Wiring the AP pump?


50 replies to this topic
  • Nalgene

Posted March 15, 2006 - 08:19 PM

#21

To save aford541 the reply again. In aford541 garage there is a pic of the wired up Acelerator pump mod. From that pic you should be able to get a fairly good idea of what needs to be done. :thumbsup:

  • RideRaceLive123

Posted March 15, 2006 - 09:37 PM

#22

I did this mod this past weekend and noticed no more low end bog and dare say ( it didnt want to hot stall )

Real quick mod i think any gauge saftey wire will work.. I kinda bent the wire in a U shape and took the ends and kinda curled them up wards like > C <
to loop it around the AP and throttle thingy.. :thumbsup:



Did you grind down the Diaphram rivet and turn in the accelerator pump screw until it meets with the AP link lever like the CRF guys? Or did you only safety wire?

What did you do aedwards07? Only safety wire?

  • Baron Von Beard

Posted March 15, 2006 - 11:06 PM

#23

Did you grind down the Diaphram rivet and turn in the accelerator pump screw until it meets with the AP link lever like the CRF guys? Or did you only safety wire?

What did you do aedwards07? Only safety wire?


The best way to do it is to shorten the diaphragm rivet and then wire it up. You want to make sure the AP timing is set correctly first. Screwing the timing screw in is only to take up the gap between the link lever and the cam follower on the linkage if you don't shave the rivet down. If you wire it up without either shaving the rivet down (preferred method) or turning the screw in to close the gap, the diaphram rivet will bottom out and will create binding in the throttle linkage and possibly break the link lever. By turning the screw in instead of shortening the rivet, you are messing up the AP timing and will not get the best result although the bikes we have tried it on had better response than a properly timed AP squirt that wasn't wired up. Be patient, the article will be up very soon and will answer all of your questions. :thumbsup:

  • Nalgene

Posted March 16, 2006 - 05:40 AM

#24

Honstely I just heard about the whole ap wiring thing from NCmountain and I saw that ford had a pic of it. So I just went to town and even though I never adjusted the screw all the way down or grinded a rivet I noticed an improvement in response.

Perhabs it could get even better if I applied these new settings. :thumbsup:

  • Baron Von Beard

Posted March 16, 2006 - 07:26 AM

#25

Honstely I just heard about the whole ap wiring thing from NCmountain and I saw that ford had a pic of it. So I just went to town and even though I never adjusted the screw all the way down or grinded a rivet I noticed an improvement in response.

Perhabs it could get even better if I applied these new settings. :thumbsup:


You need to make sure that the AP isn't bottoming out and creating a bind! You could either bind the throttle open and/or break the link lever if you do not check for binding. You can't simply wire it up and call it good. There's a reason that you have to either turn the screw in or shorten the rivet. Fix it before you ride it or something could happen.

  • Chills

Posted March 16, 2006 - 07:45 AM

#26

OK Guys, Just made the How-To Article for his Public at

http://www.thumperta...560#post3137560

PDF format!! Enjoy!!

  • Ga426owner

Posted March 16, 2006 - 08:22 AM

#27

OK Guys, Just made the How-To Article for his Public at

http://www.thumperta...560#post3137560

PDF format!! Enjoy!!


Great info:

Who wants to be the guinea pig for the Yami side?

FYI I recommend purchasing other diaphrams rather than cutting your stock diaphram rivet/rod. I have purchased 3 different diaphram sizes from Yamaha for my 03 (06 has a FCR MX39)- they are avail - I will try to get part numbers - The stock leakjet in the 06 is a #55
here is link to Sudco - leak jet options:
http://www.sudco.com...alog105/095.pdf

some handy AP pump tuning secrets: http://www.thumperfaq.com/ap.htm#Dia

Diaphram options: all have different length diaphram rivet/rods (should be for 03-06)
5JG-14940-18-00
5JG-14940-17-00 - STD
5JG-14940-19-00
5JG-14940-15-00

Leakjet options: for the 06
4JG-1494F-07-00 #50
4JG-1494F-11-00 #60
4JG-1494F-09-00 #55 STD
4JG-1494F-13-00 #65
4JG-1494F-05-00 #45

Leakjet options for the 03
4MX-1494F-01-00 #35
4MX-1494F-02-00 #38
4MX-1494F-03-00 #40
4MX-1494F-04-00 #42
4MX-1494F-05-00 #45
4MX-1494F-06-00 #48
4MX-1494F-07-00 #50

Hope this helps :thumbsup:

  • Baron Von Beard

Posted March 16, 2006 - 08:32 AM

#28

Great info:

Who wants to be the guinea pig for the Yami side?

FYI I recommend purchasing other diaphrams rather than cutting your stock diaphram. I have purchased 3 different diaphram sizes from Yamaha for my 03 (06 has a FCR MX39)- they are avail - I will try to get part numbers - The stock leakjet in the 06 is a #55
here is link to Sudco - leak jet options:
http://www.sudco.com...alog105/095.pdf

some handy AP pump tuning secrets: http://www.thumperfaq.com/ap.htm#Dia



Good info, although I am unaware of a diaphram that has a short enough rivet to allow full travel with the cam follower. If it's too long, it will stop the link lever from moving and create a bind in the throttle linkage. That's why I recommend shortening the rivet that you have. This will insure that the AP does not bottom out and create bindage, plus you don't need to spend money on a diaphram that may or may not work.

