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Have a johnny cash bike (stole it one piece at time...didnt cost me a dime...) apparently. Main frame and motor are 06, subframe was an 05, replaced it with an 06 so my exh midpipe would have something to bolt to. My idle has been really funky lately with the heat (100+ days) so I built a heat shield to keep the carb cooler. On tight trails it hunts for an idle and that gets kinda nerve racking with bike constantly lurching, sure wears my clutch hand out quick. Pulled my air filter out to clean it and it had separated at the seam...whoopsies. So bought a new air filter and its still running funky at idle. Pulled the carb last night, figured the idle air jet may have garbage in it since its right there by the intake boot. Nope, its clean. So pulled the bowl since I didn't have a clue what pilot jet and MJ was in it. I know it has the factory needle and in the 4th slot. Was in the 3rd but I dropped it(the clip, not needle) one position to fatten it up and have it run a little richer (cooler). Well the main jet and the PJ are way too big based on the 06 manual. So for grins I got out my dial caliper and measured the bore on the head side and bam...its 41mm FCR carb. Supposed to have a 40mm on it. So downloaded the 08 manual and realized that the MJ is right on point for the 41mm carb. 178 but the idle jet is a 68! the manual says 42 is right, and from what Ive read everyone goes to a 45. So since this is a 41mm should I go with the 45 or maybe a 48? Not sure if the bore will matter since the slide will be closed most of the way anyways at idle.

How do you do it? I have the old spring out and have hooked the Merge spring around the arm. Either I'm weak as a girl or that spring is too thick. Also as you tighten it, it binds on the post and then you can't fit the plastic lever into it. There has to be a trick, otherwise this is $20 wasted and I'll just re-wire it.

2008 KLX450, FMF power bomb header, FMF Powercore 4 muffler, Desmogged, Air box top off 1000'-3000' altitude. 40 - 80 degrees Fahrenheit. Humid during summer I ordered the KX NCVR needle. What clip position should I put it to? Had a 155 Main jet, seems way too lean. Should I go 165 or 170? Have a 42 and a 45 pilot, not sure which to use with NCVR needle. What leak jet should I run for best throttle response/least bog? Currently have size 50 leak jet, I'm guessing it's stock as it has the Keihin star symbol next to the number. Float is at manual recommended measurement. Any suggestions are appreciated, thanks

My klx400r/drz400e will not idle seems way too lean pops at closed throttle severe on deceleration. I've read hours and hours on TT and other sites for years before getting the courage to jet and fix my no idle hang idle and now I've made it worse jd jet kit 3x3 ce removed and 2 ports connected 1 plugged everything else the way i bought it used I recently found the o ring and washer was missing from the fuel screw Installed oe washer and oring from rmatvmc 1,500 to 3,500 elevation 2.75 turn fs 162 mj 45 pj Blue jd needle -4 I took a 180 mj out that someone installed but tbh it ran better before jd kit! It now has a bog sometimes that I didnt have with bottomed out stock needle and 180 mj I ride 100% offroad mostly single track or with my kid so slowish I'm ready to sell this green drz and go back to a 2t. HELP

Hey guys. Ive been running into some trouble with tuning my fcr carb on my 2000 Honda xr650l. Its desmogged, de snorkled and has a uni air filter. Ive spent some tme trying to tune it but after talking with some guys i was going way to rich. I followed thier suggested tuning of 158 main, 48 pilot, NCVT needle 3rd clip from the top. After doing that the bike fired right up, way better than any of my other trys but when it heated up it would want to die. When i tried taking it back around the block it had a bad bog when i opened the throttle (ive adjusted the AP circuit properly already and tested it). It was also backfiring alot and at one point just conked out. Any insight that would help me? Thanks!

