NO more bogging on the FCR

[Colby@C&DRacing]

While we were at the dealer show this weekend I discovered a fix for the FCR carb and the bogging issue we all have been fighting. I spent allot of time at the boyesen booth discussing this problem. Boyesen has a new product out that eliminates this inherant FCR bogg for the MX carbs but they did not know that we use a different FCR carb on our 400ex's. They did not know if this part would work either. After I got home yesterday I did some parts comparison between the aftermarket FCR and the FCR mx and found that the part #'s for the accelerator pump cover on the two carbs is the same.

So what I am saying is, is that we have a bolt on parts that will make the FCR carb perform like it should. This part will be addvertised in the ATV mags some but have already be tested by the dirt bike mags and they gave it a 5 Star rating.

The boyesen QuickShot is available from C&D Racing they retail for $89.95 our normal price will be $80 but we made an advance purchase and will sell the first 15 of them for $70

If you have any questions call us at 402-614-2508

[Colby@C&DRacing]

Stock accelerator pump covers permit only a 60% - 70% fuel charge in the pump chamber. Turn the throttle and air in the chamber is compressed and fuel is delayed. The result: Hesitation or Bog. The Boyesen QuickShot cover completely fills the pump chamber with fuel, and provides instant fuel delivery, eliminating the hesitation and bog. *Fits all 4-Stroke Keihin FCR carburetors *Instant response to throttle movements *Improved low end performance *Reduced hot engine stalling *No modification required - simple bolt-on

[honduh440]

that is great ill get one in a couple weeks

[K_Fulk]

Factory r&d has been selling them for quite a while now...

http://www.mxsouth.com/factoryrd/fac11p-38li.htm

[Colby@C&DRacing]

They are similar but mot the same. I like the boyesen one better they eliminated some other issues.:)

[K_Fulk]

If they can improve on them thats great. I know the r&d ones work awesome. Can't ever be enough competition. :)

What did they improve?

[Aceman]

I don't have an FCR personally but the way I'm understanding it, makes it sound like BS to me. The way I'm reading this is: FCR carbs have a factory flaw in them that requires you to pay 89.95 to fix. That's like saying there is a recall on your cars' seatbelts because they don't hold up in a crash. But if you want it fixed you have to pay for it. What I'm getting at is, why don't they come from the factory with this new and improved part? Or at least offer a free upgrade if you send in your old carb?

[tdsongster]

Is this for the FCR carb that is on my 400EX?

[K_Fulk]

They work on all fcr's.

[NacsMXer]

That's pretty sweet, I might order one soon. Now im wondering which of the two companies makes the better accelerator pump plate. :confused:
My quad is pretty fast, but has always had that hesitation if you pinned it since I put the FCR on there. To me it seems like a necessary fix.

[cals400ex]

Originally posted by Aceman
I don't have an FCR personally but the way I'm understanding it, makes it sound like BS to me. The way I'm reading this is: FCR carbs have a factory flaw in them that requires you to pay 89.95 to fix. That's like saying there is a recall on your cars' seatbelts because they don't hold up in a crash. But if you want it fixed you have to pay for it. What I'm getting at is, why don't they come from the factory with this new and improved part? Or at least offer a free upgrade if you send in your old carb?


i wouldn't call it a flaw. it is like any other motor part. you do some modifications, you get more power. also, we need to remember the fcr carbs were not designed in the first place for a 400ex. they have been converted in such a way that they do work pretty well though. there is nothing broke on the fcr's that are out, hence no reason for a recall. i see what your saying though, that is a pretty penny for a little piece of metal.

[cals400ex]

would you think this could improve the fcr40mm carbs? this is what i am currently running. i know the first year these were on the 450 dirtbikes, they had a different accelerator pump and assembly. i bought my carb used and he told me to buy an 02 and newer (i believe it was 02 and newer) assembly and the bike would run better. well i bought this and put it in before i ever ran the other one. just kind of curious if you think it will help on this carb too.

