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Post by repherence2 on Oct 20, 2022 20:20:11 GMT -5
"challenging to tune" is Relative.
for someone like me, whose only option is to run a big pwk with the CT intake manifold that i have, you just learn to deal with it.
when i first got my license, i was cruising up Tantalus and i ran into 2 skateboarders. they were hitchhiking and i was stoned and didn't care so i asked them where they were going. they said, "however far someone was willing to take them." i took them to the top so that i could watch them ride skateboards downhill. i asked them what they did about the Speed-Wobbles and they simply said, "you just handle it, don't fight it." --Daryl Freeman.
that is the approach that i take with the OKO pwk, you just handle it. there is difficulties in tuning them, but the answers and remedies can be found on the internet.
for me, the pwk is pretty much all that i know right now. it is one of those things that, "you just handle it" if you want to run it. i love it's WOT performance. low-end solution is the venturi divider. from there, it is all Duck Soup.
-- an old timer submarine mechanic told me, "you know how make Duck Soup? you take a pot, fill it with water, put it on the stove on high to boil the water, when the water is boiling, you put the duck in the water. and there you go, Duck Soup!" simply said, keep it simple, and it Is Simple.
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Post by repherence2 on Oct 20, 2022 18:05:24 GMT -5
Bigger carb doesn't make sense to me if variator is already at the end.
you would never really know unless you tested it for yourself.
here on Oahu, Hawai'i almost everyone runs 28mm OKO pwk carbs. most are Honda vertical type engines with these 28mm carbs and then you got people like me that run the 28mm OKO on a Jog90 motor. all i can tell you is this, there is a night and day difference between a Polini CP24 carburetor at wide open throttle versus a 28mm OKO at wide open throttle.
but maybe that is an Unfair comparison. i ran the Polini CP24 on the stock rear facing intake manifold, but the manifold was "ported" on the reed valve flange side. the OKO allows you to run a large CT forward facing intake manifold, massive difference in Flow.
there comes a slight tradeoff for me. for big top end wide open throttle speed, i pay the price on the low end. however, i compensate the low end on this "pwk" style carb by using a venturi divider, it makes tuning the low end much easier on these "pwk"" carbs.
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Post by repherence2 on Oct 20, 2022 17:32:40 GMT -5
because it was actually a "JOG" YMS V8, i will document this here as well. the insides of a YMS V8 for "JOG" drawn out at 1:1 scale. this is what the inside of a half-wave pipe looks like.
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Post by repherence2 on Oct 20, 2022 17:28:54 GMT -5
Inside a YMS V8. i probed the V8 pipe that had the corroded runner. this is a drawing of what i probed drawn out to 1:1 scale. what is the relevance of this? just so that those that want to know can have some understanding of what the inside of these half-wave pipes look like.
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Post by repherence2 on Oct 20, 2022 17:14:43 GMT -5
i think that you are chasing a dynamic ghost.
there is nothing wrong with your tuning approach at all. there is nothing wrong with your applied logic either.
i think it is Vibration + Float Design of that carb.
i think that if you were using a carb that had a pivot float, it would be a very different experience. i think that Vibration + Float Bouyancy + Guide Pins + Angle result is a dynamic float inaccuracy. or rather, there is so much input interference that the float cannot properly self correct the fuel level.
i think that your Lectron carburetor might be worth revisiting now that you have a full race engine setup. now that you have a high strung engine, that Lectron might be the key that wakes up that dragon.
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Post by repherence2 on Oct 20, 2022 16:33:56 GMT -5
...I guess I don't have to worry about seizing at those rpms...
seizing is more about Temperature rather than RPM.
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Post by repherence2 on Oct 20, 2022 16:28:08 GMT -5
just bought a 2014 yamaha zuma 50cc with only 527 miles on it the speedometer is off by 5mph slow how do you fix it
i "recalibrated" my speedometer on my chinese 2 stroke moped. i did it by removing the clear cover. lifting the indicator needle over the "0" pin and letting the indicator come to a rest, you get to see the offset from "0" (Zero), where the indicator needle will naturally sit. i marked that position with a sharpie by making a black dot on the indicator face. then i did to my best to gently pop the indicator hub off of the speedometer pin, to make sure it was free and capable of making adjustments.
as i cross over into an adjacent district from where i live, there is a radar speed limit sign that gives real-time speed. i use that sign to calibrate my speedo. in the beginning, from you starting sharpie dot/mark, you extrapolate 5 mph on the scale/arc and you advance the indicator by that amount/degrees and then press the indicator hub back onto the speedometer pin. make a few runs and see how it correlates between your speedo needle that the readout from the radar sign and make corrections accordingly.