Hey guys, I put a Mikuni TM40 on my XR600R and really like it, but I always wondered if the FCR might be better. I ran across this EBay listing for a new FCR style carburetor. It doesn't show as a Keihin brand. Anybody buy one of these yet? Its a good price but I won't buy if the quality isn't there. I bought another XR and thought I would try an FCR on the new bike so I have one of each. https://www.ebay.com/itm/Honda-CRF-450-R-CRF450R-Carburetor-Carb-2002-2008-NEW/122835304977?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20160727114228%26meid%3Dd8d46407b09b4518913684b5910695aa%26pid%3D100290%26rk%3D2%26rkt%3D4%26sd%3D253192404113&_trksid=p2060778.c100290.m3507 Any input?

I noticed on my DRZ this carb nipple isn't connected to anything and it spurts fuel every time I twist the throttle, even with the engine off. It's a Kehin FCR carb from the enduro model. Photo here The bike runs mostly okay but I'm having a possibly-related problem where the engine cuts out when I blip the throttle, especially at low revs. I wondered if this carb port had something to do with it, since it's connected to the accelerator pump (which would explain why I can't blip it). Can anyone tell me what the port is for and why it's squirting petrol? Any help appreciated.

Is this carb going to work OK for my FCR swap? I picked up this 39 FCR from an eBay seller in China. The guy had perfect feedback and communicated well, so I took the chance and bought it. It is new and unused. By the numbers stamped on the body (3900K eaf29) it was originally from a KTM 250 XCF-W USA.

I am running lean at idle and adjusting the mixture screw will not resolve it. I get a hanging idle and 99% sure its lean. I did the side cover off vs on run and no effect. Outside of the idle the bike runs strong especially on top. What should I change to add a bit a fuel at idle range of 1800-1900 RPM's. My Setup is below and I have a Full MRD and 3x3 and K&N. 160 main jet 200 main air jet EMN needle clip 3 45 pilot jet remove pilot air jet 2 turns fuel screw o-ring mod R&D Racing Flex Jet Fuel Mixture Screw Thanks so much for any help you can give, I am struggling.

Seeing some videos on 70 vs 35 leak jet. What is the best accelerator pump setting for crisp throttle response, no bogging when you twist throttle fast as you can? Right now my screw that touches the black accelerator arm is only out 2 threads. There is lots of play on the black plastic arm in the opposite direction. Here's some pics and video of the current setup. Thanks

I'll try and give the timeline as best I can. Got a good deal months back on a bike that had cold start issues, well starting issue in general but it got better while warm. Had some issue idling but it ran really strong when you got it up to speed. Tried cleaning the stock carb multiple times (ultrasonic cleaned twice, once by me, once by a shop) and it didn't really solve much. Checked valves and they're in spec, which it should have been for having 9k miles. Don't get me wrong, bike ran well but wasn't reliable enough while starting that I didn't trust riding outside of my local area. Bit the bullet and bought an FCR MX39 which was my plan anyways, and that solved quite a bit of the issues, but brought up more. Start is better but it still takes a while, especially when cold. Idle is steady but will drop and die if too low. I occasionally get this loud pop while trying to start, like gun shot pop. I also now have this hanging idle issue when decelerating or coming to a stop. I can fix it by blipping the throttle which then makes the idles drop. If my idle is set too low, it will drop too low and stall. From my research I think it's a vacuum issue, which is weird cause the tubes are all there and the petcock vacuum is plugged. Took the throttle cables off to see if they were sticking and causing the issue but the video proves that's not true. I also checked for any air leaks near the boots, not it. Pulled the carb last night and only checked the slide but noticed this wearing on the top right corner and this super odd bubbling on the pressure plate. For the start issues I've heard bad CDI, but I'm not sure. Anyone have any suggestions or help they could provide? I promise a beer on me if I'm ever in your area! Video 1: https://drive.google.com/open?id=0By7xlw5wWOLHRVNfbGhCcUxmWXc Video 2: https://drive.google.com/open?id=0By7xlw5wWOLHaFVrRnlXcVpQSFE

