Install/jetting feedback for Keihin FCR on XR650L


13 replies to this topic
  • Brtp4

Posted October 22, 2007 - 05:13 PM

#1

I have Dave's mods and they are good, but my CV carb still sucks for throttle response, so I am putting an FCR 41 on my 06 650L. I live in Bend OR, at about 3400', and many rides go up in altitude from here.

Stock piston and cam, desmogged, Pro Circuit 496 slip-on pipe.

I got the baseline from Burned, but I'm looking for comments and jetting info from you all. Anyone have any feedback?

BP

ride.race.live.

  • machman

Posted October 23, 2007 - 06:18 AM

#2

I have an uninstalled FCR for my highly modded XRL at 3000'. I too am very interested in hearing a response to this question. I'm also interested in hearing what baseline was recommended to you.

Here's what I've researched so far:

at 4300':
55/160 worked well
55/158 is ideal
52/158 was slightly lean

at sea level:
Main jet..............#170
Needle................OCEMR
Needle clip...........5th position from top
Float level...........9mm
Slow air screw........1.0 turns out
Main air jet.........#200
Pilot jet.............#48
Idle mixture screw....2 turns out

  • martinfan30

Posted October 23, 2007 - 12:46 PM

#3

my fcr is the same as your bottom list machman except i run 158/52, 1 and 1/4 turns out. i live a t 4300 ft. it runs very good. i also run a pod filter. no airbox conection cuz the battery sits in there.

  • Brtp4

Posted November 01, 2007 - 06:25 PM

#4

OK< so I finally got this on and think I have it dialed in. Notes:


- Once again, DO NOT use the Sudco jetting, it will be way off. Instead contact Burned and get his recc's as a starting point.

Fit is not great. Overall carb length is about 5 mm too short, so you have to pull the boots on and then tighten. OD of bell on engine side could be 1-2 mm larger and clamping would be better.

- I am at 3300'. Bike is an 06 XR650L with PC 496 pipe, desmogged. Jetting is nearly spot-on, at the following settings:

160 main jet
200 main air jet
emp needle
clip 3
45 pilot jet
Pilot air screw conversion at 1 turn
fuel screw 2 turns out

Jetting is spot on. No bogs, hiccups, stumbles, etc. It is definitely faster than it was but it is still not even close to an R. However, the real benefit is not the additional power, it is the throttle response and the way it builds revs. The stocker felt dead, w/the FCR it is more responsive, and actually easier to ride.

All in all, it's a good upgrade, but somewhat expensive. I am approaching $6500 into this bike and that is a lot for 15 year old tech, 330 lbs., and slightly better than 50 hp per liter. On the other hand, it will likely go 20k miles w/o rebuild, decent both on and off road, and it is street legal.

BP

I have Dave's mods and they are good, but my CV carb still sucks for throttle response, so I am putting an FCR 41 on my 06 650L. I live in Bend OR, at about 3400', and many rides go up in altitude from here.

Stock piston and cam, desmogged, Pro Circuit 496 slip-on pipe.

I got the baseline from Burned, but I'm looking for comments and jetting info from you all. Anyone have any feedback?

BP

ride.race.live.



  • martinfan30

Posted November 01, 2007 - 09:08 PM

#5

brtp4, sounds like you have the mx fcr (straight body) carb. judging from your fitting issues. my slant (side draft) fcr fits perfectly with no pulling of the boot.

only difference in jetting i see is i use the EMR needle and a 52 pilot(2 turns out on the fuel screw).

i'm curious what you mean by "air screw conversion at 1 turn out"?

arent air screws before the slide (int side) only on 2 strokes?

  • August West

Posted November 27, 2007 - 06:11 PM

#6

Howdy y'all! My first post on TT...I was steered over here by Brtp4 from ADvrider.

I'm considering the FCR-41 for my 1993 XR650L...the last post brought up the sidedraft versus the MX FCR-41. Are there differences between the two?

Thanks Brtp4 for the heads-up!

  • martinfan30

Posted November 27, 2007 - 06:58 PM

#7

ya the mx fcr is a straight body and the one i have is the slant body.

i have the EMR needle, how is the EMP needle different? anyone know?

i also have heard the non mx fcr is not avail. with a choke(no prob. with a little richer pilot). also fit is better with the non mx.

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  • Brtp4

Posted November 27, 2007 - 09:47 PM

#8

ya the mx fcr is a straight body and the one i have is the slant body.

i have the EMR needle, how is the EMP needle different? anyone know?

i also have heard the non mx fcr is not avail. with a choke(no prob. with a little richer pilot). also fit is better with the non mx.


MF30, on the needle I don't know. Just went with Burned's reccommendations, and they seem to be dead-on.

To me, the best point about the FCR is the squirt, really helps the throttle response. So, MX version or non-mx probably has little performance difference, and the choke is not needed. If the fit of the MX was better, that would be important though.

  • August West

Posted November 28, 2007 - 05:06 PM

#9

Called Sudco and talked to Curtis and order the 650L kit, which includes "pre-jetted carb, bolts to stock intake and air box, also includes Motion Pro cables that utilize the stock throttle" and ordered a 45 pilot as well. Not sure about the main pilot air, I think it's a 100 but wondering if I should order a 200 as well? Cost of kit was $516. The unit is the slant body and not the MX. Could get the MX but would have to pay for all the extras mentioned above, pushing the price over $700, with possible fit issues as the MX is physically larger. Will get carb on Friday for a weekend installation!

  • martinfan30

Posted November 29, 2007 - 07:37 AM

#10

Called Sudco and talked to Curtis and order the 650L kit, which includes "pre-jetted carb, bolts to stock intake and air box, also includes Motion Pro cables that utilize the stock throttle" and ordered a 45 pilot as well. Not sure about the main pilot air, I think it's a 100 but wondering if I should order a 200 as well? Cost of kit was $516. The unit is the slant body and not the MX. Could get the MX but would have to pay for all the extras mentioned above, pushing the price over $700, with possible fit issues as the MX is physically larger. Will get carb on Friday for a weekend installation!


the one i got from them(same as yours), had a 170 main, 60 pilot, 200 air jet.

WOULD NOT RUN!!

all i changed was i went to 158/52. also buy an after market fuel screw, cant adjust with out it when carb is installed.

  • richar_92692

Posted January 13, 2008 - 08:52 PM

#11

I live in on the coast - southern cal. Just did current mods to my bike - desmoged, whitebross e2 pipe, snorchel removed, uni air filter. working on dave's carb modes and trying to find out optimal jet size without experimenting too much. is there anybody from same area and same bike who already done this and can advise? I bought 55/158, but the main jet is to tall, so I will have to go exchange it and also I might go for different size - heard sometning about 58/160 works good??? Please let me know
thank you:ride:

  • xr650l bum

Posted January 14, 2008 - 05:56 AM

#12

I live in on the coast - southern cal. Just did current mods to my bike - desmoged, whitebross e2 pipe, snorchel removed, uni air filter. working on dave's carb modes and trying to find out optimal jet size without experimenting too much. is there anybody from same area and same bike who already done this and can advise? I bought 55/158, but the main jet is to tall, so I will have to go exchange it and also I might go for different size - heard sometning about 58/160 works good??? Please let me know
thank you:ride:


Where in Socal? When you say to tall, do you mean you got the wrong jet? 58/160 is a good starting point.

  • martinfan30

Posted January 14, 2008 - 08:18 AM

#13

160/55 or 158/55 are good choices for a cali elevation bike.

  • richar_92692

Posted January 14, 2008 - 08:25 AM

#14

I live in mission viejo, orange county





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