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yzf 426 Edelbrock carb???

By solarRMS,
in YZ400F/426F/450F/450FX

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solarRMS

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Ok im a new member im a 30 and over vet been racing 2 strokes my whole career finally went to a thumper after riding all my buddies thumpers im getting older and these bikes are easier to ride, i didn't want to spend much at first so i purchased a 2000 426, very clean, new top end with pro curcuit suspension the handling of this bike is amazing all my bikes have had suspension but this bike is unbelievable this bike turns as easy as a 125 no joke. my question is this dang carb if i pin it too fast it will hickup i went down during practice on a step on step off because of this hickup i've done everything i know to do with basic carb knowledge from racing all these years nothing works, this bike was manufactured in dec 99 i've heard this is a known problem so i did some research and found out Edelbrock makes a carb for this bike for 400 dollars does anybody know about this carb if so is it worth the money and how good is it, unless there is a trick to this OEM carb i dont know about but if this Edelbrock is as good as they say i would rather use it for the power increase the 426 is very strong but i could use all i can get. last thing this bike has a canada seal of transportation with the # 506 in the middle of the canadian leaf, the sticker is just bellow the vin sticker anybody know what this means. sorry for the long post never had to ask for help before 2 strokes are pretty strait forward i'am having fun learning about 4 strokes this forum is very helpful thank you for your help!

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Grand Master

grayracer513

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Actually, this is fairly normal. You can do a couple of things to reduce it, possibly eliminate it, but don't expect to entirely get rid of it. Big four-stroke singles have very poor intake vacuum at an idle compared to two-strokes, and by snapping the throttle open, you are eliminating what little it has and expecting the gas to get itself out of the float bowl and into the carb without any help from the engine. If the throttle is opened even just a little more slowly, the idle circuit is set up to transition the fuel flow to the main circuit, and things continue to work. The carb has an accelerator pump built into it to help cover this "hole" in the fuel delivery by forcibly spraying a shot of fuel into the intake in the hope that it will be enough to keep the engine running until the transition takes place.

The second thing is to learn how to "roll" the throttle progressively. Learn to open the throttle a little more slowly just off idle, opening faster as the engine responds. You'll catch onto it quickly, and you'll find you don't have to take much off the snap to get it to work, and that the engine will respond quite quickly enough for you. The fact is that if you need a sudden burst of power from a 426 that's running right, just a quick quarter throttle is often all you immediately need, and you can roll in the rest as you're arms get stretched.

Even so, there are things that can be done. Be sure your pilot jet is the right size, and the pilot screw adjustment is correct:

https://www.thumpertalk.com/forum/showthread.php?t=327405

...then you can also try the BK Mod:

http://motoman393.thumpertalk.com/tech/carb.html

Personally, I don't recommend the Edelbrock carb for a YZF.

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Speedracer747-400

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I would send the carb to Zip Ty Racing for $100 before dumping $400 on a Edelbrock carb that won't compare to a properly setup Keihin FCR carb.

Zip Ty Racing

http://www.ziptyracing.com/products/product_detail.aspx?id=MTUxOQ==

ZipTy Racing Carb Modification - test

https://www.thumpertalk.com/forum/showthread.php?t=458476

Here's a few things you can also try to get ride of the hickup when you pin the throttle to fast. You will need to adjust the AP(accelerator pump) circuit. The AP squirt duration can be shortened by using a diaphragm with a longer length rivet. Another option is the BK mod which will make the AP squirt duration adjustable. Most people find around a 1 second squirt duration works well. Make sure to adjust the AP timing screw so that it starts to squirt when the slide just starts to open, but doesn't hit the slide. The AP squirt pressure can also be increased by installing a stiffer AP linkage spring or doing the 0-ring mod.

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Apprentice

solarRMS

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thank you 2 for the advice i will do this tricks and see how it works but even a little hickup is not exceptable all the other 450s i've riden never had this problem and i dont really want to change my throttle control to adapt to a bad designed carb. Im still courious about the Edelbrock does anybody know about this carb!

