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Post by newbscootdude on Jul 31, 2013 19:54:27 GMT -5
ok so the first thing i did was max my f/a, actually had to lean it out a little from factory. now my question here is bc i had to lean it to get proper f/a does that mean that my jets are already to big or is it the other way around? anyways i took it for a short little ride and my scoot was poping and backfiring pretty bad and my plug looked like it was running really lean so i started opening the f/a as soon as i did the idle rpm dropped so i uped the idle screw allowing it to idle but not stall on me. i did this a couple times until i no longer heard the poping and backfires when i let off throttle. well now once i hit 35 the bike sputters and looses a lot of power just like its running rich and when i checked the plug again its running way to rich and i only opened the f/a up by about 2 full turns before it stopped poping and backfiring. so my question is do i need to upjet or down jet to achieve proper tuning here? and then i had a question about the main jets im looking to get. ive noticed that most of the main jets on ebay say either 5mm, cvk, or kenhin, or a mixture of 4-6mm with any one of those names. scrappy says my carb is a runtong, but it has K N the standard of japan stamped into the side of it which ive heard to be kenhin carbs. so how do i know which mm size jet to get and what brand? Would it be easiest to take my carb apart and just measure what ive got in there? this still leaves me with the question about the brands tho? does it really matter what brand i get or is it just certain brands are "better" than others just like everything else? Oh and when i mention the mm size of the jet i dont mean like 105, 110, 115 which is the jet size, i mean the width of the threaded part of the jet such as the measurement all the way to the left on this pic m259.photobucket.com/albumview/albums/turbostang331/MikuniVM1122.jpg.html?o=268 |
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Post by jerseyboy on Jul 31, 2013 20:18:33 GMT -5
This was the kit I got for my 150 with Kehin 24mm,I had to use a 118/42 with UNI and free flow,,it had a 102 from stock,,wouldn't even run after half throttle...lol The way I set my A/F is,,warm up scoot,,then turn it CW until it starts to die,,then back it out CCW till the rpm gets to its highest point,,after that I just crack it back CW a hair,,takes the fuel like a monster and plug looks nice... www.ebay.com/itm/271121178696?ssPageName=STRK: |
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Post by newbscootdude on Jul 31, 2013 20:21:56 GMT -5
ya thats what i did at first and was getting all this poping and backfiring which is the main reason im confused.
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Post by jerseyboy on Jul 31, 2013 20:26:43 GMT -5
[replyingto=newbscootdude]newbscootdude[/replyingto]Sounds like your gonna have to play with it for a while,,its being a little stubborn. If it where mine,, I would set it like you did when it popped,,and just upjet a few sizes,,that should straighten you right out.  |
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Post by newbscootdude on Jul 31, 2013 20:30:14 GMT -5
any other suggestions?  |
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Post by newbscootdude on Aug 1, 2013 12:56:21 GMT -5
no one?  |
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Post by jerseyboy on Aug 1, 2013 13:42:25 GMT -5
There really isnt much more you can do bro but play with it,,you could mess around with your air box also for tuning,,drill some small holes in it,,then cover them up with duck tape if it makes it worse,holes will lean it out more!...
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Post by newbscootdude on Aug 1, 2013 16:55:47 GMT -5
be careful this video is loud.
ok well since there isnt much more i can do excpet play around with it given the information i provided and you can see my setup in my signature plus the video you just listened to should i up or down jet? or should i just buy a range of lower and higher jets and figure it out?
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Post by jerseyboy on Aug 1, 2013 17:10:22 GMT -5
[replyingto=newbscootdude]newbscootdude[/replyingto]Almost sounds like an electrical stutter to me cause its intermittent,,could be a loose wire on coil or something in that area,,the decel popping was not too bad,,and it takes fuel good from out of the hole,,40 mph is pretty good for what you have going but guys are getting a bit more,,almost sounds like its starving for fuel at high rpm,,maybe your loosing vacuum and the bowl is running low,,man its hard to tell bro,,sorry I couldn't be of more help,,BTW the A/F only effects the bottom to lower mid and your good there...also reading your sig,,make sure all your intake gaskets and ports match,,you can get bad turbulence in the intake mixture that causes motor to run funny from mismatched ports and gaskets. Also is a 24mm carb what guys are running on those,,sounds like alot of fuel to me,,especially with a 105 jet,,most guys where in the upper 80 lower  's for main,,my 150 has a 24mm carb and its PLENTY of fuel,,i even know guys who run the 180 BBK that use a 24mm with a 120 and its plenty of fuel... |
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Post by newbscootdude on Aug 1, 2013 17:45:51 GMT -5
you know i did have to manually cut my intake gasket to size. the edges where a little rugged but i tried my best to smooth them out without comprimising the gasket. it has a fuel pump on it my gas tank is below my feet. i do have my starter wiring unplugged and wrapped up to my frame. i have the electrical connection wrapped in the rubber boot tho. i am completely unfamaliar with the coil so ill go over it and check for any loose connections.
thanks for the tips
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Post by jerseyboy on Aug 1, 2013 19:57:25 GMT -5
yes sir,,we will figure it out,,just have to rule stuff out one at a time..the coil is at the end of the spark plug wire(on opposite end)looks like a little canister with two wires going to it,,sometimes the clips get loose and cause intermittent sputter like yours,,you can cut,strip, and hard-wire solder them direct,,or just squeeze the clips a little tighter with a pliers so they bite the post on the coil better.I would check all your cdi connections(plugs)spark plug boot,and also the ground wires,,just to rule out electrical.Ive even seen a kill switch that was going bad or dirty cause sputter,,might want to wiggle it a little while you are WOT and see if it sputters by touching switch...
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Post by newbscootdude on Aug 1, 2013 19:59:31 GMT -5
will get right on that and report back.
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Post by sickopsycho on Aug 1, 2013 20:24:39 GMT -5
I posted on one of the other thread but I'll write it again- 105 sounds way too big for a 72cc motor. I have a very similar setup to yours and am running with an  #. Same bbk, same intake but stock carb. an  # was too much gas for my bike... ymmv. |
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Post by jerseyboy on Aug 1, 2013 20:27:25 GMT -5
[replyingto=sickopsycho]sickopsycho[/replyingto]Yeah not sure if I ever saw somebody use more than a  in this set up.His slow jet looks a bit big also,,my 150 ran great with a 38 and all my mods.I just put a 42 in there cause it was hard starting cold,,plus I have a 60mm BBK on the way...hehehe |
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Post by newbscootdude on Aug 1, 2013 20:45:26 GMT -5
ok so just went over all the wiring and one of the coil wires was loose but its still doing at 35 religiously everytime i hit 35 it stutters. does this mean the engine is getting too much gas? and i will be buying about 2-3 spark plugs tomorrow so we can really see whats going on in there
so should i just go back to stock carb and put bigger jets in it?
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(need 112)
's for main,,my 150 has a 24mm carb and its PLENTY of fuel,,i even know guys who run the 180 BBK that use a 24mm with a 120 and its plenty of fuel...
#. Same bbk, same intake but stock carb. an 
# was too much gas for my bike... ymmv.
in this set up.His slow jet looks a bit big also,,my 150 ran great with a 38 and all my mods.I just put a 42 in there cause it was hard starting cold,,plus I have a 60mm BBK on the way...hehehe