Ok guys here we go this is going to be a long story....... I purchased an 02 ktm 520 (mxc) about 3 years ago, bike ran but had starting issues.. I was told it had a new top end which it may have but the timing chain was fully stretched and I decided just to have the motor built (top, bottom,clutch)while I restored the chassis and components... I received the motor back probably almost a year later, put it the newly restored chassis and was never able to get the bike to run correctly or start consistently. I was out riding and there is a shop with a good reputation nearby so I dropped it off to see if he could jet it properly.. I should note at this point stator was replaced, pickup coil, ecu, coil,spark plug,cap,plug wire. New handlebar switch (oem) wiring gone over, replaced any suspect connectors or wiring.. Also all of those items had tested good other then the ecu I could not test.. The new ecu was a new ecu not a new used one.. The new mechanic had the bike for several months and after a few calls he finally got to working on it when he told me the motor was not assembled correctly base gasket was on backward, he claimed the valves were not set right, and a few other things.. Said he would rebuild it but do it "his way" "the right way" . Being I was already far down the rabbit hole I said go for it... The bike was in his shop aprox 1.5 years (yes years!) I got bike back and I am really just back to where I started, The bike will sometimes start effortlessly over and over.. If it flames out or stalls it is difficult or just impossible to get running again... (also sometimes just does not start from cold) Everytime it does not start I immediately pull plug to make sure I have spark.. I was never quite sure if this was a weak spark issue, fuel or both.. I since switched to a coil on plug system and I always have dark blue spark, even when it is not starting.. I'm probably missing quite a bit condensing this story.. For the purposes of troubleshooting we should assume motor is good internaly (does sound good now when it runs) and the problem existed before first rebuild, after first rebuild and after second rebuild. So for the sake of argument lets rule that out.. Let's also assume that wiring, ecu, stator, pickup coil and coil are in good working order as they have been replace, tested and re tested.. Carb was rebuilt by me, ultrasonically cleaned and gone over by shop.. Kill switch was tested and re tested and even unplugged for the purpose of ruling it out.. All grounds have been gone over and or upgraded. (I did not run a ground from sub frame to frame and or motor but seem to get good continuity) and the way that bike is designed I don't think that would matter anyway as long as the chassis to motor grounds are good for kill switch, ecu and coil... So I am turning to you guys for some suggestions as I am near out of options.. Brand new gas tank, petcock and fuel line. Current jetting, fcr mx 39mm carburetor. 148 pilot, ocemn needle, currently 165 main (waiting on a 162 as I read thats the highest you can go with that needle) but this is a recent change bike acted the same with other jetting specs, needle. Float height is set correctly to 9 mm and tested by blowing through it and feeling when it closes. Float needle is new as is the seat and filter.. All other jets are stock sizes, accelerator pump was rebuilt, timed and working properly... No leak jet on this carb, I did install a diaphragm with a bigger rivet and was able to slow down the "squirt" from about 3 seconds as oem design to maybe 2 seconds (1 second shot is recommended).. I did notice some epoxy on edge of flywheel last time I had cover off, could very well be from original manufacturing but I had some hard starting old husqys with the magnet laminating failing issue. I do not see any common issues with the kokusan stators as the sem stators have.. My thought as to next step is potentially buying a new keihin knock off carb (I have had on on my yz for years and it works great) Cheap way to rule out carb problem plus I could get the newer style carb with the more common pilot jets and an external fuel screw and a leak jet. (adjusting fuel screw on this bike is ridiculous for someone with big hands!) Any suggestions to save this old beauty? I have no choice at this point but to get the bike corrected if it takes the rest of my life! I have a yz250f and wr450f to ride so I don't need to be in a hurry with this bike and actually may see more supermoto hours then trail hours..

I recently rebuilt the bottom end on my 2008 yz450f and it took awhile and now that its back together the weather is drastically different from what it was this summer and the bike is very sputtery and hesitant around 1/4 throttle. I went up a size pilot jet from 48-52 and that helped a little but its still pretty sputtery. The issue is happening right before 1/4 throttle and just after the bike will idle along with barely any throttle and as it approaches 1/2 throttle it starts to open up and smooths out. Because I have not yet put an hour on the rebuild I cant go beyond 1/2 throttle yet but its tough to put and hour on it right now as sputtery and hesitant as it is around 1/4 throttle. Its also as if the fuel/air screw has very little effect on the way it idles and runs it doesnt start to change anything until around 3turns out from closed. Currently Altitude 760ft above sea level Temps 40-60°F Main 165 Pilot 52 Fuel/air screw 3-4turns out(anything less has little effect but more pops, anything more has little effect but revs a little slow and idles slightly worse) Bad fuel screw maybe? Needle(factory I believe) 4th clip position from top Starter 72 Leak 55 AP has good strong squirt barely misses hitting the slide. Bike also has full Dr D exhaust and a hot cam. Any help or suggestions are greatly appreciated.

