It's less common nowadays, but it used to be. There are two types of FCR carbs. The older one referred as slant or gen 1 and the newer, the ΜΧ. These two have different slide plate. The older had an L plate, while the MX had an M (as shown in your video). Many people who didn't know replaced the L in the slant with the M from the MX. It kinda fits but if you know you'll notice that is not sealing properly. So they had strange idle problems and was looking the wrong direction (the jetting).
I had the original slant carb on my bike. I ended up switching it to a 2006 one and swapping throttle cables. Had to delete the old hot start system but I can stress enough how much better the newer gen carb is soley for the fact that you can tune the accelerator pump on it. The slant having all the pump components external also caused potential issues as well
Hello, I have a 2002 KTM 400, still rides not bad at all. The main problem is hard starting. After it warms up, there is no problem anymore and it drives well. After trying and cleaning, I discovered that if you disconnect the TPS sensor, it starts really easily. Can you travel without it? Maybe direction or something else? Thanks, Eyal
Any idea on why would the accelerator pump on FCR Carb squirts great no bogs when stabbing the throttle when engine and carb are cold. And once the engine warms up good, and carb gets hot, it won't squrt. Cleaned the carb many times. changed gaskets and origns, new accelerator pump diaphragm, boyesen quick shot 3 and o-ring mod. I've been figting this thing for a while, with no luck. Once the carb cools down a bit it starts squiring again. Thank you.
Interesting, so you've tested the AP squirt while everything is still hot? (Just curious, because it's super easy to remove the airbox or carb, depending on which bike you have). I actually made this video on the FCR AP not squirting because I was having that issue at all times: th-cam.com/video/Q4chsxhGXz4/w-d-xo.html Let us know what you find out.
@@MotocrossHideout yeah when everything is still cool it squirts no bogs when stabbing the throttle . But once the engine and crab warm up good , it seems like it’s sucking air from somewhere instead of fuel. I took the carb apart bunch of times. I use to have it all the time , but once I replaced all gaskets and stuff inside not only does it when it gets hot .
Hey bro, ihave dismounted mine and put to work after a lot of days, after 1 months my bike dont start again, i have see that the fuel dont go in the carb!!! Why?? It go trough the line but dont go trough the yellow attachment of carb, the breather was new….
So are you saying that the fuel goes through the hose from the gas tank but it doesn't flow into the carb? The fuel inlet/elbow on this carb can be removed with the screw. You could see if that passage is clogged. Otherwise the float needle and seat might be gummed up/sticking shut, not allowing fuel to flow into the float bowl.
Im not sure if anyones gonna see this but i need help with my 2005 ttr 250. It runs fine at idle and it dont have a problem goin from zero throttle to full throttle but if i try to cruise or keep the throttle in one position its cuts out rlly bad. But it dont try to die its basically unridable in this condition. Ive put a new carb on but its still doing the same thing. It smokes too but cant tell if its white or blue
![4 Stroke Hanging or Inconsistent Idle Fix [7 Common Problems]](http://i.ytimg.com/vi/o2X-nPTS5pU/mqdefault.jpg)
![4 Stroke Hanging or Inconsistent Idle Fix [7 Common Problems]](/img/tr.png)
Which common problem have YOU seen on a Keihin FCR MX carburetor?
It's less common nowadays, but it used to be. There are two types of FCR carbs. The older one referred as slant or gen 1 and the newer, the ΜΧ. These two have different slide plate. The older had an L plate, while the MX had an M (as shown in your video). Many people who didn't know replaced the L in the slant with the M from the MX. It kinda fits but if you know you'll notice that is not sealing properly. So they had strange idle problems and was looking the wrong direction (the jetting).
Thanks for sharing that tip! I was aware of the earlier slant FCR carb, but I didn't know about the different slides/seals.
I had the original slant carb on my bike. I ended up switching it to a 2006 one and swapping throttle cables. Had to delete the old hot start system but I can stress enough how much better the newer gen carb is soley for the fact that you can tune the accelerator pump on it. The slant having all the pump components external also caused potential issues as well
Hello, I have a 2002 KTM 400, still rides not bad at all. The main problem is hard starting. After it warms up, there is no problem anymore and it drives well. After trying and cleaning, I discovered that if you disconnect the TPS sensor, it starts really easily. Can you travel without it? Maybe direction or something else? Thanks, Eyal
I believe you can leave it disconnected, but I'd do some research first. Perhaps the TPS came loose and got out of adjustment?
Any idea on why would the accelerator pump on FCR Carb squirts great no bogs when stabbing the throttle when engine and carb are cold. And once the engine warms up good, and carb gets hot, it won't squrt. Cleaned the carb many times. changed gaskets and origns, new accelerator pump diaphragm, boyesen quick shot 3 and o-ring mod. I've been figting this thing for a while, with no luck. Once the carb cools down a bit it starts squiring again. Thank you.
Interesting, so you've tested the AP squirt while everything is still hot? (Just curious, because it's super easy to remove the airbox or carb, depending on which bike you have).
I actually made this video on the FCR AP not squirting because I was having that issue at all times: th-cam.com/video/Q4chsxhGXz4/w-d-xo.html
Let us know what you find out.
@@MotocrossHideout yeah when everything is still cool it squirts no bogs when stabbing the throttle . But once the engine and crab warm up good , it seems like it’s sucking air from somewhere instead of fuel. I took the carb apart bunch of times. I use to have it all the time , but once I replaced all gaskets and stuff inside not only does it when it gets hot .
@@MotocrossHideout
Cold engine and carb. Working great.
th-cam.com/users/shortsceW83ksKpX4?si=SR2AeXi-MRjJmFfK
@@MotocrossHideout
After few runs around the block to get it very hot.
th-cam.com/users/shortsol28okfIKxw?si=giq_AEzMY4Vgpmap
Hey bro, ihave dismounted mine and put to work after a lot of days, after 1 months my bike dont start again, i have see that the fuel dont go in the carb!!! Why?? It go trough the line but dont go trough the yellow attachment of carb, the breather was new….
For yellow attachment i mean the metal thing that you touch on the first second of the video
So are you saying that the fuel goes through the hose from the gas tank but it doesn't flow into the carb?
The fuel inlet/elbow on this carb can be removed with the screw. You could see if that passage is clogged.
Otherwise the float needle and seat might be gummed up/sticking shut, not allowing fuel to flow into the float bowl.
@ i understand later i try to unclog with compressed air thank you
Im not sure if anyones gonna see this but i need help with my 2005 ttr 250. It runs fine at idle and it dont have a problem goin from zero throttle to full throttle but if i try to cruise or keep the throttle in one position its cuts out rlly bad. But it dont try to die its basically unridable in this condition. Ive put a new carb on but its still doing the same thing. It smokes too but cant tell if its white or blue
If it's smoking then it probably needs the top end rebuilt. Piston and rings, possibly the cylinder if it's out of spec.