  • JoeJoe03

Posted March 16, 2006 - 08:34 AM

#29

THANKS!!!!!!!!!!!

You guys flat out ROCK :thumbsup: :thumbsup:

Will this procedure work for my '03 YZ450F??

Will it not work well if I dont change the leak jet??? What size leak jet would you recommed for this bike after the mod?? (I have a quickshot also)


Thanks! :bonk:

  • Baron Von Beard

Posted March 16, 2006 - 08:40 AM

#30

THANKS!!!!!!!!!!!

You guys flat out ROCK :thumbsup: :thumbsup:

Will this procedure work for my '03 YZ450F??

Will it not work well if I dont change the leak jet??? What size leak jet would you recommed for this bike after the mod?? (I have a quickshot also)


Thanks! :bonk:


It will help cure the bog without changing leak jets, although the mid transition will more than likely be rich due to the extra fuel shot. I am at that point right now. The bike is very responsive, but a little rich right in the middle. For the time being, I leaned out my needle to try and make up for the extra fuel until i get some leak jets.

You'll have to do your own experimenting with the leak jets. I have yet to get some, so I can't point you in the right direction. Sorry. Once I figure it out, I'll post it. It will work on your bike. The carbs are the same.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • Ga426owner

Posted March 16, 2006 - 08:47 AM

#31

Good info, although I am unaware of a diaphram that has a short enough rivet to allow full travel with the cam follower. If it's too long, it will stop the link lever from moving and create a bind in the throttle linkage. That's why I recommend shortening the rivet that you have. This will insure that the AP does not bottom out and create bindage, plus you don't need to spend money on a diaphram that may or may not work.


The diaphram options listed all have different length rivets/rods :thumbsup:

  • Ga426owner

Posted March 16, 2006 - 08:54 AM

#32

OK Guys, Just made the How-To Article for his Public at

http://www.thumperta...560#post3137560

PDF format!! Enjoy!!


I request that you get with the moderators to make this a sticky on the jetting forum :thumbsup:

  • Baron Von Beard

Posted March 16, 2006 - 08:55 AM

#33

The diaphram options listed all have different length rivets/rods :thumbsup:



I understand that, but whether or not they will allow full throttle travel when wired without binding remains to be seen. That's why I say to shorten the stock one. You really don't need the rivet any longer with this mod because it needs to follows the full travel of the throttle.

  • JoeJoe03

Posted March 17, 2006 - 04:25 PM

#34

OK..

I just finished installing both the Boyesen Quickshot and did the AP Wire Mod :bonk:

Boyesen Quickshot: '03 YZ450F

I didnt have to take the carb off! I took the panels off and the seat just so I could undo the Hot Start from the carb. I had to undo this to be able to turn the carb cuz it gets in the way.

I sat on the left side (gear shifter) turned the carb towards me and went to town. I had to find a really short phillips screwdriver to deal with the clearance, but it all worked well. Replaced the stock AP cover with the Boysen and that was it. I turned the timing screw out 1/2 turn as recommended by Boysen:thumbsup:

AP Wire Mod: '03 YZ450F

When I took the AP cover off I noticed that the diaphram rivet on my '03 yz450 was very short (2mm) Because of this I did not shorten it any more. (I hope this was a good call??????)
I sat on the right side (rear break) and had no problem accessing the carb from there. This bike has access without having to take anything apart. I took the cover off and checked the gap with a wide open throtle. The gap was very small (1/32") All I did was screw in a little just to close that little gap while at WOT. Then I used a rubber O ring to secure the back of the screw to the little black plastic thingy (I forgot the name of this)...lol I put the carb back together and that was it for me! :thumbsup:

Questions:

Why did I have to use the O ring????? What is the purpose to hold the screw securly to the black plastic part since there is no gap at WOT anymore? I couldnt understand this... :thumbsup:

Does it sound like I may have missed anything ?????


THANKS again buds!!!!!!!!!!!!!!!!!!!

  • Baron Von Beard

Posted March 17, 2006 - 05:01 PM

#35

OK..

I just finished installing both the Boyesen Quickshot and did the AP Wire Mod :bonk:

Boyesen Quickshot: '03 YZ450F

I didnt have to take the carb off! I took the panels off and the seat just so I could undo the Hot Start from the carb. I had to undo this to be able to turn the carb cuz it gets in the way.