[Colby@C&DRacing]

The improvement comes from eliminating the air inthe pump chamber. If there is room for air int he chamber under the diaphram, the air has to be compressed far enough to build the required pressure to push the fuel throught he nozzle. this only happen with a large applicaton of the throttle and it is delayed( This is were the bogg coms from). This also causes a weak stream of fuel not a hard dirrect spray. Another problem with the fcr is that is you are riding just about idle to around half the pump only dribbles fuel in the carb at best, with the quick shot it will shoot an instint burst of fuel even when you only accuate the throttle a slight bit.

This will work on any FCR carb and will provide quicker throttle responce and eliminate any bogging.

[cals400ex]

i only get a miss when i quickly hit the throttle. it seems after the spray quits, it runs awesome. i have my squirt down to less than a second and it still does this. i think it would run best if i eliminated the accelerator pump. i only have problems at lower rpms though. it is most noticable when punching it quick at slow speeds when trying to ride a wheelie.

[Aceman]

Originally posted by cals400ex
i wouldn't call it a flaw. it is like any other motor part. you do some modifications, you get more power. also, we need to remember the fcr carbs were not designed in the first place for a 400ex. they have been converted in such a way that they do work pretty well though. there is nothing broke on the fcr's that are out, hence no reason for a recall. i see what your saying though, that is a pretty penny for a little piece of metal.


So what I am saying is, is that we have a bolt on parts that will make the FCR carb perform like it should.

Looking through Sudco's site on FCR carbs they have a specific carb listed for the 400ex and none of the other motorcycles/atvs share the same part number with it. This leads me to believe something is specific about the carb even though it is probably something minor like how the throttle cable is connected, etc. Keihin's site says they are produced for most popular motorcycles and I would assume atv's are included in that. It seems to me FCR's were developed to be a universal aftermarket carburator to increase performance. So I don't understand how you could say they weren't intended for a 400ex when they are universal? Sparks racing say in their description "acceleration without flat spots," I would call bogging a flat spot. Why does a 450-500 dollar carburator need another $90 fix to work properly? The only excuse I could think of is that this problem is 400ex specific and doesn't happen on other motorcycles/atv's with the same carb. But then why would Sparks say there is no flat spots with this carb on 400ex's when there clearly is more than just a few people with this problem. Unless they have a way of tuning the carb to get around this hesitation in throttle response? Or is it just a lack of r&d on Keihin's part not realizing the problem with the accelerator pump cover?

[K_Fulk]

Before I had my r&d plate. If i was at a race before the start I would raise my idle up enough to get rid of the bog. Then after the race i would turn it back down. Thats about the only other way to get rid of it for a 400ex that I found.

[cals400ex]

Originally posted by Aceman
Looking through Sudco's site on FCR carbs they have a specific carb listed for the 400ex and none of the other motorcycles/atvs share the same part number with it. This leads me to believe something is specific about the carb even though it is probably something minor like how the throttle cable is connected, etc. Keihin's site says they are produced for most popular motorcycles and I would assume atv's are included in that. It seems to me FCR's were developed to be a universal aftermarket carburator to increase performance. So I don't understand how you could say they weren't intended for a 400ex when they are universal? Sparks racing say in their description "acceleration without flat spots," I would call bogging a flat spot. Why does a 450-500 dollar carburator need another $90 fix to work properly? The only excuse I could think of is that this problem is 400ex specific and doesn't happen on other motorcycles/atv's with the same carb. But then why would Sparks say there is no flat spots with this carb on 400ex's when there clearly is more than just a few people with this problem. Unless they have a way of tuning the carb to get around this hesitation in throttle response? Or is it just a lack of r&d on Keihin's part not realizing the problem with the accelerator pump cover?


i didnt' realize they made a different one for the 400ex. i hear people all the time swapping back and forth from a z400/kfx to a 400ex. the individual i bought mine from had a Z so i know mine wasn't made directly for a 400ex either. i do run an aftermarket throttle cable though.


