I have THE BOG!

[15round]

I have an 06 450 and on my third ride out (2 to 3 hours each time) I noticed the bog some people experience.When in 2nd gear at low revs I crack the throttle and there is a hesitation.I really noticed it in 3rd.If the revs are high I dont feel it.Is this common on an 06?I wonder why I did not feel it on my first to outings.Maybe I was not riding as aggresivly.

[wanta450]

i get that on my 05 too

[Pappy]

Boyseen Powershot is supposed to do the trick on the fcr. I am getting ready to try one on my YFZ.

[wckedclownz69]

is tht just on 06s??? my 05 does tht...will the boyseen work for an 05?

[bpimpdaddy21]

Originally posted by Pappy
Boyseen Powershot is supposed to do the trick on the fcr. I am getting ready to try one on my YFZ.

From what I have heard the quickshot helps a little, but it is actually that the accelerator pump is out of adjustment. I have talked to several people that have had this and the accelerator pump adjustment fixed the bog. I think the HRC kit says to turn it out 1 1/4" turns.

Someone else chime in here, but I am 99% sure that this would be the cause of the bog.....

Search google for FCR bog or FCR accelerator pump for more info.

[roundsy]

yea ive experienced the same thing, i ve read to add a 55 leak jet and it does te same thing as the boyesen accelerator but i have yet to try either...im going to try the jet before the accelerator... few dollars vs $85

[r450eater]

i have the second gear bog too but any higher its fine

[eagertorace]

try the 55 leak jet first and try that
if that doesn't help then you will have to adjust the pump settings and get the hrc needle, good luck

[roundsy]

quick question...does the HRC kit solve the problem completely, help abit, or does it just make it worse?

thanks

[STR330R]

I think it depends on each quad.. Hrc didn't really help my bog any.

[cals400ex]

the boyseen will not work with the 05

it works with fcr carbs

[Lonestar_R]

I'm gonna try the 55 leak jet and a 48 pilot and a crf needle and the accelarator pump adjustment then the quick shot...if I can get rid of the bog without the quickshot I saved myself 80 bucks.....

[Lonestar_R]

oh and HMF's forum on their website says to turn the accelerator pump adjustment clockwise 1/4 of a turn

[STR330R]

is that a 1/4 turn with the hrc kit or without

[Lonestar_R]

without...it states the HMF needle, quickshot and a 40 or 50 leak jet.....with a 1/4 turn clockwise......its on their forum...

[Jonas]

Your likely turning the throttle faster than the motor will even be able to produce power from. Your motor will never rev as fast as you can snap the throttle. How about if you roll the throttle more smoothly, will that work for you??? I have never noticed a hesitation will riding. I feel that it has to do with the way I turn the throttle while riding.

[LoneRacer]

I Had the same problem and i fixed it for about $25.00 or so.

I used a 55 main jet.

Installed a 45 slow jet.

Bought a HMF neelde and raised it 1 clip "make it richer"

I run a stock pipe with lid.


No bog!

It just needs a tweek!

I love the quad! There is plenty of combos that will work for you here!

PS the HRC kit works also!

Good luck and ave fun...:D

[GIXXER1KR]

i have the ITCH and the CLAPP!LOL!!!!!!!

[chad502ex]

most bogs are from the initial LEAN condition the engine sees when the throttle is snapped open WOT. The accelerator pump is suppose to help cure this. Increasing the compression ratio of a piston or increasing the porting efficiency will make the bog more dramatic.

DECREASE the accelerator leak down jet to 35 (on fcr's). This will cause a longer squirt of fuel into the engine because a smaller jet prevents the AP circuit from pushing fuel backward into the float bowl.

[Lonestar_R]

What is the stock Leak Jet on an FCR......I heard a 70.....that is for the Honda 450R....

[chad502ex]

Originally posted by Lonestar_R
What is the stock Leak Jet on an FCR......I heard a 70.....that is for the Honda 450R....

the OEM accelerator pump leak jet is 55.

SUDCO.com has a breakdown of the leak jets for the carbs to illustrate its location. Basically the float bowl of the fcr is removed and the leak jet is unscrewed from the bottom inside of the bowl.

the leak jet costs $5 each. A Boysen QS does the opposite from what is needed to cure the LEAN bog. A boysen QS costs $80 and does nothing to cure the lean condition on stabbed WOT.

