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This Is Just ridicoulous-AP mod thrd

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As I'm on the never ending quest for ultimate performance, I was again messing with my bike and doing some contemplating as I looked at my AP linkage on my carb. As I messed with things to figure out how I could improve it's already stellar performance, I came across it. I was jacking with the AP "link lever" and realized that if the throttle was snapped very quickly, the spring pressure from the linkage was not enough to keep the "link lever" tight against the AP timing screw. The pressure from the AP circuit would momentarily overcome the linkage spring pressure, causing a lag in the AP squirt. I quickly realized that if I somehow connected the "link lever" to the AP timing screw, it would overcome this problem. After some thought, the best thing I could come up with was safety wire. I wrapped some safety wire around the "link lever" and the AP timing screw tab and "Voila", twas done. I reassembled the bike and tested it out and YIKES!!!, this thing hits instantaneously! The difference was more than notable. It is a little more involved than simply wiring things up, so my friend Chills put together a nice How-to" with pictures and everything...

So here it is....

Right-Click Save As:

http://www.squadpage.com/pandora/Professor%20RedBeard450%20How-To%20AP%20Mod.pdf

Enjoy!!

If you have any questions, shoot me a PM and I'll help out as much as possible. 👍

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Okay, if you pull the black plastic cover off the right side of the carb, you'll see the AP timing screw. There is the AP "link lever" which is a black plastic thingamabob that hold the AP pump rod. There is a little tab on the link lever that sits against the AP timing screw. What you need to do is safety wire that to the AP timing screw tab so they move in unison. I hope this helps because I ain't tearing my bike back apart just to get photos.

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If you never saw my thread about adjusting the AP timing while the bike was running, let me know. I highly recommend adjusting your AP timing that way, then wiring everything up.

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Redbeard,

I searched and couldn't find your AP timing post. Can you point me to it?

Also, is ET ever open during the week? Their web site is pretty weak schedule wise. I've got in-laws in AJ and would like to bring my bike down but since we're on the road on the weekends when we head down there I need a place to ride during the week.

BTW, wiring the link is pretty clever. I think I'll give it a shot. Cheap mods that work are the best mods.

Thanks,

BD

I don't think that they are open during the week. I'll see if I can find out and let you know. 👍

As far as the AP timing, here's the link.

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please explain???

The AP works off of the linkage spring pressure and all that happens is the linkage moves and allows the spring pressure to push the AP rod which pushes the diaphram, which pushes the fuel out of the AP cover into the motor. The problem is that the spring pressure isn't enough to instantly overcome the pressure that the fuel creates while trying to be shoved through a small orifice. By linking the AP link lever to the AP timing screw tab, it forces the rod to push the fuel instead of relying on the linkage spring pressure.

If you take the tank off and pull the black cover on the side of the carb, you'll see what I'm talking about. You have to safety wire the tab on the black plastic "link lever" to the AP timing screw tab so they are forced to move together.

I might break down and take a picture if you guys are having a hard time understanding, but I'm hoping that I can avoid that.

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Redbeard, nice find on the AP mod! I haven't messed with mine at all, considering my throttle response seems to be on par. But, I am not against tinkering with it a little this weekend. I have to wonder, though, why is the linkage set up this way from the factory, if a direct actuation (as with your mod) is a better setup? I am wondering if there will be any drawbacks with this mod. Such as, maybe too much fuel may be squirted in cases where you are whacking the throttle many times quickly, like in the whoops? Maybe the stock spring delay accounts for that....you have me wanting to tinker, now. 👍

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Redbeard, nice find on the AP mod! I haven't messed with mine at all, considering my throttle response seems to be on par. But, I am not against tinkering with it a little this weekend. I have to wonder, though, why is the linkage set up this way from the factory, if a direct actuation (as with your mod) is a better setup? I am wondering if there will be any drawbacks with this mod. Such as, maybe too much fuel may be squirted in cases where you are whacking the throttle many times quickly, like in the whoops? Maybe the stock spring delay accounts for that....you have me wanting to tinker, now. 👍

I honestly can't think of how it would cause an issue. The only drawback might be that it's too responsive and might make you use better throttle control. 👍

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Why not eliminate the spring all together, and fab some sort of plate to direct connect it.

Ill have to explore your find,but if you have felt a definate seat of the pants feel Im there

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I like the idea of instant AP function but I'm wondering about possible AP diaphragm damage. The AP is nothing more than a flexible diaphragm that when activated by the push rod will force gas through a hole into the intake. There is some resistance when forcing liquid through a small hole. Without the buffering effect of a spring linkage, something has to give. In this case it would be the diaphragm stretching because it can't push the gas through fast enough. The result after a short time may be a stretched out diaphragm that may not work as well as the original setup.

It's not hard to replace the diaphragm and it may be worth changing it out every couple of rides if the throttle response is that great.

Let us know if the results are lasting.

