Gray I need your advice on ZIP Ty MOD

7 replies to this topic
  • Raider23

Posted January 08, 2010 - 01:07 PM



I have an 09 450 and have a slight hesitation with the throttle as well as some backfire at low to mid range throttle position. I did a search on both the R&D Powerbowl and the Zip Ty carb mod and it seems like all of the threads were about older bikes. Meaning 05-07 models. What is your take on these mods for my 09?
Thanks for your time

  • grayracer513

Posted January 08, 2010 - 01:57 PM


Two things will get rid of your bog without dumping money into it: Proper jetting, and proper riding technique.

The first speaks for itself, and one of the things with jetting an FCR-MX that gets overlooked a lot is the effect of using a needle with a smaller upper diameter to boost the off-idle response. If your bike is backfiring at a steady mid throttle condition, it sounds lean, and I would look at your pilot setting, then possibly raise the needle a little.

For the most part, I don't think any of this kind of mod is really needed on an '09. You can, if you like, use the stiffer Merge Racing AP linkage spring, but the '09 spring is already stiffer than previous years (though not as stiff as the Merge). Then you can tune the AP through selecting diaphragms and leak jets. Just remember that not every hesitation is caused by an inadequate output from the A-Pump.

Motorcycles, big 4-stroke singles included NEVER had accelerator pumps when I learned to ride, nor did they start to appear until around the later nineties sometime. Everyone who wanted quick response from their thumper or big twin had to learn to "roll" the throttle instead of snapping it open. Diaphragm carbs (the "Solex" type, with the big vacuum diaphragm on top) do this for you. You open the throttle, but the slide will only rise as fast as the incoming air velocity will raise it, so the air flow velocity through the carb stays high enough to keep fuel flowing. With the "rolling" technique, you do the same thing manually.

In slo-mo, you would be able to see my right hand move slowly at first, but you would also see that I am twisting the throttle open faster as it opens farther, and as the engine responds. In real time, it sounds like the engine exploded from idle to 5 or 8 grand nearly instantly. This takes very little time to learn, and once you've got it, you do it without thinking, and you won't need any of the widgets.

Obviously, there really is such a thing as an engine that truly doe not respond to the throttle as well as it should, and in that case, corrections really should be made where the problem is. But many times I've had people tell me they have a bad stumble, and when I ride their bike, I can't see the problem. Likewise, I've had a couple of people who rode mine complain that it bogs. Maybe, but not for me or for my son. :moon:

  • davbrucas

Posted January 08, 2010 - 05:15 PM


I have an 09 as well and the diaphragm is already the low profile one, so all you need to do is adjust the AP timing and either add the merge racing spring..or do as I did and throw an oring on the linkage. I had to turn the AP screw about a full turn CCW to get the squirt correct. As far as the backfire/hesitation I would raise the needle (or change it) and riched the fuel gray stated.
And roll on the throttle instead of stabbing for better throttle response.

  • Ga426owner

Posted January 08, 2010 - 05:21 PM


I am not Grey, although I have some Grey....:cheers:

I did this ZipTy mod to several bikes and it is worth it...but you have to have the jetting perfect to see the benefit as Grey indicates, otherwise zero benefit and sometime worse than prior results if the jetting is off or the acell pump duration/squirt is not exact

I am torn on the PowerBowl....I know some that swear by it some that do not...until they give me one to test I am not forking out the money for one.....I forked out way too much already to test gizmos......and have a box full of gizmos that collect dust....:moon:

If you are not the type to tinker and just want to ride wash and relax.....forget about all this gee wiz techno crap
otherwise you will compound the issues and get frustrated and bash the products like so many have already....there is a tuning factor to all of it. You either like to tune and ride or you don' decide

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  • ectm3

Posted January 14, 2010 - 12:38 AM


:ride:Try a #45 pilot,switch out the needle to a NFPR 3rd clip,a #165 main jet,and about 1 1/2 turns on the fuel screw(may require some tweaking).I run this set-up on my yz450f 2009 and the popping is gone.

  • dvn

Posted January 14, 2010 - 04:00 AM


:ride:Try a #45 pilot,switch out the needle to a NFPR 3rd clip,a #165 main jet,and about 1 1/2 turns on the fuel screw(may require some tweaking).I run this set-up on my yz450f 2009 and the popping is gone.

Isn't a 45 pilot stock? I am running a 48 with 165 main and just ordered the nfpr needle.

  • ectm3

Posted January 15, 2010 - 09:35 AM


If you run into hard starting,id go back to the #45 pilot.

  • joethunder

Posted February 19, 2010 - 07:42 PM


I have an 08 450 and it has a slight hesitation when rolling it on. Runs great once it is off the bottom. Have not really thought about it to much, until I was at the track the other day. There was kx 250f that sounded really crisp and clean. Big difference between the way my bike sounds and the kx. May need to improve my jetting skills.

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