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Grand Master

sirthumpalot

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A buddy got the eddlebrock for his YZ and loved it, search the messages here and you'll see the posts. It was a few years ago, I think the user name was yzfan but I'm not positive. I've got an 01' 426 and never had this problem myself so it's definitely possible to get things tuned right, maybe figure out what the differences are between the 00' and 01' and make those changes as a baseline. I'm not sure if the 00' and 01' had the same carb or not, but hopefully the carbs are the same except for settings. Boyensen makes an accelerator pump plate that is said to improve things as well, maybe do some research and see what other 00' 426 owners who have tried this part think about it. The BK mod and ZipTy service referenced above also seems to get rave reviews from all who have tried them.

That said, in my own personal experience whacking it open on these things will wear you out quick! Or at least wears me out quick. I'm much faster and can ride much longer when I'm more controlled with the right hand. Don't kick it until you've tried it, and good luck!

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Rookie

blank999

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I used a edelbrock carb on my 2001 426. It does add a bit of horsepower. Was great at the dunes. But the carb doesn't have a choke or a hot start. Was very difficult to start when it was cold outside. And even worse on a hot day when you stall it!!!!!:excuseme: I now have the original carb with the BK mod and the bike is super responsive. And now my edelbrock is a pretty paper weight. :confused:

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Proficient

harwood39

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ok, i have searched and searched. I have the BK mod already done on my 426, but what is this o-ring mod... i cant find how to do it anywhere. i have a little bog in this 40 degree weather coming off idle, but im guessing its due to the jetting in this weather.

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pbviking

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I called Zip Ty Racing soon as i got home today i'am very excited, sending my carb to them this week. Thank you all very much. I will post results on carb work, and on grayracers advice!

Did Zip Ty correct the carb and get the bike running properly? I have the same problem with the bog :ride:

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mkporn

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I called Zip Ty Racing soon as i got home today i'am very excited, sending my carb to them this week. Thank you all very much. I will post results on carb work, and on grayracers advice!

Did you even try a little tuning on the carb first? Might be able to save yourself 1 $100, shipping and the down time and you will learn a bit about the carb......Just a thought, I am a cheap bastard and would rather try to figure it out on my own for a little time investment than send my money off to someone else.....

To each his own.

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mkporn

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it is a o-ring that is used to hold the AP actuating arm to the throttle actuator.... If you pull the little black cover off the carb where the throttle cables are, you will see a plastic piece and with a little angle on the side. if you roll the throttle on quickly and watch this piece you will see a seperation between it and the metal peice of the throttle. The o-ring acts like a mechanical fastener with a bit of give at this point and is simply slipped over the 2 pieces to make them act together and does not allow the delay of the AP actuator.

The o-ring needs to be small enough to stay on both pieces and act as a link between them....

It would make more sense if I had a picture or a drawing.....

Anyone out there able to give him a pic?

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Grand Master

grayracer513

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it is a o-ring that is used to hold the AP actuating arm to the throttle actuator....

Something to bear in mind about the O-ring and other similar mods in this case is that the OP has a 426. The 426 bogs because the duration of the pump squirt is too long, not because it needs a stronger shot. To correct this, 426 owners should first try the BK Mod instead. After that, if there's still an issue, one could proceed with other corrections.

The O-ring mod or the Merge spring are beneficial to 450's, but should be used on those equipped with AP leak jets only.

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pbviking

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After that, if there's still an issue, one could proceed with other corrections.

QUOTE]

What other corrections are there? I have done the BK mod and the bike still has bog

air screw is 1 1/4 out per manual

main 60

needle is 1 notch lean

riding at 6K evevation

Its such a pain in the butt to remove the carb and put it back on each time then to find out the bike still has bog:banghead:

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dmoney1074

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Something to bear in mind about the O-ring and other similar mods in this case is that the OP has a 426. The 426 bogs because the duration of the pump squirt is too long, not because it needs a stronger shot. To correct this, 426 owners should first try the BK Mod instead. After that, if there's still an issue, one could proceed with other corrections.

The O-ring mod or the Merge spring are beneficial to 450's, but should be used on those equipped with AP leak jets only.

Burned told me to do it on my 426 :ride:?? and it worked! But I agree that JD jet kit is the best mod I ever did to my old 426...

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