superfastyfz450driver Posted February 26, 2010 Report Share Posted February 26, 2010 if the carb you have now was set up for a pump and you are not running one you will have issues with running the float bowls dry because the needle and seat will not flow enough fuel, if you have a gravity feed carb like say a mikuni tm 38mm with say a 3.5 needle and seat size and you rub those carbs with a fuel pump you will have issues with flooding out because the pump will put out more pressure and flow then that needle and seat can hold closed Quote Link to comment Share on other sites More sharing options...
dajogejr Posted March 29, 2010 Report Share Posted March 29, 2010 Alex... If you are going to run pumper carbs on gas without a pump, you might be able to get away with it. I personally would run a pump with pumper carbs whether it's for methanol or gas. The needle and seat, as said...is considerably smaller. While I understand someone might get a set of these to work for them without a pump, it's not something I'd chance my motor on, ESPECIALLY on alky. You need to flow twice as much fuel through the carb for methanol. You can richen up the jetting all you want, but if there's not enough fuel in the bowl, it makes no difference. I see Pumper PWKs on Ebay all the time, they are factory stock on 700 Polaris and I"m sure a few others. I've seen them go for 70 to 125 bucks. Normally they have the choke block offs. You just buy the plug for the bottom of the carb bowl and be prepared to drill out the main jet and dump tube. Quote Link to comment Share on other sites More sharing options...
Alex29573 Posted March 29, 2010 Author Report Share Posted March 29, 2010 thanks dajogejr Quote Link to comment Share on other sites More sharing options...
gmctruck1976 Posted March 30, 2010 Report Share Posted March 30, 2010 just to let you know pumper carb or not the will work if you can get boots to fit the jugs. Those carbs are not pumper carbs in the first place granted they are run by a pump on a snowmobile that is only because of where the tank sits. the nipple on the bottom is just a drain valve. the needles and jets are all the same as any other. you will still have to replace them to adjust to your engine. Pumper carb actually have a pump built into them and look very diffrent from what you have. if i can get a pick of the few i have ill post them. They dont have a float bowl to say. they are built with diaframes and plates. Quote Link to comment Share on other sites More sharing options...
dajogejr Posted March 30, 2010 Report Share Posted March 30, 2010 What we all commonly refer to as "pumper" carbs are the snowmobile 39PWK carbs that require a fuel pump. They're dirt cheap and are a favorite for the methanol burning drag race crowd. What you're talking about are the ones that have a pulse/diaphram in them, just like you see in chain saws and weedeaters... The jets are the same, but the needle and seat on a PWK pumper carb are very different than that of a gravity fed PWK. They use a pump, you are right, because of the location of the gas tank not being directly above it. That being said, they have a much smaller needle and seat...or else the pressure from the fuel pump would overflow and flood the carbs. You're talking apples, we're talking oranges! Quote Link to comment Share on other sites More sharing options...
STINKYDELUXE Posted March 30, 2010 Report Share Posted March 30, 2010 I ran pumpers on my 521 with big bowls for a season with no problems. Quote Link to comment Share on other sites More sharing options...
Alex29573 Posted March 30, 2010 Author Report Share Posted March 30, 2010 what type of racing did you do? Quote Link to comment Share on other sites More sharing options...
dajogejr Posted March 30, 2010 Report Share Posted March 30, 2010 300 ft when I raced with him...sand drags. At Ionia and Bob's Quote Link to comment Share on other sites More sharing options...
STINKYDELUXE Posted March 30, 2010 Report Share Posted March 30, 2010 what type of racing did you do? just dunning and ripping up my back yard. I run a pump now but only because they are supposed to have one. I didn't notice any difference when I added it. Quote Link to comment Share on other sites More sharing options...
STINKYDELUXE Posted March 30, 2010 Report Share Posted March 30, 2010 300 ft when I raced with him...sand drags. At Ionia and Bob's I bought the pump about half way through the year. Quote Link to comment Share on other sites More sharing options...
Alex29573 Posted April 2, 2010 Author Report Share Posted April 2, 2010 dajogejr, so i have gravity feed 35PWKs now and let's say i want to convert them to alcohol... Since my 35PWKs have the large needle/seat, how would you get them to seal right when i convert to alcohol and run a pump? 1 Quote Link to comment Share on other sites More sharing options...
Blewbyu Posted April 2, 2010 Report Share Posted April 2, 2010 dajogejr, so i have gravity feed 35PWKs now and let's say i want to convert them to alcohol... Since my 35PWKs have the large needle/seat, how would you get them to seal right when i convert to alcohol and run a pump? If your carbs arent setup for a pump, doesnt mean you need one just to switch to alcohol. You just need to drill out your dump tube and main jet. Depending on the size of your motor and riding, powerjets and billet bowls also. Its not something anyone can do, id look into a sponsor/builder. Or someone who has done it successfully before. Quote Link to comment Share on other sites More sharing options...
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