Hi, I already posted about this a few months ago. I wasn't sure what the best option was to upgrade my pretty stock DRZ400sm (only has aftermarket exhaust for now). I'm definitely going to be doing the 3x3 mod in the next few weeks but I'm still hesitating between buying a JD jet kit for the stock Mikuni carb or buying a used fcr39. I have 2 questions the answers of which should help me decide. On the local classified, there is currently a 2002 ktm 400 exc FCR39 for sale for much cheaper than the price of the kit on TT (also I'm in Europe so anything I buy on this website is going to be really expensive to ship my way). Does anyone know if the 2002 exc had FCRMX or the older model? Will it fit the DRZ? If I decided to pull the trigger on a used FCR39 (mx or not), are you guys aware of anyone doing a decent conversion kit? On TT I only see the entire kit including the carb, that I would obviously not need if I got a used one. Thanks!

I've decided to attempt the mid-body gasket replacement on my vintage 2000 slant FCR carb, stock on the DRZ 400 E. If you are like me you have scoured the forums for info on doing this service but found maybe 2 or 3 pictures of a taken apart FCR, dead end threads, and tons of negativity. BUT! Is it really that difficult of a repair to perform correctly? Well I have had my carb on and off at least a dozen times, trying different jets, cleaning, etc. For the last 3 years I've been getting by with the coast enrichener circuit bypassed to at least get enough fuel in the idle circuit to run ok. But it just wasn't working anymore. I could clean the carb out and get it to run for a little while, but after sitting it wouldn't start again. I tried ordering a refurb FCR-MX over a week ago and the guy has gone MIA and nothing shipped. I ordered from keihin-fcr.com. I would advise avoiding... But will update if I hear back and he has a decent reason for the delay. Anyways, it made me seriously look into the "unserviceable" midbody gasket. I mean, you can buy the gasket here: https://www.ebay.com/i/401380298480?chn=ps So today I ripped the carb apart again, but this time to the very last fastener, separating the carb bodies. I even found my smoking gun, in the one picture with the hoop thingy removed you can see the gasket has expanded and spilled into a passageway. This passageway leads directly to the pilot jet, blocking it's flow. Though as you can see every rubber piece inside is completely trashed. Which makes sense, do you really expect these gaskets to last 20 years? Or in this case 18? If you have taken apart your FCR and went, wow that fuel bowl gasket is recked yo! I need a new one! Well you can bet your mid-body gasket looks the same. Really I see no reason I couldn't get this sealed back up with a new gasket and some fuel-proof RTV to replace the epoxy seal around the edge. Why wouldn't it work? Just doesn't make sense to me all the negativity you find toward this repair.... But I haven't finished yet so who knows if it will actually work on the bike. But I think it'll run like new when I'm done. I hope it works out for me and I can inspire some others who would otherwise be forced to buy an 800 dollar carb to do this repair instead. Wish me luck!

