AP and how the adjustment works?

chilledspode · May 29, 2007

I have read the entire owner's manual twice and the repair manual and nowhere did I find a description of the AP adjustment. I have read Taffy's stuff in the Doc about bringing the gap down to 0.028".

My question is does a zero gap = zero squirt time?

The reason I ask is because I have Dale's jetting kit and he recommended removing the AP - if I can just adjust it out of the circuit then I may use that as a starting point.

Either way I need to know if less gap is lees squirt time....

Cheers

Mark

nb: did I miss the AP section in the manuals, by the way?

DaleEO · May 29, 2007

Chilled,

The less gap you have the MORE squirt you have. The stock setting is .100". This is on the Mark II FCR which is on your bike.

I'm not sure about the Mark I FCR which is the carb that Taffy did all of his work with, I believe.

Have a look at my gallery on page 4 and there is a picture of a set of instructions there from the boysen quick shot that I installed sometime ago. Mind you, I put the quick shot on for consistency, as the stock cover allegedly has a tendency to get an air bubble in it, which produces inconsistent amounts of fuel delivered by the AP.

Another way of setting the AP gap on a STOCK jetting set up is for the larger bikes like the 550 or 650 set the slide opening at 1.2mm and adjust the AP rod to have zero play to the AP diaphragm. For the 450 set slide opening at 1mm with zero play in the AP rod.

Remember, as you increase the idle speed you will decrease any play that might have been present in the AP rod to the AP diaphragm, or you will pre-compress the diaphragm . And visa versa, if you decrease the idle from your original setting, and it was just touching as you decrease the idle speed you could develop a lag or delay in the AP spuirt.

Hope this helps,

chilledspode · May 29, 2007

Thanks Dale,

I need to reread Taffy's work but I am sure he said reduce the squirt time by going down to 0.028" which is an inconsistent statement, based on what you have provided.

Hopefully Taffy will jump in here and sort me out...

Cheers

Mark

nb: from what you have said: the pump has a fixed range of operation and by opening the gap you delay the start and therefore reduce the AP squirt. From this it seems there is no way to have a small squirt early in the throttle movement then stop the squirt. I would think you would want a little squirt right off the bottom then stop and let the normal signal do the rest.

Taffy · May 29, 2007

yes i have the mark 1 carb. even the ones i've played with have been mark 1's but i have held a mark 2.

on the mark1 the plunger is stopped after .028" of travel. travel starts as you touch the throttle, therefore the squirt is short and only off a closed throttle position.

with the mark 2 i don't think it's science so come on!

the mark 2 i saw had a shoulder of cast aluminium that you could drill and tap to take a screw and locknut. there should already be a screw there to limit the total time. so by drilling and tapping you can start the squirt at different times as is your wish.

all you have to do is sit and study the action.....

regards

Taffy

chilledspode · May 29, 2007

Taffy,

I agree completely on your point about figuring it out by studying it, but I have a young family, am renovating our house and my riding season is measured in weeks - therefore any knowledge/experience I can glean efficiently from people here just means I get more fun time on the bike.

Selfish I realize, but I must be practical in these matters

Come Sept I will have 9-10months to fiddle around with things.

To give you some idea my 03 300exc has 70hrs on it after 4 seasons - it is my only dirt bike...

Taffy, thanks for sorting me out on the operation of the AP, I now know how I want to approach my low end stumble.

Cheers

Mark

nb: one last question if I may - at a 1000ft and 20C would you think a 48p too rich?

DaleEO · May 29, 2007

Taffy said:
yes i have the mark 1 carb. even the ones i've played with have been mark 1's but i have held a mark 2.

on the mark1 the plunger is stopped after .028" of travel. travel starts as you touch the throttle, therefore the squirt is short and only off a closed throttle position.

with the mark 2 i don't think it's science so come on!

the mark 2 i saw had a shoulder of cast aluminium that you could drill and tap to take a screw and locknut. there should already be a screw there to limit the total time. so by drilling and tapping you can start the squirt at different times as is your wish.

all you have to do is sit and study the action.....

regards

Taffy

Hey Taffy,

On the Mark II there is no screw to limit total time, just a screw adjustment as to when the squirt starts. The built in "squirt time" is governed by the length or height of the stop pin on the ap diaphragm itself. You can see a picture of this, and comparison in buzzards $40 FCR spruce up thread. The Honda diaphragm, as well as the one produced by JD has a much taller stop pin, thereby shortening the "squirt time" from approx. 3 seconds from the stocker, to .75 to 1 sec on the other diaphragm.

And yes you are correct, there is a shoulder cast into the body where one could drill and tap a hole (otherwise known as the BK mod) to make a stop that would adjust "squirt time". The other adjustment (see my gallery page 4) adjusts when the squirt begins. And, as I stated before, if you adjust the ap arm where there is just zero play in the ap rod, then adjust the throttle speed down, you will inadvertantly create a gap and delay the squirt timing, which could lead to a bog.

Also FYI, Pro Factory.com has another mod wherein they increase the size of the MAJ passage and install their own MAJ. I am not sold on this as of yet but wanted to pass it along to you.

Cheers!

husabutt · May 29, 2007

Some additional AP mod reading:

http://www.squadpage.com/pandora/Professor RedBeard450 How-To AP Mod.pdf

DaleEO · May 29, 2007

It's kind of ironic, redbeard is trying to lengthen the squirt time and we're trying to reduce it!!

They of course have the option of changing leak jets where most of us do not.

Thanks for posting the info Husabutt. If you look in the $40 fcr spruce up that buzzard wrote up a guy name chills who I pm'd with at thumpertalk whille insearch of the 450 manual posted in that thread along with the link to the readbeard thing. He was very open with his knowledge and he posted a link to the ongoing thread there.

Taffy · May 30, 2007

gee! what a great thread! a lazy arse who thinks i'll appreciate it amd someone who says i'm right but your memory is fading!

get on with it!

regards

Taffy

chilledspode · May 30, 2007

Dale/Husabutt- thanks for the link to the $40 FCR thread and redbeard stuff - I'll pull it down tonight

Taffy - that was unkind....

Cheers

Mark

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