FCR accelerator pump

[K_Fulk]

My fcr has a bog if you hammer it wide open, if you roll on the throttle its perfect.
Anyways, i took the ap cover off on the bottom and took the black was her out and noticed it had mud and crud in it. Beacuse the seal had creeped down on the outside.

MY questions

Do you accelerator pumps open quick when you hammer the throttle? Mine moves a little at first and then slowly lets more gas out if i keep it pinned.

If i put a lighter spring on the bottom would it help it open easier?

[K_Fulk]

No one knows about the accelereator pumps?

[Texan32]

i'm not an expert, but i thought the whole purpose of an accelerator pump was to assist with blipping the throttle. When the motor is just idling, there isn't very much vacuum being created. As the RPM's go up, so does the vacuum preasure. So, the pump is supposed to create a little artificial vacuum until the engine can do it itself

[K_Fulk]

Thats why my quad is bogging. The carb opens up to fast and isnt getting enough fuel to keep it running beacuse it opens to fast. I need a way to get it to put more fuel through it.

[thomas]

Make sure you run a big enough pilot jet, I ran a #60, got more bottom end and no more flat spot. Also air screw shoud be 1.5 turns out.
Also, do what they call a BK mod with the AP.
At the bottom you see a small fork which hols the plastic part that pushes the plunger. Got that so far? Now take your carb off and time the duration of the squirt., about 3 seconds, right?
Now, by pushing together the little fork you can reduce the squirt time to about 1- 1.5 sec. This will give you a snappier response, more power and less fuel wasted.
Have fun , the FCR carbs are great to play with!!

[K_Fulk]

Is the fork above or below the plastic part in the carb?

[thomas]

Just to the left, outside the carb!!!

[K_Fulk]

Ok , i got it now but my accelerator pump thing only moves about an 1/8 of an inch.

[K_Fulk]

If i give it full throttle the ap linkage doesnt move to where the throttle linkage is.

[thomas]

Take the carb off and check the squirt time!! If that falls in between 1- 1.5 sec great, now take it for a spin, make sure the engine is warmed up!!

[K_Fulk]

I went riding today, clutch wasnt disengaging all the way and fixed that. After that it worked perfect. Last night i took out the accelerator pump plunger and cleaned it up i think that helped too.

you guys recomend the fcr carb over the stocker for a 416?

[K_Fulk]

Heck yeah.

[Bad Habit]

Originally posted by freeride132
you guys recomend the fcr carb over the stocker for a 416?

ABSOLUTELY

how much are they

[Dave400ex]

$450 from Sparks, but check with C&D.

[jgfarmsracer]

Originally posted by K_Fulk
Thats why my quad is bogging. The carb opens up to fast and isnt getting enough fuel to keep it running beacuse it opens to fast. I need a way to get it to put more fuel through it.

the bogging is the pump puttin to much gas in the motor and acttually to the point of flooding it out, not bogging that's what the pump is for that quick supurt of gas to get that snap

[robby26wi]

They are 356 for the newest version at service Honda....Its the fcr40mm....Great carb...I love mine

[BadA$$440]

Originally posted by K_Fulk
Heck yeah.

Mine FCR runs great low t mid but as soon as it hits top it pops and misses bad. I ave a 52 pilot, 182 main, and third clip down on needle

[Colby@C&DRacing]

Originally posted by Bad*****440
Mine FCR runs great low t mid but as soon as it hits top it pops and misses bad. I ave a 52 pilot, 182 main, and third clip down on needle

You need to put your needle in the middle clip and put a smaller main jet in that carb it is too rich.

As far as the bogging it is caused by a missed adjusted fuel screw. The pump help to keep the carb from leaning out when you punk the gas but if you adjust the fuel screww 99 time out of 100 that fixs the bog on the fcr carb.

[BadA$$440]

what main you reccomend.......170? 175?

[robby26wi]

what carb is it? 39,40, or 41?

[BadA$$440]

39mm

[robby26wi]

o ok...That one jets differently then my 40mm so i wouldnt have a clue on that one..

[Bad Habit]

Originally posted by Bad*****440
what main you reccomend.......170? 175?

Mines a 165 but i think it's a bit on the lean side. I think 170 or 175 would be perfect.

[BadA$$440]

ok, do you guys run aftermarket CDI's?

I just took the carb off, cleaned it, made sure the acc. pump was working smoothly. I noticed it was a 50 pilot i had in it ( bought the carb used) . Clip on needle was exactly in the middle ( 4th clip down i believe) and i went from a 182 to a 175 main jet and it kept breakin up on top. Like i said before low - mid it ran great but as soon as i got in the high rpms it starts to pop and break up like a mofo......could this be the stock rev limiter cutting it out? It does feel like with the FCR it revs out quicker, plus i got small gearing ( 14/38 with 18'' tires.

and also..when you take the float bowl off, u see the main jet, then to the right you see the pilot and in front of the main there is a screw.....what does it do and should i check it ( could this be the problem?)