I sat on the left side (gear shifter) turned the carb towards me and went to town. I had to find a really short phillips screwdriver to deal with the clearance, but it all worked well. Replaced the stock AP cover with the Boysen and that was it. I turned the timing screw out 1/2 turn as recommended by Boysen:thumbsup:

AP Wire Mod: '03 YZ450F

When I took the AP cover off I noticed that the diaphram rivet on my '03 yz450 was very short (2mm) Because of this I did not shorten it any more. (I hope this was a good call??????)
I sat on the right side (rear break) and had no problem accessing the carb from there. This bike has access without having to take anything apart. I took the cover off and checked the gap with a wide open throtle. The gap was very small (1/32") All I did was screw in a little just to close that little gap while at WOT. Then I used a rubber O ring to secure the back of the screw to the little black plastic thingy (I forgot the name of this)...lol I put the carb back together and that was it for me! :thumbsup:

Questions:

Why did I have to use the O ring????? What is the purpose to hold the screw securly to the black plastic part since there is no gap at WOT anymore? I couldnt understand this... :thumbsup:

Does it sound like I may have missed anything ?????


THANKS again buds!!!!!!!!!!!!!!!!!!!



Because the only thing pushing the AP diaphragm is the spring pressure on the black link lever, which isn't enough to overcome the fuel pressure of the diaphragm trying to push the fuel through the little hole that it needs to go through. You're AP now shoots instantly because it follows the throttle movements exactly, instead of having a lag time. Does that clear it up?

  • JoeJoe03

Posted March 17, 2006 - 07:46 PM

#36

clears it up just fine!

thanks again and as I said before.....Awesome job on that manual :thumbsup:

couldn't have been more professional and thourough!

tomorrow I will take it out to the track for some good ridin :thumbsup:

my feedback on performance will follow.............

  • motobark

Posted March 18, 2006 - 12:13 AM

#37

Hey guys, I didn't read all of this thread or the entire pdf, but I did see that you're making the accel pump squirt all the way to full throttle. The accel pump isn't needed after about 1/2 throttle. You also don't want any more fuel than is necessary to eliminate a lean hesitation when the throttle is opened quickly. If you're on and off the throttle a lot (like coming into a turn with the clutch in, keeping the revs up) you'd be dumping way too much fuel with these mods.
Remember, the pump is only supposed to come into play on a quick throttle application. I personally have reduced the accel pump volume and duration on all the big YZ's I've had and ended up with crisp, clean power with no hesitations or overly rich blubbering. But then again I've spent hundreds of hours jetting and riding big 4 strokes before they even had accel pumps. I'm just saying keep in mind, bigger isn't always better. If your jetting is right, you should need very little accel pump to eliminate hestitations. And you certainly don't need the pump to be spraying at 3/4 to full throttle.

  • bg10459

Posted March 20, 2006 - 11:10 AM

#38

Diaphram options: all have different length diaphram rivet/rods (should be for 03-06)
5JG-14940-18-00
5JG-14940-17-00 - STD
5JG-14940-19-00
5JG-14940-15-00

Do you know the length of each diaphragm listed? I need between 1 and 2mm less to prevent the binding

Who wants to be the guinea pig for the Yami side?

I’ll be doing it, just don’t wait on me because it’s going to take some time before I get to test.

  • Baron Von Beard

Posted March 20, 2006 - 11:23 AM

#39

Hey guys, I didn't read all of this thread or the entire pdf, but I did see that you're making the accel pump squirt all the way to full throttle. The accel pump isn't needed after about 1/2 throttle. You also don't want any more fuel than is necessary to eliminate a lean hesitation when the throttle is opened quickly. If you're on and off the throttle a lot (like coming into a turn with the clutch in, keeping the revs up) you'd be dumping way too much fuel with these mods.
Remember, the pump is only supposed to come into play on a quick throttle application. I personally have reduced the accel pump volume and duration on all the big YZ's I've had and ended up with crisp, clean power with no hesitations or overly rich blubbering. But then again I've spent hundreds of hours jetting and riding big 4 strokes before they even had accel pumps. I'm just saying keep in mind, bigger isn't always better. If your jetting is right, you should need very little accel pump to eliminate hestitations. And you certainly don't need the pump to be spraying at 3/4 to full throttle.


You are correct. Unfortunately we have traded a shorter duration for an instant response, so leak jet changes have become necessary with this mod to get the most performance out of it. By wiring things up, the duration in time is actually faster than not being wired with less duration in travel by the diaphragm. So what we are getting is a fast squirt that does last for a full throttle twist, but it is actually happening faster than it did before, so the duration in time is down. The only problem is that it now squirts more fuel in less time, so we must change to a larger leak jet to get the squirt back in check. After the correct leak jet is installed, we now have a very fast, instant shot of fuel that reacts very quickly to throttle movement. I have noticed the biggest improvement in technical rhythm sections where you are on and off the throttle quickly. Before the AP would lag long enough to bog because the throttle was opening and closing so quickly that the AP link lever would pretty much just hang out in one spot, whereas now it follows the movements of the throttle exactly and always has a squirt whenever it is needed.

  • ncmountainman

Posted March 20, 2006 - 03:42 PM

#40

when i did it i just set the AP screw where it ran the best and wired it shut,i run it with the boyesen cover and have noticed no binding or hanging anywhere :thumbsup: lucky maybe,but the feller that i got the info from did not mention all that rivet crap. it certainly responds quicker but i noticed on my 1st ride that my fuel economy did suffer.





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