AP mod


17 replies to this topic
  • speedracerlb

Posted October 07, 2009 - 07:25 PM

#1

OK, I have seareched for a how to do maybe with pictures AP mod for a 07 or newer WR450 and can't find it. Can anyone help? Bought an 09 and have done all the other mods going to rejet it this weekend. I would like to do it all at once. thnx again this site is great:banana:

  • MT-01

Posted October 07, 2009 - 07:28 PM

#2

I havent heard of any AP mods....???????

Got a R&D Powerbowl with Oversized AP on my 07

Fitted a Boysen Quickshot 3 to an 08 last night....

What do you think this mod will do or consist of???

Pat

  • speedracerlb

Posted October 07, 2009 - 07:44 PM

#3

I havent heard of any AP mods....???????

Got a R&D Powerbowl with Oversized AP on my 07

Fitted a Boysen Quickshot 3 to an 08 last night....

What do you think this mod will do or consist of???

Pat


It takes away the bog, so I have been told and read about.

  • CORider63

Posted October 07, 2009 - 08:49 PM

#4

You wrap a rubber O-ring around the two AP linkage arms to essentially tie them together. Two thicknesses of O-rings are included in the JD Jetting kit along with instructions.

I installed the heavier of the two O-rings on my 2007 WR-450 and have never had another problem.

  • William1

Posted October 08, 2009 - 07:12 AM

#5

O-Ring Mod and AP Tuning

  • CORider63

Posted October 08, 2009 - 07:31 AM

#6

O-Ring Mod and AP Tuning

William,

Is that link in any of the FAQ / stickies? I looked and couldn't find it.

  • William1

Posted October 08, 2009 - 09:48 AM

#7

No, actually, the thread is in the DRZ forum, having risen from the need to get the AP figured out for the FCR-MX for all the conversions done there. Yeah, the thread is long. Yeah, I made a few mistakes (Brain is not always connected to hands typing....must resist forces making me stupider).

Bottom line is this for the Bog
1) Jet you bike for normal riding. Ignore the bog for now
2) Oring or use a stiffer spring on the AP cam. If you want to oring it. go to Lowes/Home Depot/a good plumbing store, buy a box of #78 orings, 10 for $2.00. Merge Racing makes the spring. Orings break but are easy to change (2 minutes tops, on bike). The spring will last forever.
3) You want to run the largest leak jet and not have a bog. Though for many people, this is not worth the effort to figure out. A #40 to $55 is good for nearly anyone. If you want, spend the extra money on an adjustable LJ. Then 'selecting the right one' is a simple matter of tweaking a screw. There are a bunch of them on the market. I like the Merge Racing one. But no matter what one you get, get one with the adjuster coming out the left side. Last thing you want to do is tweak a screw right next to a 500 degree exhaust pipe.
4) Adjust the AP timing. This is what no one wants to do. So simple and easy too, go figure. You remove the cover over the throttle wheel. Get you bike all heated up. Turn the screw in 1/2 ride a lap, turn the screw again. Keep doing this until the bog just goes away during actual normal riding. Yeah, you may have a bog reving the engine in the garage, but does that matter? To eliminate the bog right off of idle can require a increase in idle speed to about 2K, a soldered closed LJ and the timing screw cranked all the way in. Be aware if you make the bike bog proof at idle speeds, your fuel consumption will suffer. Also, every nervous twitch will shoot extra fuel in and stead state riding may be a pain.

Now, if in time, you find you have a bog at wide throttle openings, you may want to try a larger LJ. But it is a balance between low speed and high speed bogging.

  • viffer vern

Posted January 04, 2010 - 10:38 PM

#8

Be aware if you make the bike bog proof at idle speeds, your fuel consumption will suffer. Also, every nervous twitch will shoot extra fuel in and stead state riding may be a pain.


On my first ride out with my FCR my bike seemed bog proof, and the fuel economy did suffer. Can you explain why this happening?

This is an older style FCR with the ap wired together and the diaphram rivet milled down. It really ran well but seemed to use twice the amount of fuel as before.

  • William1

Posted January 05, 2010 - 03:04 AM

#9

If.... you run a small leak jet and the linkage is tightly wired together (and with an old style carb, did you do the taffy mod yet?) every tiny movement of the throttle will cause the AP to squirt or at least ooze. You may think you are holding the throttle rock steady, but trust me, you are not. I've hooked up data loggers to peoples bikes and tracked the TPS output. Unless the bike is idling or WOT, it was moving, a lot in cases of rough ground.

Because of this, I rec. using the largest leak jet you can and not have a bog during normal riding.

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  • viffer vern

Posted January 05, 2010 - 06:51 PM

#10

If.... you run a small leak jet and the linkage is tightly wired together (and with an old style carb, did you do the taffy mod yet?) every tiny movement of the throttle will cause the AP to squirt or at least ooze. You may think you are holding the throttle rock steady, but trust me, you are not. I've hooked up data loggers to peoples bikes and tracked the TPS output. Unless the bike is idling or WOT, it was moving, a lot in cases of rough ground.

