Suzuki Quadracer HQ
Suzuki Quadracer HQ Discussion => Suzuki Quadracer HQ - General Discussion => Topic started by: Kreidy818 on April 15, 2014, 06:26:56 pm
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Another thing to consider with a PSI carb is good luck getting support if you need some technical advice or parts/metering rods,etc.PSI support was terrible for years,highly doubt its changed.
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Everytime I scroll down and see Motorgeeks name I know I'm about to be in for a world of knowledge lol.
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Ok guess I will stick with the PWK. If anybody is looking for a PSI there is someone selling one for $250 with a filter at Albany NY craigslist.
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i ALMOST had my hands on one late last year but got sniped on the bid. They SOUND like they will work well,,, being as its basically 3 power jets, one for each area of throttle,,,, but they are too expensive new to buy and play with. If you get one,,, let us know how it does
Power jets tend to dribble and cause inconsistent fuel delivery at low air velocities. Power jet discharge tubes are placed at different places in the air stream so that they will discharge fuel when the air velocity in that portion of the cross-section is high enough to pull fuel through the discharge tube into the air stream.
I have watched conventional power jets operate at part throttle on the dyno. At small throttle openings when there is not any air velocity passing over the power jet discharge tube, there is not any fuel flow. As the throttle is slowly opened, the discharge tube will start to drip. As the throttle is further opened the discharge tube starts to drip must faster. When the throttle is opened sufficiently to produce high velocity over the discharge tube the fuel looks like a spray. During this transition from drip to dribble to spray the engine is not getting the same fueling every engine revolution and results in a ragged mixture and a misfire can often be heard.
If the jetting in the currently operating circuit is a little lean and is counting on the power jet to provide the ideal mixture, the overall mixture is correct during a drip and lean between drips.
Another problem we have had with power jet carbs is the power jet will stop flowing fuel to the air stream when the bike hits a chuck hole or lands off of a jump or any situation that is producing sufficient "G" loads. In a conventional carb the distance from the fuel level to the point where the fuel is discharged into the air stream is usually no more than 5 to 8 mm. In a power jet carb this distance is usually at least 25mm. This distance the fuel has to be lifted to the air stream slows the response for fuel to start flowing and makes this column of fuel more sensitive to small "G" forces that will stop the fuel flow.
Hook up your go pro camera so that it can watch the clear fuel line feeding the power jet and ride the bike through a section of "choppy" terrain at full throttle and watch what happens to the fuel feeding the power jet.
My experience has shown me that carbs equipped with any type of power jet that is not electronically controlled or is NOT used on terrain that is somewhat smooth or is NOT used on motocross bikes that have vastly superior suspension, will not provide very precise fuel mixture to the engine.
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Yikes over $1000 for 2 stroke carb, better have lips for full service! Ill stay with OEM carb or PWK
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i ALMOST had my hands on one late last year but got sniped on the bid. They SOUND like they will work well,,, being as its basically 3 power jets, one for each area of throttle,,,, but they are too expensive new to buy and play with. If you get one,,, let us know how it does
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Anyone ever use a PSI big air carb. Thinking about buying one.