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yz157

Quickshot 3 question

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I just bought a Boyeson quickshot 3 and installed it last night. Went to start the bike and after 2 kick it started leaking fuel out of the drain lines from the carb. I didn't look into it any further because it was so late but I am baffled by this. Anyone know what is going on with this?

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It's flooding. While installing the pump cover, you have apparently gotten the float assembly wrong somehow, or possibly the float needle has something small under it.

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ok i'll tear it down again tonight and see whats going on. Thanks for the help. Have you ever used on of these?

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currently have one on my 2002 crf450 with 488 big bore, high comp piston, hot cam, hot rod crank, its a trick little part but.......once its set its just a shiny nice little piece of billet.

are you familiar with the accel pump and leak jets on FCR carbs ?

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No I'm not. I did get it to run without flooding last night. Certainly cut out alot of hesitation and bog at low rpms. I haven't really played with it yet but i'm gonna do some fine tuning tonight? why is it just a peice of billet on there after it's on? lol

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The adjustable leak jet assembly on the quickshot 3 is just a skrew similar to your pilot air skrew allowing a larger of smaller orfice. this orfice allows more or less fuel to leak out of the accel pump circut and back into the float bowl. thus adjusting the squirt duration ( partially) and volume. so when you find the sweet spot where ample fuel is allowed to be injected without bogging or hesitation the adjuster skrew doesnt need to be moved, hense just a shiny piece of billet and good convo starter, does do its job tho, full accel pump chambers ( without noticable air pockets ) and great adjustabliy of the leak jet, some say spend 8 bucks and buy the one smaller leak jet and most guys find thats enough. i reccommend starting with the adjuster at the stock leak jet setting and moving one jet size either way ( turning the skrew in or out) test for a bog or hesitation. make notes about how many turns and perfromance. also ensure the linkage is setup to spec. no sense adjusting, if the whole system isnt setup correctly, look into the o ring mod if you havnt already.

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Based on my experience, the only advantages to be had from the QS3, or any other such aftermarket pump cover, is the improved performance that the slightly better check valves in the QS3 sometimes provide. The check valves in the OEM pump cover can occasionally fail to seat immediately when called on, but not that often. Other than that, there is the convenience of being able to adjust the leak jet from outside, but once the leak jet orifice is trimmed to your liking, it will never need to be reset unless the egine is fundamentally altered with a new set of cams or something.

Anything that can be done with the Quickshot can be done with OEM Keihin parts just as well, and the pump is not necessarily the right component to look at when chasing a bog or stumble. Pretty, yes. Convenient, for a while. IMO, money's better spent elsewhere.

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The O-ring mod: http://www.thumperta...233#post6157233

It's about 3 notches better than the wiring mod on a scale of "caveman" solutions. The real issue is that the accelerator pump linkage separator spring, which is there to allow the accelerator pump diaphragm to bottom out before the throttle is completely opened, is thought by some to be a little bit on the soft side in earlier 450's, which can limit the force of the pump squirt. The wiring mod locks the linkage together, so a bunch of even more gorilla-like things have to be done to the pump to make it all work. The best solution, if you really see this as a problem, is to use a stiffer separator spring, such as those offered by Merge Racing.

The O-ring mod is kind of an in between approach. It stiffens the separation spring by adding to the tension holding the driving and driven segments to each other, but leaves it flexible/compressible so it can continue to work as designed.

Frankly, if you tune the carb correctly otherwise, and perhaps adjust your throttle twisting style a little, none of this is necessary.

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Well that does look simple but are there any issues that can be caused by doing this o-ring mod? If not, I would think everyone would be doin this to their 4 strokes. I know I will if there is nothing to lose...

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Yes, sometimes. The O-ring will eventually break, for one, and I know of at least once where that caused a sticking throttle condition. For another, the resulting pump shot is often more than the engine wants, and it ends up running worse.

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Based on my experience, the only advantages to be had from the QS3, or any other such aftermarket pump cover, is the improved performance that the slightly better check valves in the QS3 sometimes provide. The check valves in the OEM pump cover can occasionally fail to seat immediately when called on, but not that often. Other than that, there is the convenience of being able to adjust the leak jet from outside, but once the leak jet orifice is trimmed to your liking, it will never need to be reset unless the egine is fundamentally altered with a new set of cams or something.

Anything that can be done with the Quickshot can be done with OEM Keihin parts just as well, and the pump is not necessarily the right component to look at when chasing a bog or stumble. Pretty, yes. Convenient, for a while. IMO, money's better spent elsewhere.

exactly!!!!!

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