Because of this, I rec. using the largest leak jet you can and not have a bog during normal riding.


Thanks.


I was under the impression that only the newer MX carbs have the leak jet. I've read a lot of post on this subject and probably got a few different threads crossed in my head. I didn't do the Taffy mod but I did do the Eddie Mod so I can see how fuel is squirting at every blip of the throttle.

Speaking of squirting fuel, the duration is around 3+ seconds. I've read of others trying to get a duration of .5 or 1 sec out of their MX carbs. I thought that my setup would bog from being too rich but I went ahead and tried it anyway. It works really well, but now I'm wondering if I'm wasting fuel.

  • William1

Posted January 06, 2010 - 04:02 AM

#11

That 3 second squirt is one of the reasons for the fuel consumption rate. The taffy mod on the old slant style resolves it.

  • viffer vern

Posted January 06, 2010 - 11:24 AM

#12

Ok, thanks.

But now I'm not sure what to think. There is a post floating around here that says the taffy mod is a waste of time and to do the Eddie mod instead, which is what I did. Mill the nub off of the diaphragm, etc....

I'll research further.

  • William1

Posted January 06, 2010 - 01:03 PM

#13

Taffy mod restricts the push rod travel.
The 'Eddie Mod' of wiring the linkage together ensures a full squirt and eliminates any play. You have to shorten the rivet (or use a diaphragm with a shorter rivet ala the Honda one) to prevent binding.

The 'Eddie Mod' increases total AP run time as a side effect, you must then reduce this by the taffy mod on slant style FCRs. You need to get the squirt to the once second range.

  • viffer vern

Posted January 06, 2010 - 11:45 PM

#14

Taffy mod restricts the push rod travel.
The 'Eddie Mod' of wiring the linkage together ensures a full squirt and eliminates any play. You have to shorten the rivet (or use a diaphragm with a shorter rivet ala the Honda one) to prevent binding.

The 'Eddie Mod' increases total AP run time as a side effect, you must then reduce this by the taffy mod on slant style FCRs. You need to get the squirt to the once second range.


William,

Thanks once again for the clarification. I'm amazed that my bike runs well with out flooding out. I was just as amazed at how empty my tank was after a short ride!:moon:

OK, for all of the old style FCR (slant body) owners out there. I may be late to the party in realizing this but just in case: The Taffey mod is not a waste of time. It seems as if you should perfom this mod in addition to the Eddie mod because they address two different issues.

Maybe the mod(s) should be combined into one comprehensive mod. Should we call it the Eddie/Taffey Mod, or the Teddie Mod Maybe? Heh-Heh....

  • William1

Posted January 07, 2010 - 01:46 AM

#15

On the slant carbs, the taffy mod is of much greater importance than the wiring of the linkage. Those slant carbs all had horrifically long squirt durations where as the MX versions of the carbs all tend to be about 1 second out of the box. Key also is getting the squirt timing right.

  • viffer vern

Posted January 07, 2010 - 10:37 AM

#16

William or Eddie, can you please advise?

So I looked in to the Taffy mod on this link:

http://www.docta-zai.../whats_new.html

The text describes using a small piece of tire drilled to 3/32. However the picture shows a collar with a set screw and the rubber boot is no longer there. They also mention that this is a coast enrichmer fix. OK....

But as I was reading through the procedure the following contradiction between the Taffy and Eddie mod came into view.

On the Taffy mod the purpose is to reduce the travel of the pump linkage thereby reducing the run time of the ap, correct?

On the Eddie Mod when wiring the linkage together, one must mill the rivet on the diaphragm to allow increased travel for the linkage to avoid binding.

I'm not trying to over think this, but considering that I've already done the Eddie mod, if I do the Taffy mod won 't it be the same as not milling that rivet on the diaphragm and causing the linkage to bind or break? Or should I undo the eddie mod and do the Taffy mod instead?

  • William1

Posted January 07, 2010 - 03:23 PM

#17

Taffy mod uses a model airplane wheel collar on the AP rod to limit travel. Do a search on the Jetting forum, there are pictures there.

The cutting of the rivet does the opposite, it enables more travel.

Wiring/oring-stiffer spring on the linkage is primarily to ensure postive response, removing play from the system', the increase travel/duration is a by-product, often unwanted.
I do not wire the linkage unless I know there will be no binding. Otherwise, I use either a stiffer spring or an oring. These two provide some 'give'. Cutting the rivet like you did often adds way too much duration.

  • viffer vern

Posted January 07, 2010 - 07:13 PM

#18

Ok, Thanks a lot for that explanation.

Gotta figure out what to do next. In it's current form, riding dirt is probably not too much of a problem. However, I'm thinking about doing a 175 mile dual sport ride next month. And that could be a problem...... Maybe I'll unwire the linkage do the Taffy mod and then add the o ring.




 
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