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hmmm interesting. I think twoup1200 makes a good point. I wonder what the diaphragm material is. Maybe it won't stretch or there is some aftermarket material that wouldn't. Man I can just imagine how impossible it might be to troubleshoot a stretched diaphragm. I'm wondering how much all of this has already been considered by Keihins design team.

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Hey Red,

Next time you have your bike apart, would you mind checking the the GAP on the AP timing with a feeler guage. You would have to check it from the AP Timing screw "Plate" to the black rotating AP Linkage. Right now I am sitting at .100, and wanted to know where your sat...

Thanks

Chris

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well the pics turned out crapier than i thought (i managed to spray carb cleaner in my left eye and part of my right so i my vision has been blurred all day 👍👍 )

here is what i think the AP timing thing is, the screw is right under the round throttle cable hookup

http://i8.photobucket.com/albums/a49/Ridewot911/IMG_0074.jpg

close up but really blurry

http://i8.photobucket.com/albums/a49/Ridewot911/IMG_0060.jpg

when the bike is on teh stand and you have gas running to it, will you be able to see the gas squirt out into the main bore??

When you wire it together, doesnt' that not allow the throttle to open to full throttle, because from what i saw, it opens to about half throttle or so (where i can see haveing it wired together as one unit helps) but then the screw continues to move out as you rotate throttle while the push rod has been completely depressed into the diaphram. if this doesn't make sense, let me knowill try to explain better.

oh yeah one more thing...if you want the squirt to come sooner, wouldn't you turn the adjust screw counter-clockwise so it moves further out and lets the diaphram start to compress sooner? and if you turn it clockwise so it moves in then it will not let the diaphram squirt until your farther into the throttle rotation?

and another question...

http://i8.photobucket.com/albums/a49/Ridewot911/IMG_0070.jpg

this is the throttle plate and what i think the book calls a free float? what the heck can the free float do? i mean i didn't see any passages for fuel or air and I can't figure it out..my eye really started to hurt so i started putting it back together before i figured it out.

non carb related:

http://i8.photobucket.com/albums/a49/Ridewot911/IMG_0075.jpg

while i was working on the bike, i drilled the 1/8" hole in the impeller for postive pressure on the seal.

http://i8.photobucket.com/albums/a49/Ridewot911/IMG_0076.jpg

P.S. remember to drain the bowl before you work on it or you dump gas all over you..if you don't at least take teh time to change jeans or you get nast gas burns from letting it sit..which i forgot about

http://i8.photobucket.com/albums/a49/Ridewot911/IMG_0061.jpg

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hey red played with the ap timing today,then wired it solid all i can say is;

WOW!!!!!!! great find "Profesor Redbeard"

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garage.php?do=viewattachment&attachmentid=12860

Pic?

Ok, when I first looked at this pic, it looked like as the throttle was opened, the black "cam" thing was pushed to the left by the metal screw and spring assembly. With that thinking, I was under the impression that tying them together accomplished nothing except pulling that black cam thing back quicker if the throttle was wicked fast several times. But, now that I look at it for a bit, it is apparent that the black cam is intended to stay in contact (by pressure from the shaft coil spring behind it) with the adjustment screw, and when the throttle is opened, both parts actually move to the right. And, by tying them together, you are ensuring that the black cam part follows the adjustment screw in a 1:1 fashion, no longer relying on that shaft spring to rotate the shaft? Is this correct? I have never really looked at those parts myself, to see how they function. Looks like a good mod to do. I wonder why the factory doesn't use a direct linkage setup there? Hey, TFB, if that is a photo you took, I think I have a better way to route your safety wire, for a more secure fit. Your routing looks like it could work its way off. I was thinking of more of an over and under type loop there. Hmmmm....how do I explain it...... I can't go out and tinker right now. I am watching the wee man while momma is at church. Maybe a little later, I can look at this thing in person and take a pic of the loop I am thinking of. I am still trying to think of why the factory isn't using a linkage if it is the way to go..... 👍

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Allright, I bet your idea gives good response.

But if it was so simple, why did'nt Keihin bolt that thing together to begin with?

Now, I bet that the reason is, that too consentrated amount of gas enters the combustion, without being blended properly with inlet-air.

The cause of this would be that the oil film will be wiped away from the cyl. bore, causing excessive wear.

The spring part of the AP mechanism, is there to meter the "squirt" amount.

The Boyesen "quick shop" does'nt spray more fuel than your std. cover. It just does it one little bit quicker. 👍

Well I got no proof of this, but that does'nt make it wrong.

What do you think about it?

I love my boyesen AP cover by the way. 👍

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Allright, I bet your idea gives good response.

But if it was so simple, why did'nt Keihin bolt that thing together to begin with?

Now, I bet that the reason is, that too consentrated amount of gas enters the combustion, without being blended properly with inlet-air.

The cause of this would be that the oil film will be wiped away from the cyl. bore, causing excessive wear.

The spring part of the AP mechanism, is there to meter the "squirt" amount.

