a leak jet you'll need to use something smaller than the stock 70. I remember reading that the Z400 guy were using 55 leak jets.

 

 

 

 

 

 

[ohiodrz400sm]

This is the accelerator pump arm on a updated Honda FCR. The screw is on the left and arm on the right.

 

On the other FCRs the 2 are reversed

 

 

[BTD123]

Let's not rule out the fuel filter.

[Sweet tooth sensation]

Yes the carb is the same one as on my CRF450R, no O ring mod needed. The rapter petcock is brand new and only noticed the problem after installing it. Its almost as hard to get the tank on as the stock petcock is ,it interferes with the hot start boot on the FCR40MX .I got a hot start lever kit from Magura and made a bracket to mount it on the clutch perch .I will also check the leak jet ,thank you !

[jjktmrider]

You won't really need the hot start on the Z , maybe once in a great while after a spill . I plugged my hot start with a Yamaha YFZ unit that's on their fcr's . I also then used the hot start lever and cable (crf250) and put the choke plunger on it with the billet nut and now have my choke up on the bars , I'll never go back to the hidden knob on the carb that I could barely use because it hit the petcock right as it got to full choke . Did it on my 3 FCR biikes .

 

My guess as to why your running out of gas is because your fuel line is kinked off and limiting flow . That crappy setup with the outlet coming out right toward the carb is just asking for trouble so I went with a downward outlet petcock and kept my hose nice and free . The E petcock is probably the best solution .

 

.

Edited May 14, 2017 by jjktmrider

[Sweet tooth sensation]

Great idea with the choke ! I will order the E petcock . Anyone need a slightly used rapter petcock ? If that doesn't wor5 ,I'll check into the leak jet .

[bumtarder]

Nothing wrong with the stock vacuum petcock either and they're easily serviced.

[Sweet tooth sensation]

Yes I, was just looking for a little more clearance for the FCR40MX hot start boot .if the E petcock doesn't have any more clearance than stock , I  could put it back on today . Has anyone's K n N filter started  deforming under the clamp pressure? 

[ohiodrz400sm]

Yes I, was just looking for a little more clearance for the FCR40MX hot start boot .if the E petcock doesn't have any more clearance than stock , I  could put it back on today . Has anyone's K n N filter started  deforming under the clamp pressure? 

Throw that over priced pos away. Use a good quality foam filter.
I have a KN I bought, put on, rode around the block and took off. If you send me a brand new Uni or Twin air filter I'll send you this one. That applies to anyone interested.

[bumtarder]

Nothing wrong with the stock filter or the NAPA no-toil units either.The k&n just doesn't seal right even with filter skins imho.

[Sweet tooth sensation]

Gas flows good from the petcock.so I didnt change it . Just ordered a #55 leak jet. Are those guys running stage 2 cams and big bore kit like I am ?

[ohiodrz400sm]

I used too.

Is that a 125 or 140 pitbike?

[Sweet tooth sensation]

125 ,but i just installed a 146cc big bore kit last Friday with a new carb. You think the 55 leak will be good on MY DRZ  setup?

[ohiodrz400sm]

125 ,but i just installed a 146cc big bore kit last Friday with a new carb. You think the 55 leak will be good on MY DRZ  setup?

Nice. I have a 140 with the 146 hi compression head gasket in a CRF70, she rips.

Anyway, 55 is what I read, I haven't tired it. I bought and was going to install a 40 on my bike just to see if there was a difference but the opportunity came to sell for a little profit and I took it. The aftermarket FCR's don't have a leak jet, the DRZ can handle the full squirt without bogging like the smaller bore bikes but since you have the ability to dial it in perfect you might as well take advantage of it.

[Sweet tooth sensation]

Still dialing in the pitbike mikuni ,ordered a smaller pilot for it along with that 55 leak. Would the wrong leak cause me to run the bowl dry in the Drz at top speed ?