what i mean when i say they weren't intended for the 400ex is this:

their accelerator pump squirts for several seconds. this is just way too long for the 400ex motor. heck, i currently run a fcr 40mm carb that comes on crf 450 dirtbikes which has way more power than the 400ex and the carb squirt is less than one second for that motor. i modded my fcr 39 so the squirt was a much shorter duration, less than one second actually. this produced much much better throttle response and the bog wasn't there that there previously was. i actually removed the accelerator pump once to see how it would run. it ran awesome until i would quickly snap the throttle, then it would hesitate.


sparks realizes these carbs aren't perfect for the 400ex. they know there is a hesitation and they admitted to it when i called. yes, sparks uses a different needle than the stock fcr needle and i had that one. actually, i sold it to kfulk before i even used it. however, my buddy has one and his bike runs pretty good. what irritates him is his bike studders on full throttle wheelies where the stock carbs we didn't have problems with. i don't know. i don't think this piece of metal will fix everyones problem. i never noticed a flat spot with this carb. mine simply hesitated on a quick snap of the throttle, like my fcr 40 does. i think i may need to try a different needle though. i may do that tomorrow because have a few sitting here at my house. i may get that plate to try it out, who knows.

[dork]

the fcr's were originally developed for racing superbikes, so they were used in fours and thats why the accelerator pump squirted so long, to feed the other 3 carbs. only one carb had the pump assembly hooked up, so it needed some time to feed the other 3. go on sudco's site and look at the parts diagram of the fcr horizontal and downdraft carbs, you can see it.

the fcr's sold by the aftermarket don't have the auxillary bowl vent on them like mx versions on the yzfs and crfs, or the baffle around the main jet, so that may be where the bogging/stuttering is from.

you have to be careful when adjusting the spray timing, if its too early it will hit the slide before it raises enough, that was part of the problem on the yz426 when they put the fcr2 on it in 2000.

[JDiablo]

hey colby Pm me a price with this and a FCR carb for a 400ex that has a stage two hotcam lighten freewheel and the head is ported,running a open airbox,HMF full system and K&N filter what size will be decent? 39?

[KFX]

Im running a fcr39 off of a yz400f dirtbike. When the motor was stock (slip on and pro flo) it would bog on the low end. Because the carb was to much for it. Now that the motor is built with a 440 cams etc. It is much better.

[EPDP99]

I have yet to do the mod to change they spray time length. What is the best was and will the accellerator pump cover help at all with this? I have done a search but it seems im not really happy with taking a rc wheel clamp or whatever and clamping it down on the shatft. It seems there is a better way.

[wilkin250r]

Bringing up an old thread because I came across this just the other day.

http://www.thumpertalk.com/forum/forumdisplay.php?f=104

[400exredrider]

anyone know if this is fixed in the 2002 CRF 450s carb its the FCR 40mm and i havent really noticed and hesitation,, i love beinge able to just give the throttle a few blips then crankin the starter and lettin it rip,, that was until i dropped a valve

[dads400ex]

Going to bring this back up to ask if anybody has used this cover yet? If so how did it do, did it fix the bogging? Need to take care of the bog on my sons Z, it has the 40mm FCR on it and we can't get rid of the the off idle bog.

Thanks

[2muchquad]

i personallyhave had good results running a shorter duration squirt,i also have mine on a yzf mx bike too,i hear the quad ones may be different though:)

[Ex'r Marlin]

I had the hesitation, until I bought the Boyesen piece from C&D Racing.

Very simple instal, that resolved the hesitation I had.

Before I installed the Boyesen, I had my atv dyno'd several times with various adjustments to get the optimum performance, hoping it would reduce the hesitation at the same time.

When I threw the throttle to the wide open position as fast as I could from an idle, there was still a hesitation to the point that the engine would shut down if I did not let up on the throttle.

I installed the Boyesen without the washer, and have been a happier EX rider since! :)

Thank you Colby! (C&D Racing)

Added note: I had my idle adjustment set high before I installed the Boyesen.

[skitstvdotcom]

Originally posted by Ex'r Marlin
I had the hesitation, until I bought the Boyesen piece from C&D Racing.

Very simple instal, that resolved the hesitation I had.

Before I installed the Boyesen, I had my atv dyno'd several times with various adjustments to get the optimum performance, hoping it would reduce the hesitation at the same time.

