Hey Fella's-

I was reading about the Edelbrock Quick silver Carb- and here's what it features:

-No altitude effects on air/fuel mixture
-No flooding on a roll-over
-Won't bog under extreme conditions -(hard landings)

1. Does anyone own this carb- and is all this true?

2. They call this a "Pump" type carborator.... what does this mean?

3. When should I upgrade to this carb?.... after I bore my machine to a 440?

Thanks for your thoughts...

 

I have had mine on for only a short time now (I'll give it a good workout over the holiday weekend), but my first impressions are very favorable!! The "pumper" designation is because it has an accelerator pump. When you hit the throtle, there is a squirt of fuel into the carburator (rather than just relying on the vacume created by the flowing air to suck fuel from the bowl), this gives better low end response. I would do the carb. before doing the 440. You might decide you don't need the 440!!

The best thing is the adjustability of the carb. There are NO JETS TO CHANGE!!! Tuning on the low end is done by adjusting the needle up or down (with a screwdriver) or changing the needle for mid to high end. The whole principle of the carb just makes way more sense than the archaic method of changing jets.

Do a search of both Edelbrock and Quicksilver, and you will find a whole bunch of comments.

 

Thanks for the reply- it was helpful-

however, I thought the stock carb on the 400ex uses the "squirt" method as well. I was able to take my choke plate out of the carb and use the ole' pump the throttle 3 times to get it to start trick. Every time you hit the throttle- fuel gets squirted into the carb.

I could be mistaking this for something else- any ideas anyone?

Also- I need a serious power increase- and I know the Carb upgrade will only increase throttle response and yes- no need to change jets. You can't subsitute raw power of the piston unless you replace it.

Thanks for replying-

Brian

 

This is just my .02. The cost of a quicksilver carb is very comparable to that of a keihin FCR. Both are going to run you right at 400.00. (For those whom would like to know, I just got a 39mm FCR from Trinity racing for 399.00)
They both have a pumper system and other comparable features. The things that sold me on the FCR were that keihin has been making carbs for bikes alot longer than edelbrock. Being an Engineer myself, I can understand the realities of a learning curve. NOBODY ever releases a perfect product the first time.

Also, the FCR is the only carb around that uses a slide system that rides on bearings. That means smoother actuation and less of a chance of throttle stick.

Only an oppinion, take it or leave it.

 

I just got my FCR and I have to say....I don't complain about more adjustability! I'd rather have 3 circuts to tune than one. Just my opinion. Email me @jcv400ex@hotmail.com if you want to get a FCR carb. I can hook you up....

 

we have tested both carbs on the dyno the fcr39 is the best carb for the 400ex with motor mods .....a modifed stock carb is the best for woods type racing the fcr is better for mid and top inprovments .....

 

how can i modifiy the stock carb?

 

you need to have it taperbored

 

correct me if i am wrong biggy( or anyone else) but is taperboring the stock carb is making it larger from the air filter end of the carb and tapering down near the throttle valve so it can still cut off air flow to make it idle right?

 

yes your corect they jig it and bore it to make it larger then polish it .that makes it capable of flowing more air . the stock carb will not flow good enuf to handle a modified 400ex you can opt to buy a fcr39mm carb but you sacrafice some bottom end ....good carb for racing ......