Accelerator Pump Tuning

At the risk of pissing off one of the old timers for asking a question that's already been addressed in the Stickies, I need some clarification on the procedure that William1 posted for adjusting the AP.

"Accurate" route

As directed in the post, I held up the slide with an 8mm blank and backed out the AP adjustment screw. However, when we are talking about "Turn the AP timing screw so the play just barely goes away." Are we talking all the way IN or OUT? Because if I turn it all the way OUT, there is no end to the "play" unless I raise the slide higher. At 8mm, the black AP lever is still leaning against the screw mount (even if the screw isn't in it). The only clear separation between the AP lever and AP screw occurs at WOT.

"Not as accurate" route

Backed out the idle screw until the slide sits on the base of the bore. However, the "Set the timing gap between the cam and the screw to be .010" again has me confused since I can't get the the AP lever and AP screw to show any light between them outside of WOT.

I've looked at a dozen videos on YouTube and have seen the TT video showing suggestions on the 2.5mm measurement, but what I don't get is what is being measured at a distance of 2.5mm??? Are we talking the base of the AP screw MOUNT to the AP LEVER? Or is it the length of actual AP adjustment screw that is protruding from it's mount?

Again, for give me for my ignorance (especially William1), I'd just like to get my AP dialed in and the sticky is doing nothing more than leaving me frustrated due to the little bits of info it seems to be lacking.

Thanks for the help!

At the risk of pissing off one of the old timers for asking a question that's already been addressed in the Stickies, I need some clarification on the procedure that William1 posted for adjusting the AP.

"Accurate" route

As directed in the post, I held up the slide with an 8mm blank and backed out the AP adjustment screw. However, when we are talking about "Turn the AP timing screw so the play just barely goes away." Are we talking all the way IN or OUT? IN. LET IT TOUCH, THEN BACK IT OUTBecause if I turn it all the way OUT, there is no end to the "play" unless I raise the slide higher. At 8mm, the black AP lever is still leaning against the screw mount (even if the screw isn't in it). The only clear separation between the AP lever and AP screw occurs at WOT.I DO IT WITH A 3MM SPACER, NOT 8MM

"Not as accurate" route

Backed out the idle screw until the slide sits on the base of the bore. However, the "Set the timing gap between the cam and the screw to be .010" again has me confused since I can't get the the AP lever and AP screw to show any light between them outside of WOT.

I've looked at a dozen videos on YouTube and have seen the TT video showing suggestions on the 2.5mm measurement, but what I don't get is what is being measured at a distance of 2.5mm??? Are we talking the base of the AP screw MOUNT to the AP LEVER? Or is it the length of actual AP adjustment screw that is protruding from it's mount?

Again, for give me for my ignorance (especially William1), I'd just like to get my AP dialed in and the sticky is doing nothing more than leaving me frustrated due to the little bits of info it seems to be lacking.

Thanks for the help!

You can avoid all of this measuring by simply tilting up the subframe, and viewing the squirt. You want to adjust it so it just barely misses the slide, everytime you whack the throttle or fast roll in open. Turn the linkage screw a bunch of turns either way so you can see the change easily, then adjust it correctly. Do it indoors, with a flash light, while someone else does the throttle. YOUR LEAK JET NEEDS TO BE CORRECT at about 50, before you try any of this.

The quick way to adjust is back out the idle screw so it won't idle anymore, then adjust the linkage so it just touches the cam, then back counter clockwise 1/4 to 1/2 a turn.

Well, I'm at a #40 leak. So I guess the next thing to do is just ride it and test as I go!

Though is the official "bog" that the sticky refers to that point when you are riding, hit the throttle and rather than getting that POP of acceleration where it feels like it wants to do a wheelie, it's kind of a slow lag? I have to venture a guess that the lag (if that's what the "bog" is) is due to the lengthy spray of fuel from the AP into the engine in comparison to what the o-ring mod is supposed to do with the QUICK burst.

Do I have that correct?

Well, I'm at a #40 leak. So I guess the next thing to do is just ride it and test as I go!

Though is the official "bog" that the sticky refers to that point when you are riding, hit the throttle and rather than getting that POP of acceleration where it feels like it wants to do a wheelie, it's kind of a slow lag? I have to venture a guess that the lag (if that's what the "bog" is) is due to the lengthy spray of fuel from the AP into the engine in comparison to what the o-ring mod is supposed to do with the QUICK burst.

Do I have that correct?

More or less. But, the O ring mod is very inconsistent, and temporary. The ring stretches with heat, and stays stretched after a while, then breaks.

This is a permanent fix:

http://www.mergeracing.com/products/AcceleratorPumpSpring.php

BTW, it is not a 8.0 mm blank, it is supposed to be a 0.8mm

Setting it visually is terribly inaccurate.

BTW, it is not a 8.0 mm blank, it is supposed to be a 0.8mm

Setting it visually is terribly inaccurate.

Hell, give it a whole 1mm. I still don't see daylight between the 2 components until WOT. And the "barely any play"? Again, is this supposed to be a similar process to gaping valves with a feeler gauge? If so, I got no separation between the 2 components to measure... Even with the screw removed!:busted:

Hell, give it a whole 1mm. I still don't see daylight between the 2 components until WOT. And the "barely any play"? Again, is this supposed to be a similar process to gaping valves with a feeler gauge? If so, I got no separation between the 2 components to measure... Even with the screw removed!:banghead:

The spacer goes under the SLIDE with the idle screw turned all the way out.