Heyo! Let me start by saying hope everyone is keeping safe and healthy right now and thank you in advance for any help. Since i had some free time i decided to go ahead and try the fcr-mx 40 carb mod on my XR650L. Its been desmogged, desnorkled and has a UNI air filter, aside from that everything is stock. It came off a 2002 CRF450R ad was cleaned and rebuilt with a fresh kit by myself. I got the Nos adapter installed on the carb and than installed the carb on the bike. I followed some recommendations for tuning but could never get it to run just right. Just before i took it off i had it running well enough to get my to the gas station but it was still running a little funky. I noticed to increase in power or throttle response and when i would open the throttle i felt a minor bogging. Ok, so that brings me to now. I decided to do the Daves Carb Mod on my original carb and install it on the Xr so i can at least ride while im figuring out the FCR. I followed all the instructions, the only exception is i put a 152 main jet because that it the largest one on hand. when i went to start the bike it was having a bit of trouble, i had to hold the throttle open a little to get it started. Now here is the problem im concerned about. When it started it was puffing white smoke and the exhaust was popping a lot. It almost sounded like a to stroke. This has got my a little confused and that is why i am reaching out now. If you have any help for either of the carbs i would greatly appreciate it. Sorry for writing you a book, hope you liked it. Here is a run own of the bike and carbs: XR650l: -Uni Air Filter -Desmogged -Desnorkled Ridding in Montreal about 600-800 feet above sea level. Fcr-Mx 40mm: CRF450R Needle 5th clip position -48 Pilot -170 Main -All other jets are stock Stock CV Carb: -Cleaned and rebuilt with a fresh kit -Daves mod -55 Pilot -152 Main -Screw 2.5 turns out

I recently bought a 2000 Drz400s and cant get the fcr carb adjusted properly. The bike has 434 big bore kit, fcr39, 3X3 mod, and slip on DG exhaust. Was wondering if anybody else has this set up and what jets they are running or any idea what to fix. Currently the bike keeps breaking up

After several jetting changes, and chasing after an intermittent failing ignition coil. I finally figured out why I couldn't ever eliminate my low end bog off of idle. After watching some YouTube videos I decided to look into A/P timing. Come to find out, the A/P wasn't really squirting anything at all. After several attempts and different positions, I'd come to realize the only possibility was that the diaphragm was installed wrong. Took it out and flipped it over, and viola! Finally had a strong squirt! Cleaned the air filter while I was playing with the carb, so by the time I got the carb figured out and reinstalled and bike reassembled, the filter was dry and ready for oil. All said and done, fired on the second kick, and no more bog. Nice crisp throttle response all the way thru, and just single pop on closing the throttle. I guess this is what happens when you assume the last person inside the carb knew what they were doing. Because I put it back together exactly how I took it apart. Haha

Hey guys, I just joined but I have used this site for many different occasions. But know I have finally ran into an issue that I cant solve with the search feature. I have a 2009 wr450 that I just purchased a month ago with some issues. First ill tell you the list of mods done to it. yz cams r and d powerbowl TPS diconnect Grey wire cut JD jet kit. but i cant tell the needle color and i forgot the clip position. has the up graded AP spring 06yz450 header with a lexx exhaust with the baffle installed. I am having an issue getting the fuel screw dialed in. The only time i can get the bike to change rpm with the fuel screw is with the #42 pilot jet installed. but when i do as I have been instructed (IE adjust the screw in till it stumbles then back out till the best idle has been achieved) The bike seems like it is really lean. I say this because my header temp gets up to 700° and i start developing a nasty engine knock. This does not happen when i go up a size. I have tried #42, #45, and #48 pilot jets. Has anyone ever dealt with this issue before? If so what did you find out? Thanks for the read!

I've fitted an FCR MX 39, RS2 (my god. uncorked, that's loud) and done the 3x3 mod. Turns out I need to reduce the size of my pilot jet - bike still idles with fuel screw fully wound in. Currently I have a 45 fitted - I've got a 42 to try. BUT... I need advice on changing the PJ with the carb still on the bike - I really don't want to take the carb off. The pilot jet is recessed and needs a flat blade screwdriver to remove it (unlike the main jet). Thing is I can't get any of my stubby flat blades in the limited space below the float chamber. If I loosen the hose clips and try to rotate the carb then the throttle wheel fowls the frame and prevents the carb rotating, so that's not an option. Any clues/advice on removing/refitting the PJ? Thanks!

