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Post by matlock on Aug 16, 2019 21:17:50 GMT -5
now i cant figure out my throttle when irev it up slowly its fine but if i gun it it hesistates like its sucking in air firstn thebn revs and when at max throttle if i let off then hit it full again it hesitates a few seconds like silence then starts revving since i switch the open pod filter for the stock air box some reason the open cone filter stopped working so well it wouldnt goto full throttle without bogging when the day before it worked fine thats why i put stock box back on but im puzzled
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Post by repherence2 on Aug 17, 2019 0:50:36 GMT -5
air leak somewhere?
if not, you probably need to clean up the tune on the carb. sounds like it's needle/jet related. have you tried different needle clip positions? like moving the clip from #3 to #4 groove, test. move clip from #4 groove down and test. and so on, test at #1 groove and test at #5 groove. whichever way you end up on the needle position, will tell you if you need to go up or down on the main jet. if you get the clip all the way up on the needle, you probably should down jet by 2 and test with needle at mid position. if you get the clip all the way down on the needle, you probably need to go up on the main jet by 2 and retest with needle in mid position. in either situation, you going retest the needle clip at all 5 grooves to find the setting that gives you the desired result.
it all depends on your tuning approach. I keep it simple by starting with the air mixture screw. what it takes to get it started and idling involves your air mixture screw and the pilot jet. if you close to zero turns out to get it to idle, you need to change the pilot. if you are near 3 turns out on the air mixture screw, you need to change the pilot. so me carbs depending on the set up you might have to try different emulsion tube, where the main jet screws into on the OKO carbs.
it was recommended to me to tune the idle first. that involves the idle screw and air mixture screw. it's a balancing act there. if you need to screw the idle screw so far in that it is almost maxed out, you probably need to change the pilot jet. after I sort out the idle and pilot, I tune for WOT to get the proper main jet. I simply use temperature to tune the main jet. I tune for Wide Open Throttle to make sure I can maintain full throttle for days without overheating, ever. as a disclaimer I use Jog90/Polaris cooling fans on my 70cc motor and my 94cc motor.
no matter which block I have on the bike, carb main jet tuning process is the same. I tune for WOT at 350° F. I have approached 380° F on long inclines. if tuned that way, you can hold WOT all day long and not overheat. I tune that way for longevity/reliability. the last thing I tune is the needle position. after the initial main jet tune, needle clip position dictates your direction for the main jet. if you are at #1 or #5, you probably should change the main jet.
too keep it simple, I don't fiddle with different needles. I only mess with main and pilot jets, and if necessary I mess with the emulsion tube.
your approach to tuning will determine how detailed you get with the carb tuning. here on oahu, I run the same carb setup as the fast elites/dd50s. CT intake manifold, 28mm OKO carb, no filter, velocity stack/bellmouth. I smooth out the 0-50% throttle with a venturi diffuser. whether it's a 28mm OKO open filter or a Polini CP 24mm with air box, the tuning approach is the same for me.
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Post by harleyracer59 on Aug 17, 2019 2:13:14 GMT -5
is the pod filter still dry? ive had issues when they get oily or gas soaked from carb spit back riding the night before. if theyre dry, then I agree with repherence2. I made an intake defuser out of half a spray can lid. then trimmed it till I got no hesitation when I gunned it wot and still got max rpm. I now use them on any carb bigger than a 19mm. its made tuning carbs so much easier. 2 strokes need vacuum during throttle to pull the fuel from the carb bowl. if carb is too big, air just flows through the venturi without pulling fuel through the jets. ill take a pic when I can of my "half lid carb hat"
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Post by repherence2 on Aug 17, 2019 9:46:25 GMT -5
is the pod filter still dry? ive had issues when they get oily or gas soaked from carb spit back riding the night before. if theyre dry, then I agree with repherence2. I made an intake defuser out of half a spray can lid. then trimmed it till I got no hesitation when I gunned it wot and still got max rpm. I now use them on any carb bigger than a 19mm. its made tuning carbs so much easier. 2 strokes need vacuum during throttle to pull the fuel from the carb bowl. if carb is too big, air just flows through the venturi without pulling fuel through the jets. ill take a pic when I can of my "half lid carb hat" yup, I think the hassle of making the diffuser and installing it, is well worth it. |
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