Wondering if anyone knows why most of the KZ engines seem to use the round Mikuni fuel pump with the two outlets? The Rok shifter I’m used to uses the dellorto pump, and wondering if that will feed a KZ well enough or I should get the Mikuni one for my KZ.
Dellorto pump will be fine on the KZ.
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I figured as much, but even the Vortex KZ’s seem to use the Mikuni so figured I’d see if anyone had any experience with both and pros and cons.
The round Mikuni is cheaper and also easier to rebuild. Those smaller parts on the Dellorto are a bitch to replace.
TM typicalky fits the Mikuni on the their KZ line.
But for reasons unknown to me, they outfit the KZ10 ES series with the Del Orto. Go figure. The isolator bracket the Del Orto is mounted to also holds the ignition box, so everything associated with the engine is with it, which is nice from a packaging perspective, & being rubber isolated, vibration to the unit is dampened, so there’s that.
I actually didn’t like the pump orientation on the bracket, so I made an interface to rotate it 90 degrees to make the routing of all the pulse pump & fuel lines slightly more direct & shorter.
Reviving an old thread. Can someone school me on pump selection and why there are so many Y connections. Are the KZ fuel pumps not internally regulated/bypass?
I’m just use to the single outlet Mikuni and now Dellorto since Rotax has recently switched to those for the Rotax. No need for return line.
Depends on the pump, the old round mikuni you have to run a bypass line on or it will overcome the floats. The dellorto is internally regulated and does not need one, and the newer mikuni is also self regulated. Each setup works, but just requires adjusting jetting to suit. Very similar to the float setup for the dellorto carb, where some prefer the one piece floats attached to the arm and some prefer the individual floats which are separate from the fulcrum arm.
I guess I would rather run less fuel lines and less connections with the Dellorto or Mikuni w/ the bypass. Initial cost on the Mikuni seems higher with cheaper rebuild kits. But my fuel pumps have been mostly bullet-proof if you constantly drain the fuel, and I rebuild them every six months or so anyways for peace of mind.
This just looks like a mess with too many failure points. Y into a Y? Why is there two outputs just Y’ed together? Also is the little heat sink looking thing just a small reservoir? Surely, it’s not trying to cool down the fuel.
I definitely prefer the dellorto setup as it is a cleaner install. The only benefit of having a return line in my opinion is IF you have the return line valve you can somewhat alter the tuning on track by closing or opening the return valve. I used to run one at one time, but haven’t in years. These days I run the dellorto pump, and the individual floats in the carb.
I’ll have the carb apart today to give it a good once over and see what I’m working with.
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The old twin outlet Mikuni has two outlets for redundancy. The Y joins the two outlets into one, which feeds the main line into the carb. The other Y splits to the recovery line that goes back to the tank. It is required as the output of the pump is greater than what the carb needs.
The reservoir is there to store excess fuel to cope with fast closed to WOT situations, should the pump feed not be enough for a split second.
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