Jetting for my New FCR Conversion (DRZ400S)

[nondem]

http://www.linearrow.com/keihinfcr.jpg

I've got this carb and the parts to make it fit my 04' DRZ400S are on the way.

AFAICT this is the newer FCR39MX that has the internal pump, vertical slide and is larger than the old style. Do the same jetting rules apply? I've previously done the Burned jetting/3x3 on the BSR36Cv and after following his advice to the letter I did'nt even need to make any further adjustments.

I would appreciate any jetting/setup advice for this carb from Burned or anyone who wants to offer their opinion. I have a buddy with a variety of jets for this carb laying around but no needles. Should I get a jet kit or a different needle?

This is going on DRZ w/a full FMF system and I plan to install hotcams once I've paid for this

[Wayward Son]

what needle does it have?

[James_Dean]

Is the carb from a Yamaha YZ or WR450?

Check the pilot jet and air jet sizes in the inlet to the carburetor. The WR has smaller air jets, but also has an Air-Cut valve making the idle mixture leaner. The '05 WR450 carburetor needle only has 1 clip position too.

James

[nondem]

This carb is off a 2005 YZF450 quad. Here is a pic of the actual carb if it helps - it's a new take-off carb. http://www.linearrow.com/keihinfcr.jpg

I dunno what needle it has in it stock....

This one will need the following mods from what I'm hearing:

Trim frame for clearance or tilt carb(I'll trim)

Removal of the throttle cover

tapping return cable hole(optional)

removal of TPS

tapping a hole for the idle-adjust screw.

installation of a vacuum nipple for the petcock(or change to E type)

I'm beginning to think I might be better off buying another carb and selling this one. Do you guys agree? I've already ordered all the OEM parts for the conversion so i could just find another FCR to plug in.

Either way - I plan on putting the jets/needle/kit in it you guys recommend before I install it on the bike.

[Wayward Son]

Trim frame for clearance or tilt carb(I'll trim)

you will need to trim the carb.

Removal of the throttle cover

yes,for sure.

tapping return cable hole(optional)

that carb only has a pull cable?thats ok.i dont have a push cable on any of my bikes.

removal of TPS

why not just plug it in?

tapping a hole for the idle-adjust screw.

it doesnt have a idle screw?

installation of a vacuum nipple for the petcock(or change to E type)

just go to a manual fuel valve.you will thank me later.

I'm beginning to think I might be better off buying another carb and selling this one. Do you guys agree? I've already ordered all the OEM parts for the conversion so i could just find another FCR to plug in.

ive always reccomended the old style fcr.much less of a head ache to fit.

[nondem]

The important issue to me is the jetting. Is this carb functionally identical to the old type - IOW would the same jetting setup used on a old carb work on the new one on the same bike?

[nondem]

I forgot to mention - there is another guy doing this with the same carb and the issue w/the idle adjust screw is described here in his PM to me:

-----------------------------------------------

I put the tps/idle screw assy. on the carb and there is no room, the idlescrew is hard into the frame, I found a tap and its on the way, I am going to order the flex adj. cable for the YZ450F just to make sure it has the same threads

[imlostagain]

Sorry to pirate this thread but ....I was hoping Burned would explain why to use a manual fuel valve instead of the vacuum fitting and stock petcock? Where might we find a manual fuel valve ... will the E/K models fit or are there other options ?

[Wayward Son]

the vacuum fuel valves are unreliable and cuase clearance issues.

[nondem]

If you find a suitable replacement please let me know. I'll be switching to a non-vacuum type too.

[Wayward Son]

E/K petcock or pingle.