[bpimpdaddy21]

OK, so I got my FCR on today, and I have the bog too. When I stab the throttle WOT, it falls flat on its face and will stall. How do I tell if it is a lean bog or a rich bog, that is one thing I have trouble with. Other than that, the FCR feels really strong when I roll on the throttle.

BTW, I have 55 leak, 168 main, 45 pilot, ncyq needle 4th clip, rossier short can, K&n, HRC cam, and 06 crf fcr. Thanks!

[chad502ex]

Originally posted by bpimpdaddy21
OK, so I got my FCR on today, and I have the bog too. When I stab the throttle WOT, it falls flat on its face and will stall. How do I tell if it is a lean bog or a rich bog, that is one thing I have trouble with. Other than that, the FCR feels really strong when I roll on the throttle.

BTW, I have 55 leak, 168 main, 45 pilot, ncyq needle 4th clip, rossier short can, K&n, HRC cam, and 06 crf fcr. Thanks!

I would almost bet that your bog is a LEAN bog as i described.

Just send me your carb to get taper bored, and your head to port and all will be good.

:D

[bpimpdaddy21]

Well, I didnt see a cost in there, so if its for free, SURE! haha, anyway, I am going to adjust the A/P tomorrow, prolly hitting the slide would be my bet.

But how do you tell the difference? Is the lean bog more apparant, whereas the rich bog is more of a sputter?

[chad502ex]

Originally posted by bpimpdaddy21
Well, I didnt see a cost in there, so if its for free, SURE! haha, anyway, I am going to adjust the A/P tomorrow, prolly hitting the slide would be my bet.

But how do you tell the difference? Is the lean bog more apparant, whereas the rich bog is more of a sputter?

I thought we talked about taper boring costs,...

anyway, great question. very tough to tell on low end. on top end its easier to tell rich because it'll studder. But trust me, that FCR BOG you have is due to the A/F ratio instantly going to the roof on WOT stab.

Look at my dyno pull: the initial start of the test is where the dyno operator stabbed the throttle which cause the carb wide open bore while the engine is pulling vaccuum. Instantly, the A/F goes mostly air and the accelerator pump cant provide enough fuel to bring down the ratio in time. This is what causes the high MOMENTARY Lean condition.

[bpimpdaddy21]

Awesome, that graph is a very good visual to demonstrate this, and helps quite a bit. I know what you mean on the top end, as that is easy to tell if it is a rich or lean condition, at least I think.


Originally posted by chad502ex
I thought we talked about taper boring costs,...

Yeah, we did, but I figured it was worth a shot, haha!

[Lonestar_R]

So Chad do you have to change the squirt time or not....or does the smaller leak jet take care of it.....Like HMF's website says to turn the AP Adjustment a 1/4 of a turn clockwise, does this still need to be done or not, they also say that it has a 70 leak jet....thanks Chad for all the insight.....I'm glad someone knows how to explain the condition and how to solve it......

[bpimpdaddy21]

Originally posted by chad502ex
the initial start of the test is where the dyno operator stabbed the throttle which cause the carb wide open bore while the engine is pulling vaccuum. Instantly, the A/F goes mostly air and the accelerator pump cant provide enough fuel to bring down the ratio in time. This is what causes the high MOMENTARY Lean condition.

So how do I adjust the pump then? Do I just adjust the timing screw so that it fires right after the slide goes up so the spray doesn't hit the slide? I have th 55 leak in there now, so I think that should be ok...

[chad502ex]

The AP timing screw under the black side cover of the fcr is to adjust the start of the quirt to be sure not to squirt the back of the carb slide. the leak jet provides the duration of the blast. the smaller the leak jet the longer the squirt.

Pull your carb off the intake and while holding it stab the throttle WOT to verify the squirt is not hitting the back of the carb slide. You want the fuel stream to just clear beneath the slide when the throttle is stabbed. adjust the screw beneath the black plastic cover to time the event.

Once installed and adjusted, replace the carb and ride to see if "timing" has reduced the effect. If not, and the bog is bad to almost stall the engine, buy a smaller leak jet from SUDCO.com and retry. I've had great luck with the 35 leak jet. It almost causes the AP to squirt for a full 2 seconds it seems. My FCR cam with 55. a 35 is the smallest offered.

hope this helps.

