Help with Dialing in the Edelbrock Carburetor

6 replies to this topic
  • DualSport650

Posted September 16, 2005 - 10:49 PM


TT BRP Riders,

Hey, I have a quick question from you Edelbrock gurus on dialing my Edelbrock in perfectly. I have 2 areas where I want to dial in my carb better...

1) Starting/Idling when cold
When I start the bike when it's stone cold, I can get it to light on the first kick... but it then quickly dies like it's starving for fuel. It won't get to an idle the first couple/few times I get it to fire up. This happens even when I turn up the idle knob way up too. After I get it going and it warms up, it starts easily after that, even if I dump it. Anyone know how to dial that in better?

2) Idle to 1/4 throttle response
When the bike is warmed up and I'm riding it, it seems like in the low RPM's could use a little more gas (accelerator pump). It revs out real nice, but I notice the lower RPM's could use a little more go juice because there's a little to be desired. I got the Edelbrock Adjustment info from Qadsan's old post (see below), but which way do I turn the screw on the SIDE of the carb to give more gas (accelerator pump)? Clockwise, or counter-clockwise?

I'm getting just a little popping on deceleration (barely), so I'm going to turn the knob on top a few clicks to the RIGHT to richen it up a bit.



Edelbrock Adjustment

1) Adjust for the first 1/8th - 1/4 of throttle from full no throttle. With the bike running (you might have to have the tank loosened up and just sitting on the bike...) Whack your throttle fast on from a warmed up idle. Adjust the little screw on the side of the carb – that’s your pumper adjust. Adjust until there is NO hesitation at all. To much or to little pump squirt will make for a slight hiccup or slight hesitation. Keep whacking it and turning the screw until you get it right. You will know when its there...

2) Adjust for 1/4 to full throttle. go ride the bike--with it warmed up ride it hard--hold it open in a lower gear for a bit longer than normal--if it pops on de-acceleration you are too lean. Go back to the truck-with the engine off-reach up to the red knob on top of the carb - and with the throttle held steady wide open-turn the knob - right for rich, left for lean. Often its right on from the factory - but if you are experiencing popping when you go suddenly off the gas - that’s what’s up...its lean - go rich. If you are to rich you will get poor mileage and eventually carbon will build the bike will be harder to start.

3) Once you get your needle tuned for the best performance from ~1/3 to WOT, work on tuning the accelerator pump. Once you find the 'range' where you're getting the best off idle throttle response, work on fine tuning within that range in 1/8 turn increments until your initial throttle response is razor sharp. I find it easiest to tune on hardback (dry lake bed, road, etc) where you can better feel the changes because of better hookup. Initial throttle response from quick blips should be much sharper, more pronounced and instant once the pump is properly tuned. Instantly lofting the front end on trails should be easier than ever. I still like my Edelbrocks

  • Ramcc4x4

Posted September 17, 2005 - 05:31 AM


Turning the screw to the right richens the accelerator pump, turning the screw to the left decreases the pump shot.

  • frankstr

Posted September 17, 2005 - 05:53 AM


I turn my idle up a turn when starting cold and she never dies, starts first or sec. kick........ :banghead: ... :applause:

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  • qadsan

Posted September 17, 2005 - 07:17 AM


If your bike isn't staying lit AND performance is lacking from idle to 1/4 throttle, then I'd suspect too weak of pump shot. Find out where your pump screw is set and then make adjustments. As Ramcc4x4 said, right = more pump and left = less pump. If your performance was good from idle to 1/4 throttle, but the bike was difficult to start, then I'd say give it another pump or two from the throttle, but the addition of the performance issue leads me to beleive there 'might' not be enough pump shot.

When the engine is cold, it's more difficult for the fuel to atmoize and the fuel sticks to the cylinder walls which is why the engine won't start as easily or will stall out periodically when cold. When the choke lever on the stock carb is engaged, a valve at the mouth of the carb partially blocks off "Chokes" the incoming air, which causes the vacuum inside the carb to increase, thus drawing more fuel into the venturi from the fuel bowl. It's the enriched mixture that's the key to starting a cold engine and fully twisting the throttle quickly a couple times to make the accelerator pump on the Edelbrock squirt more fuel into the venturi also temporarily enriches the mixture.

  • DualSport650

Posted September 17, 2005 - 08:45 AM


Alright dudes. Thanks for the info.

I use plenty of accelerator pump when I start the bike up from cold.

Here's how I do it...

1) Turn the gas on at the petcock and turn up the idle knob
2) "Charge" the cylinder by grabbing full throttle 3-5 times and kicking the bike over about 10 kicks
3) Give it a BIG swift kick

It usually fires up on the first kick this way, but dies about 3 seconds later so I have to give it about 3 of these BIG swift kicks.

Sounds like I need to turn up the accelerator pump quite a bit!!! :banghead:

  • RdrMtn

Posted September 17, 2005 - 10:23 AM


If I may, I have an edelbrock question of my own. I need to dial in my 0-1/8 throttle settings. When cruising down a street, using practically no throttle, the bike does'nt run smoothly. It kind of jerks around erratically. How can i make it run smooth at almost no throttle opening? It runs fine at all other throttle openings.

  • bork

Posted September 17, 2005 - 08:27 PM


Mine jerks too , I dont like it . It seems to do it when too rich but performance response seems to be better there. And of coarse, I run out of gas earlier. If I lean out it tends to reduce almost all of jerk but then power seems sluggish . I personally think needle curv grind could be better . I've been tempted to put on dyno to prove this by adjusting lean and then rich and see where dyno curve ends up . my .02

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