custom derbi intake and new carb

02Sep09

after kitting and piping the derbi (65 pyramid reed metra and 75cc zen pipe) i tried running it with the carb and intake i already had, a 15mm sha and the stock intake dremeled out to 14.5. it really sucked, and was obvious i needed MOAR CARBURATION.  so i ordered an 18vm mikuni. it’s an awesome carb, takes dellorto jets, easy to access screw adjustments, good build quality.

only problem i had was figuring out an intake for it. i was going to have nate help me weld one up at the garage, but before i went and bought aluminum stock he had an idea. there was a 19mm express intake he got in a box of stuff from IRE (pretty sure it was made by IRE Rick) that had enough room to drill holes for the derbi bolt pattern.

stock intake on the left, express made derbi intake on the right

the intake as is didn’t leave enough room for any carb mounting options…

so we chopped the top off and attached some radiator hose instead…

then turned the mikuni from a clamp on style to spigot mount…

and everything mounted together quite nicely.

i’m in the middle of tuning my variator (more on that later) and some more jetting. this bike is getting close to being a blaster!

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2 Responses to “custom derbi intake and new carb”

  1. 1 Jeff

    You showed one shot of the side of the carb, and the 2 adjusting screws were almost identical to my stock, but your slightly larger screw on mine has a plastic knob as if to adjust on the fly, and then the other screw needs a lil stubby. I can’t get something right, mine’s a 2stroke and i can get it at best to have a little poer on takeoff and be fine till i hit just before wide open and it’s not getting enough of something? it won’t go any faster and just feels held back. I just put the Technigas Next R Exhaust and tighter clutch springs and it came with lighter vari weights. Anyhelp would be greatful, Thanks, Jeff

  2. 2 gabeb

    jeff, could be you’re running a little lean or rich on your needle or pilot jet. unfortunately my derbi has been on the back burner for most of this year, so i haven’t been running/tuning it at all. mine was a bit sluggish off the line as well, but i had stock clutch springs so i always attributed it to that. if you’re getting good revs before the clutch engages and then it’s still bogging out i’d check into those two things on the carb, and make sure your vario isn’t throwing out too early. hope that helps.


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