[skemp]

That's the fuel screw. Try a 165 main. I run that on my 416 with all the fixuns and it is perfect. I believe I have the screw out 2 turns with a 52 pilot. See where the screw is at, it can effect the entire rev range.

[Hoodeye3]

I agree with Skemp sounds like your still fat on your main jet , Ive worked mine down to a 165 and run a #50 pilot and EMT needle and mines dialed nicely now.

[BadA$$440]

ok, i know its definatley the carb and not the CDI b/c i put my stock carb back on with a 165 main and it ran fine......so i will try that 165 in the FCR and see how it does.

dont buy a rev box, the ex only makes the most power between 6-8000 rpm you not gaining anything by getting more revs except your putting more stress on your motor imo

[jgfarmsracer]

Originally posted by Yellow416ex
Mines a 165 but i think it's a bit on the lean side. I think 170 or 175 would be perfect.

i run a 180 on a 440 with a port job

[skemp]

Originally posted by freeride132
dont buy a rev box, the ex only makes the most power between 6-8000 rpm you not gaining anything by getting more revs except your putting more stress on your motor imo

Yes, but with an aggressive cam, the power curve can be moved upward in the rev range, where an aftermarket CDI can be utilized. I run a stock CDI by the way, because I don't feel the need to rev mine over the existing limit. Just FYI :)

[Dave400ex]

Will I feel a big difference running my FCR with a stock motor? I haven't put it on yet. Also have you guys hit the rev limiter more with the carb since it revs quicker or is that not really a problem?

[robby26wi]

Its usually 5-6 horse and thats like a pipe and header....did u feel that?

[K_Fulk]

Originally posted by Dave400ex
Will I feel a big difference running my FCR with a stock motor? I haven't put it on yet. Also have you guys hit the rev limiter more with the carb since it revs quicker or is that not really a problem?
I didn't notice it i was always bouncing off the rev limiter anyways. You will still be a diffrence but there will be more of one when you get some motor work done.


Well i ordered a fuel screw and a needle from c&d today hopefully that will help it out. If not ill play with the jets then see if i can mess with the accelerator pump more.

[Dave400ex]

So there is really no problem with the limiter then?

[K_Fulk]

Nothing quick shifting can't fix.:cool:

[Dave400ex]

Yeah I usually short shift anyways, but just wondered. Last question is, you guys that live in the real cold areas, do you have any problems with starting, and if or if not how do you go about starting?

[K_Fulk]

When its cold i raise the needle and use ether if i have too , to get it started.

[Dave400ex]

I want to stay away from ether. I heard to just pump the throttle, but on average how many times?

[K_Fulk]

I hit it 4 or 5 times start it then it stalls. Do that cycle 2 or 3 times. More in the winter.

[skemp]

I haven't had my FCR in very cold weather yet, but so far this summer, all it takes is a tap of the start button, and it's purring. I could never get it to start this easily with my stock carb simply due to the flow characteristics of the FCR.

[QuadMatt]

Back to the acc. pump......


So, my acc. pump is moving very slowly when the throttle is pinned. I took it apart and found dirt that had made its way down the plunger shaft. I cleaned and reassembled it. (I may have made a mistake by putting some grease on the top side of the plunger) ANyway, the pump still moves very slowly.

As I understand it, the plunger is "pushed" via a spring. Meaning it is not mechanically actuated by the motion of the throttle linkage.

The fork that is in the linakge appears to adjust the starting point of the plunger stroke thus affecting the volume of the "shot".

Going back to my car days, i recall that Holleys have changeable acc. pump jets that affect the duration of the shot.

With all that said, I just want to know how this thing is supposed to work. How is it adjusted?

Thanks
Matt

[donsimpson12]

This has been my problem as well. The timing adjuster moves that accel pump cam away fro the thottle plate. This is a bad design. You can't adjust too much in either direction.

I've been reading posts on dozen's of forums and I'm starting to believe that most peopelthat are working on these are partially correcting the problem by jetting to such a rich condition that they compensate for the pump timing.

This is what I've doen for the short run until I can really solve the carb's issue. Put a zip-tie around the fork and the black accel cam. This forces the plunger to go down when you blip the throttle. Now you will be getting a fuel squirt each time you pin the throttle as well. this means that you'll go to a slightly rich condition at WOT. This isn't a real problem because your now hitting the rev limited quicker because the accel pump is doing it's thing now.

When you try this, better hang on tight. the power increase is increadable. Suggestion would also be to move the jets down a number or two to compensate for the accel pump.

I believe the real fix is a stornger spring on top and a weaker spring under the diaphragm..

I hope this sheds some real light on the issue.

Take Care
Don