[bpimpdaddy21]

Originally posted by chad502ex
The AP timing screw under the black side cover of the fcr is to adjust the start of the quirt to be sure not to squirt the back of the carb slide. the leak jet provides the duration of the blast. the smaller the leak jet the longer the squirt.

Pull your carb off the intake and while holding it stab the throttle WOT to verify the squirt is not hitting the back of the carb slide. You want the fuel stream to just clear beneath the slide when the throttle is stabbed. adjust the screw beneath the black plastic cover to time the event.

Once installed and adjusted, replace the carb and ride to see if "timing" has reduced the effect. If not, and the bog is bad to almost stall the engine, buy a smaller leak jet from SUDCO.com and retry. I've had great luck with the 35 leak jet. It almost causes the AP to squirt for a full 2 seconds it seems. My FCR cam with 55. a 35 is the smallest offered.

hope this helps.

So I got to tune the A/P timing yesterday. I adjusted it in quite a bit (2+ turns), and I think I got that adjusted right, as the stream is just going under the slide. The quad still has the bog tho. It seemed to have gotten better, but not gone. This is both in neutral and under power.

I know it is a lean bog because to check I had the cover off the side of the carb, and I held the A/P open on the side so it was disabled, and the bog became very bad, just verifying the lean condition. So as you said my option now is to go to a smaller leak jet. My question is will it cause the squirt going into the engine to be richer as well as longer? Sometimes the bog will come on for like a quarter second then go, but if I really nail it the quad will die out.

Also, if the smaller leak jet doesn't seem to fix it, would the Boyesen quick shot fix it? I was reading on crfsonly and sooo many people swear it completely cured the bog. I just would rather spend $4 on a jet then $80.

On a better note, when I roll on the throttle the response seems 10x better with the FCR. You can almost hear it in the exhaust note. It sounds much crisper than before. I can't wait to get this thing dialed in all the way!

Let me know Chad, and thanks for all your help already!

BTW, I just went on sudco.com, and do you have to call them to order the jet? I don't see online ordering there....Is there any other place I could get the 35 leak jet from?

[bpimpdaddy21]

bump...

[chad502ex]

Originally posted by bpimpdaddy21
So I got to tune the A/P timing yesterday. I adjusted it in quite a bit (2+ turns), and I think I got that adjusted right, as the stream is just going under the slide. The quad still has the bog tho. It seemed to have gotten better, but not gone. This is both in neutral and under power.

I know it is a lean bog because to check I had the cover off the side of the carb, and I held the A/P open on the side so it was disabled, and the bog became very bad, just verifying the lean condition. So as you said my option now is to go to a smaller leak jet. My question is will it cause the squirt going into the engine to be richer as well as longer? Sometimes the bog will come on for like a quarter second then go, but if I really nail it the quad will die out.

Also, if the smaller leak jet doesn't seem to fix it, would the Boyesen quick shot fix it? I was reading on crfsonly and sooo many people swear it completely cured the bog. I just would rather spend $4 on a jet then $80.

On a better note, when I roll on the throttle the response seems 10x better with the FCR. You can almost hear it in the exhaust note. It sounds much crisper than before. I can't wait to get this thing dialed in all the way!

Let me know Chad, and thanks for all your help already!

BTW, I just went on sudco.com, and do you have to call them to order the jet? I don't see online ordering there....Is there any other place I could get the 35 leak jet from?
Everything you say perfectly describes a lean bog condition to me. You’ve done right by adjusting the AP timing manually with the carb off the engine to verify it is not squirting the back of the slide.

I know it sounds confusing, but a smaller AP leak jet installed into the float bowl cover prevents the AP circuit from pushing the fuel contained in the circuit back into the float bowl area. A smaller AP leak jet forces more of the fuel in the AP circuit to be pushed into the AP squirt jet in the throttle body bore.

A boysen quickshot kit contains a new AP push bladder than reduces the AP fuel push thru the circuit. You need more fuel not less.

Call SUDCO up and order the #35. you may have to fill a minimum order.

[bpimpdaddy21]

Thanks Chad...

I will either call SUDCO up and get the #35 leak jet, or I am going to stop at my dealer and see if by chance they may have one...

Also, I have a quickshot cover that a friend of mine is not using, and he said I could try it out to see if it helps. He doesn't have his FCR in yet, so its not being used. Basically I just want to see for myself if these things are actually worth the money spent on them, thats all. If it cures the bog also, then hey, all the better!

Again, thanks for your help though, I really appreciate it!