When I threw the throttle to the wide open position as fast as I could from an idle, there was still a hesitation to the point that the engine would shut down if I did not let up on the throttle.

I installed the Boyesen without the washer, and have been a happier EX rider since! :)

Thank you Colby! (C&D Racing)

Added note: I had my idle adjustment set high before I installed the Boyesen.

that is what happens to my kfx with the fcr39 on it... slam the throttle at idle and it bogs and dies.. I just wish this part was cheaper than $70-80...

[Juggalo]

im sorry if this is a stupid question but does this peice reduce the squirt duration or does it help in some other way to get rid of the bog?

[wilkin250r]

Originally posted by Juggalo
im sorry if this is a stupid question but does this peice reduce the squirt duration or does it help in some other way to get rid of the bog?

I'm not exactly sure, but from the beginning ofthe thread, I don't think the squirt duration was the problem, but rather the squirt timing. There was air trapped inside the accelerator pump diaphram, so when you stabbed the throttle, the air would compress, and THEN it would squirt, basically causing a delay. Unfortunately, that delay was enough to cause the engine to bog down.

The boyesen cover eliminates the trapped air, and thus eliminates the delay.

[400exredrider]

makes sense,,, i didnt notice it much on the fcr40mm

[Juggalo]

Originally posted by wilkin250r
I'm not exactly sure, but from the beginning ofthe thread, I don't think the squirt duration was the problem, but rather the squirt timing. There was air trapped inside the accelerator pump diaphram, so when you stabbed the throttle, the air would compress, and THEN it would squirt, basically causing a delay. Unfortunately, that delay was enough to cause the engine to bog down.

The boyesen cover eliminates the trapped air, and thus eliminates the delay.

ahh ok! thank you wilkin i finally understand now

[kilabeez0]

Originally posted by Aceman
I don't have an FCR personally but the way I'm understanding it, makes it sound like BS to me. The way I'm reading this is: FCR carbs have a factory flaw in them that requires you to pay 89.95 to fix. That's like saying there is a recall on your cars' seatbelts because they don't hold up in a crash. But if you want it fixed you have to pay for it. What I'm getting at is, why don't they come from the factory with this new and improved part? Or at least offer a free upgrade if you send in your old carb?

because how would these site sponsors make any money?:devil:

[shawn1103]

i bought the boyesen quickshot for my 39 fcr carb. and it didnt help out the bog at all. it still has the off idle bog and hesitation. i dont know what to do.

[quadmxracer]

I still have the same problem as you w/the off idle bog even after I bought the plate.

[tdsongster]

I bought one for my FCR 39 and had C&D install it and jet it. It took him a couple of tries, but now it runs really hard. The only thing is now i do not give it any throttle trying to start the thing of it will flood out bad. That was my fault though, just getting used to the thing. That and all of my other mods that I just had done. It is a totally different machine.

[TORO1968]

I still have the off-idle bog as well. Once there is a tiny bit of load on the engine though, there is no bog problem.

I'm happy w/the gains I got from the Quickshot, however, I wish the off-idle problem was taken care of as well. Guess I might have to put the collar on the accel pump rod and adjust the squirt timing...

[NacsMXer]

Originally posted by TORO1968
I still have the off-idle bog as well. Once there is a tiny bit of load on the engine though, there is no bog problem.

I'm happy w/the gains I got from the Quickshot, however, I wish the off-idle problem was taken care of as well. Guess I might have to put the collar on the accel pump rod and adjust the squirt timing...

I agree, I've just gotten used to rolling into the throttle rather than punching it. When I was asking Curtis Sparks on the phone about the hesitation problem, he said you should be riding it like a 4-stroke (rolling into the throttle) instead of "chopping" the throttle like on a 2-stroke bike.

Good info on the Quickshot guys, i've been considering this mod for my FCR 39 that has some hesitation. The ad made it sound like it completely cured the hesitation, but what you guys are saying that it didn't cure it at all? So overall, did the Quickshot help any with the quad's performance, and if so, how did it help? Thanks :)