Hey all, I have got some carb trouble. I have been riding around my 2001 xr650r on roadtrips for about a year. Mostly up in northern california in the winter where its cold. With my FCR41 ive always had the issue where if i leave the petcock on, it wont start due to flooding. The bike runs great, just I have to turn off the petcock when doing ANYTHING.. like stopping to piss .. ANYTHING. I was on a recent trip through Arizona and Nevada a few weeks back and noticed that it was running super super hot. It was 115F outside, but the bike hit 250F on the vegas strip. Ive got a TT Vapor on there, so I am monitoring the water off the block. I have engine ice in it and a 1:8 cap. I figured with these two issues, its time to mess around with the carb. I pulled it apart and found that ive got a 160 main jet, 55 pilot jet and an OCEMP jet needle. The Needle clip was on 3/7 (from the top of the needle). So I set the needle clip to 5/7 and adjusted the float a tad leaner (its supposed to be 9mm). I also set the fuel screw to 2 turns out. Put it back together and MAN, the mid range really picked up. It also seemed to run a little cooler (around the 175F range). Problem is that when i roll off the throttle it bogs down to about 900RPM and then dies. If i keep on the gas, it does just fine. additionally, when on hills, it dies when i get to a stop on a hill (san francisco). Thinking that this is the float. Can anyone steer me in the right direction about the bogging and dying on hills when the throttle is off? It did not do this before the adjustment of the needle, float and fuel screw. I read that 55 is pretty rich for a pilot jet on this carb/bike. Seems most people run 45-48 pilot jet. My main is also pretty lean looking at 160 when most seem to be up in the 175-185 range. Thoughts?

I've been trying to work out this low speed jetting issue for a while now and am running into some weird problems. It seems like most of the bikes I see with this mod are running either a 42 or 45 pilot and now I'm sitting at a 55 and still having lean running issues. The bike will cough through the carb at less than 3 turns under 1/4 throttle on fuel screw. Above 3 turns it will run fine off idle but the idle sometimes hangs. As the bike sits it's running 55 pilot, 85 pilot air jet, ELT needle (NCVT equivalent) three clips from the bottom, and 165 main jet. Above 1/4 throttle the bike runs like a champ and pulls hard throughout the rpms/throttle position. With the 55 pilot I can set the fuel screw ~3 turns out and I won't get any cough back through the carb under 1/4 throttle but it has problems with the idle hanging intermittently. Anything above 3 turns out and the idle starts to drop and the bike will stall. I'm around 500 above sea level. Carb has a new vacuum release plate o-ring, completely cleaned out, hot start air ports rtv'ed shut, rd powerbowl 2. Another thing is I bought the carb missing the whole tps sensor (might be an issue) but I tested the open part where it should be by spraying propane at the opening and had no change in idle speed. I've got a 58 pilot on order but it just seems like that's big compared to everyone else. Any advice would be appreciated!

I took the carb apart to inspect why there was a small gas leak and when I took the accelerator pump apart the diaphram was ripped up And pieces of the rubber were in there it wasnt like that two weeks ago what did I do wrong? Was it in upside down or something? Im trying to figure out what is the right way so I dont mess up the new one some one please help is this the order it goes on

I have a 41mm FCR-MX carb off a 2007 CRF450R, installed on my 2001 XR650L. This is the 'updated' FCR design with the larger bore, newer accelerator pump cover/diaphragm and a slightly different needle design. The needle has a little extension at the blunt end, making it impossible for the needle to fall through the slide, and also easier to remove when you want to swap the needle. It has one less clip slots as well due to the tab. Here is a photo comparing the two styles: http://www.pbase.com/jdjetting1/image/64622985 I want to run the NCVT needle, which I currently have but it isn't this 'newer' style. Just a plain ol regular Keihin needle. I'm pretty sure it will work just fine, I just won't have the convenience of pulling the needle out quite so easily. Can anyone confirm that the old needles work fine in the newer FCR? I have it installed now, so it does fit fine and everything, just not sure if the taper and rest of the needle will be lined up where it should be. Thanks!

I’m currently at stock jetting on my 2003 yz250f. I’m rebuilding the top end with a 269cc big bore kit and installing an FMF power core 4 with megabomb exhaust. Current elevation is 700’ above sea level. Where should I start with my jetting? And where can I buy individual jets so that I don’t have to buy an entire assortment? Currently: 178 main 42 pilot needle is 4th Clip from top (stock)