...it can be done. **I "calibrated" mine to 45 MPH on the radar sign, beyond that i have no clue of tracking accuracy.**
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Post by repherence2 on Oct 20, 2022 9:12:27 GMT -5
People here in Boston are charging $90 for those boots.
Lawd Have Mercy! $90...? i never realized that you are in Boston too.
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Post by repherence2 on Oct 19, 2022 17:11:14 GMT -5
The Problem is that the Italkit 70ccm, that I have bought, does not run with 44mm stroke (+5mm) and 85mm connecting rod (+5mm).
In total this combo would lift the Italkit 10mm away from the motorblock. I think timings and everything else would be way off.
the way i see it, if you were willing to put in the work, that would be a KILLER full stroker engine. it would be just a tad over "Square Bore", which some have said is optimal. it would be 47mm bore x 49mm stroke.
"...timings and everything else would be way off," that is true, but if you have the skill and will, you could modify the ports.
i would imagine that you set the bore to a height where the transfer port duration is good. from there i would port the exhaust port upward to a suitable/target RPM range, and port the transfer ports downward. i think porting downward on transfer ports do less harm that porting upward on transfer ports because you do not change the roof angle. get one more of those "5mm Spacer Polini Evo," that you have on your list and you could have it machined/milled down to the height that is appropriate for the transfer port duration that you seek to make the Italkit perform how you like it (Blowdown). it may involve stacking some head gaskets too or making a custom head gasket.
my imagination could be totally wrong, but the way i see it, instead of being "boring" like the ported stage6 bores you describe, a square bore full stroker minarelli would be very intense with your c16.
if i were you, i would put in the work to mock it up. you will never know if it is workable until you put a degree wheel (or 360* protractor taped to cooling fan) on it to check the durations of the ports. but that's just me, i do not like "boring" too.
here in Hawaii, guys run "ministroker" cranks with Polini Corsa bores on the Honda based 2 stroke engines. ministrokers are simply cranks that have a longer stroke than the stock crank and most do not require machining of the case. they stack base gaskets to make it work and achieve the port timings.
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Post by repherence2 on Oct 19, 2022 16:35:23 GMT -5
It wouldn't be an air leak ? Like too much air coming in between the carb and the engine ?
sorry, i was under the assumption that you had already done a Leak Down Test. but yes, air leak would definitely be a problem.
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Post by repherence2 on Oct 19, 2022 16:31:56 GMT -5
i spy an outrigger canoe paddle hanging on your wall in the background (right) of this picture.
have you paddled in an outrigger canoe?
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Post by repherence2 on Oct 19, 2022 16:25:40 GMT -5
just give it lil' bit more fuel via main jet.
if you do not have a jet kit, buy one that goes in increments of 2 instead of 5. increase main jet until you reach the temperature that you are looking for.
what kind/brand of oil do you run?
is the 400* at wide open full throttle? or does it spike up after a full throttle run and you are off-throttle?
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Post by repherence2 on Oct 19, 2022 16:10:56 GMT -5
titiz67 welcome to the forum brother! i am excited to see what you will build. --Aloha from Hawai'i my bruddah!
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Post by repherence2 on Oct 19, 2022 16:07:13 GMT -5
from what i see in your pictures, from the way your engine mount looks, it appears to me that you could mount a Minarelli, Chinarelli, or a Polaris ATV engine on that bike.
as far as your question about wire harnesses, make sure you check what type of CDI plug you have on your existing harness. i am a 2 stroke guy so i basically only know "JOG" (yamaha) or "DIO" (honda). they have different CDI pin outs. one is a "5 pin" and the other is a "6 pin".
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Post by repherence2 on Oct 19, 2022 14:52:01 GMT -5
I think I like the dual chains. Does this result in a more reliable or less expensive way to have pedal power and/or engine power? How do they operate separately? thanks!
jackrides there is a detent button on the clutch lever that is mounted to the handle bars. if you want to ride like a regular bicycle, you squeeze the clutch lever in and press down on the detent button to keep the clutch lever in the "disengaged" position.
you pedal the bike the like a normal bicycle. however, it is heavy as hell with the engine kit and you fight some of the drag from the engine drive chain, even though the clutch is disengaged.
you ride it like a normal bike, you get up to speed and then you "kick start" the engine by quickly squeeze/tapping the clutch lever. by doing that action, the detent on the lever releases and the clutch engages and "kick starts" the engine. when you want to come off engine power, you pull the clutch lever in and press in the detent button to keep the clutch in the disengaged position, and then you hit the Kill Switch on the throttle assembly.
it's a pretty neat contraption. it works. and it's pretty trippy doing 45 MPH on a 26" wheel beach cruiser that only has Coaster Brakes (push back on the pedal to brake). it gets pretty exciting LOL.
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