The Boyesen "quick shop" does'nt spray more fuel than your std. cover. It just does it one little bit quicker. 👍

Well I got no proof of this, but that does'nt make it wrong.

What do you think about it?

I love my boyesen AP cover by the way. :bonk:

Fuel washing away the oil from the cylinder wall? That's pretty far fetched. The spring is not a meter, the diaphram, leak jet and adjustment screw do that. The Quickshot refills it's reservior quicker than the stock cover, and yes, squirts more fuel because the bowl actually hold more fuel. It sounds like you are making up reasons that your Quickshot wasn't simply a waste of money. 👍

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i already have the boysene quick shot on my bike. Would it be a waste of time to do this or would it really make a difference? anyone else with the quickshot do this?

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I think if the spring was shimmed or a stiffer spring was used it would give the same result with out any possible problems 👍

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I might have to make the long travel to your house Red. Of course I'll have to refuel and take a snack, but otherwise I can make it.

I'd like you to help me fine tune my beast's carb. For some reason, jetting is still something that I can't seem to do well.

ben

Chills just came out to my house today and we messed with his bike. Hopefully he can ride it soon to give us an update. 👍

You're welcome any time.

Revision of mod.

There is a possibility that the AP diaphram can bottom out. This won't cause the throttle to not open all the way because the gap is pretty minor, but it will force the link lever to flex. Here's the trick. After pulling the black carb linkage cover off, you want to open the throttle all the way and see if there is a gap between the link lever and the AP timing screw. If there is, turn the screw in and close the gap before you wire them together. Mine did not have this problem because my AP diaphram rivet was shortened, but Chills' bike did. It was a very small amount, and after testing, throttle response on his bike was significantly improved, so the change in AP timing did not hinder this mod's effectiveness.

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Chills just came out to my house today and we messed with his bike. Hopefully he can ride it soon to give us an update. 👍

You're welcome any time.

Revision of mod.

There is a possibility that the AP diaphram can bottom out. This won't cause the throttle to not open all the way because the gap is pretty minor, but it will force the link lever to flex. Here's the trick. After pulling the black carb linkage cover off, you want to open the throttle all the way and see if there is a gap between the link lever and the AP timing screw. If there is, turn the screw in and close the gap before you wire them together. Mine did not have this problem because my AP diaphram rivet was shortened, but Chills' bike did. It was a very small amount, and after testing, throttle response on his bike was significantly improved, so the change in AP timing did not hinder this mod's effectiveness.

Hey Red,

Thanks again bud!! 👍

Here's what we did, we adjusted the Needle back to Stock height, took the 175 MJ and went back to the 168 MJ, pulled the 45 PJ, and went back to the 42 PJ. We then started looking at the AP timing and how the effects would be by wiring the Link lever to the AP Timing screw housing. Since Red did some mod work to his AP bowl, he did not encounter the same issue. What appears to be happening is, when you go WOT, the AP Diaphragm rod bottoms on the AP bowl, which in turn does not allow the Link Lever to make a complete rotation along with the AP timing screw. The was probably about 1/16 to 1/8th of an in gap between WOT and 3/4 throttle. When we did wire them together, the stress of the AP diaphragm rod since it would not go all the way down when WOT, the stress was transfered to the AP Link Lever and the AP Set screw arm. Along with the added stress, it actually binded at WOT, after carefully examining where the stress was occurring, we had 2 choices. File down the bottom of the AP bowl to allow the AP Diaphragm Rod to go further down and compensate for the GAP, or, Adjust the AP timing screw to meet the AP Link Lever at WOT. We took the lesser of 2 evils, and set the AP timing screw to meet the AP Link Lever at WOT. Once they were met, we then wired the AP Link lever to the AP timing screw bracket in order to relieve the stress of any parts. Put everything back together, and Presto!! Pretty damn dead on throttle response. I am assuming that with the AP Link Lever and the AP Timing screw wired together, it will put some added stress on the diaphragm because there is no give.

Red and I concluded that with a full AP bowl, the AP Diaphragm rod, which is connected to the Link lever was almost like a self governing system, since the AP Link lever is also spring actuated with the throttle, if for some reason the AP Diaphragm rod didn't stay in unison when you twisted throttle under quick acceleration, it would eventually catch up. In other words, the AP Diaphragm rod, since it was pushing down on the diaphragm, and forcing fuel into the carb, that motion of it compressing the diaphragm with fuel would cause some form of resistance, which is why the AP link lever is under spring tension. By wiring the AP Link lever to the AP timing screw housing, you are eliminating that governing effect, and in fact forcing the fuel through the AP at the same rate as you twist the throttle.

God, I hope that made sense. If you have any questions, feel free to shoot a PM or post, its pretty trick how we did it, but I think I will go ahead and get an AP Diaphragm just in case because we are now forcing the diaphragm to work at the same rate as the throttle, rather than letting it overcome the AP Link Lever spring to catch up to where the throttle, we are forcing it to work.

Thanks again Red...

U da Man :bonk:

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