Then you adjust the linkage screw till it just touches, then back 1/2 turn.

That is your starting point. You adjust from there by riding it, or viewing the squirt, which as William1 said, ain't easy. You really have to film it in slomo to see it really well....but it does work.

accel%20pump.jpg

Not an FCRMX, but close enough....

I've bottomed out the idle screw to where the side is resting comfortably on the bore of the carb. Got that part...

Here's the hiccup...

Directions say to put a .8 mm blank under the slide to RAISE it. However, what does raising the slide .8mm accomplish? the AP screw is still touching the black lever! If raising the slide .8mm is supposed to allow you to "gap" the distance between the AP screw and the black lever, they are still touching.

Again, as William1 said "Turn the AP timing screw so the play just barley goes away." Well, if we were adjusting the valves on my 76 VW Bus, I'd know EXACTLY what the "play" is we are adjusting out (where the adjustment screw is NOT touching the lever... yet). However, in a valve adjustment (as you already know) we are trying to create a tiny gap in between the two things that are going to be touching. In the case of the AP screw and black lever, there is no space created until I am near WOT. Is that in fact what we are trying to accomplish? If not, then that is what I need clarification on.

Sorry for being such a PITA, but for being as mechanically inclined as I am, this process is quite puzzling.

I've bottomed out the idle screw to where the side is resting comfortably on the bore of the carb. Got that part...

Here's the hiccup...

Directions say to put a .8 mm blank under the slide to RAISE it. However, what does raising the slide .8mm accomplish? the AP screw is still touching the black lever! If raising the slide .8mm is supposed to allow you to "gap" the distance between the AP screw and the black lever, they are still touching.

Again, as William1 said "Turn the AP timing screw so the play just barley goes away." Well, if we were adjusting the valves on my 76 VW Bus, I'd know EXACTLY what the "play" is we are adjusting out (where the adjustment screw is NOT touching the lever... yet). However, in a valve adjustment (as you already know) we are trying to create a tiny gap in between the two things that are going to be touching. In the case of the AP screw and black lever, there is no space created until I am near WOT. Is that in fact what we are trying to accomplish? If not, then that is what I need clarification on.

Sorry for being such a PITA, but for being as mechanically inclined as I am, this process is quite puzzling.

You can't adjust it like valves. There is no 'set' spacing. It's plastic, and non-precision metal. No precision enough to have a 'tolerance'.

You start with the stock setting (which is in the manual) and adjust from there, buy RIDING it and testing it. Skip the spacer, skip the adjustment, and pull up your subframe and see what it does, when it looks right, ride it, adjust as needed.

I get what you're saying Krannie. However, for the sake of someone else that might be looking to adjust there's and can't understand the items I'm pointing out from the Sticky, I'm simply looking for clarification.

It says in the !!!NEWBIE SURVIVAL GUIDE!!! that folks should read the stickies and search the forum BEFORE asking a question. So with that said, I'm simply trying to clarify the wisdom that William1 bestowed upon us. His directions are a lifesaver, they just need clarity in a few spots for idiots like me!

Personally, I plan to ride with a screw driver in my teeth for a little while to get that POP where it needs to be. And regarding the o-ring mod, I agree that it's not a permanent mod... I plan to do the wire tie after I get the whole AP dialed in.

You know you could always adjust the AP when it's running on the stand.......after it's warmed up and you'll get it perfect....just listen to it.

I've had problems with that plastic nut on the hot start....hanging the idle.

... I plan to do the wire tie after I get the whole AP dialed in.
FYI, the wire tie isn't the best solution. The reason for the o-ring is to allow the arm (and throttle) to still move (o-ring stretches) after the button on the AP diaphragm has bottomed out. With a solid connection between the two, eveything stops when the button bottoms out. You could grind the button down or buy Honda diaphragms that have different length buttons, but that is also going to change the tuning of the AP. The problem is that the stock AP spring is too weak and there is usually a delay between throttle action and AP lever movement. As mentioned, the Merge Racing AP spring is the best solution.
FYI, the wire tie isn't the best solution. The reason for the o-ring is to allow the arm (and throttle) to still move (o-ring stretches) after the button on the AP diaphragm has bottomed out. With a solid connection between the two, eveything stops when the button bottoms out. You could grind the button down or buy Honda diaphragms that have different length buttons, but that is also going to change the tuning of the AP. The problem is that the stock AP spring is too weak and there is usually a delay between throttle action and AP lever movement. As mentioned, the Merge Racing AP spring is the best solution.

Can't get away from how big a deal this is....!

Krannie, Are you saying that the Merge AP spring is a great deal, price wise, for what it does? Maniac

Krannie, Are you saying that the Merge AP spring is a great deal, price wise, for what it does? Maniac

I"m saying, that you cannot get the accelerator pump to even work correctly until you replace the stock spring with the merge racing or R&D spring.

O-rings don't work, wire-ties don't work, saftey wire doesn't work, so don't bother, unless you like taking your carb off every 3 or 4 months to fish out the broken o-rings, wire-ties, and saftey-wire bits.

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