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Post by venom040507 on May 8, 2023 14:48:00 GMT -5
so i took everyones advice and am doing this all one step at a time squeezing as much out of this little 02 zuma 50 as I can. finally getting back to messing with it, i have the air box ported and screen and the snorkle out, so far that has been the best ive found riding wise its not screaming good top speed max ive seen so far with stock carb on an 85 jet was 36.7mph. I just put a 90 main jet in and am working on tuning my question is, I just had it out for a top speed run with the 90 jet and my air screw 3/4 out from bottom once warmed up it seem like im getting quite a bit of exhaust smoke while riding and after shut down tail pipe is still smoking pretty good. do i dare turn the screw in to half a turn out or should i be going back to the 85 jet or go to an 88 or 87? 39.5 mph was top speed with the 90 jet BTW
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Post by rtnifty on May 11, 2023 20:33:52 GMT -5
If you're smoking, you're likely rich. Is it sputtering on you when you open throttle? By 3/4, you mean mor than 2 or 2.5 full turns out? If yea then you probably safe to go down to the 87.
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Post by venom040507 on May 17, 2023 15:41:19 GMT -5
If you're smoking, you're likely rich. Is it sputtering on you when you open throttle? By 3/4, you mean mor than 2 or 2.5 full turns out? If yea then you probably safe to go down to the 87. no I mean I am 3/4 of a full turn out from 0. Its not sputtering at all but it has a small bog when i first start to twist the throttle goes away when i hit about 1/4-1/2 throttle. i actually figured out the smokiness was coming from the probably 9 year old oil that was still in it i put fresh amsoil in after i cleaned the oil tank out and the smoking stopped but then i started to notice the low end bog on take off |
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Post by Zino on May 17, 2023 16:42:20 GMT -5
Is this stock cylinder stock pipe ?
The stock air box with no extra holes works well all the way up to 90 cc and with and expansion pipe .
You have probaly caused more trouble for tuning by adding holes .
Simplest tuning
The main jet is for wide open throttle you want it to be able run the richest jet that gives you the best top speed
The needle is for 1/4 to 3/4 throttle you want responsive on off throttle
The pilot jet 0-1/4 throttle and for just giving it enough gas to keep it idling without feathering the throttle.
I start with main jet and then work the needle and then finish with the pilot .
By doing it this it cleans up the transition spots around 1/4 throttle for pilot to needle and 3/4 needle to main jet .
The stock zuma carb jetting is 1 1/2 to 2 turns out for the air screw.
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Post by bigmatthew86 on May 17, 2023 19:38:50 GMT -5
Cover your holes & get a filter. If you can’t get another air box off eBay. You’re not gaining anything & just making it harder to tune. If you have a kit, you can remove the snorkel from the stock box & it’ll flow enough air.
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Post by rtnifty on May 17, 2023 21:20:45 GMT -5
Ooh wow, if that oil was really old then that'll cause all kinda of weirdness. Yeah I go along with what the others have suggested. Porting the airbox really isn't necessary. On my RT, I was running stock air box, snorkel removed with a malossi 70 and a Yasuni Z. My jetting was 94 and 27.5 needle raised. Top was around 54/55 tucked.
If you're on stock 50 cylinder and pipe, you shouldn't be quite that high. May wanna replace the airbox or at least seal up the holes. As a reference at stock I was sitting a 77 and 17.5 needle at mid. Top speed was around 44ish - stock airbox with snorkel in.
Yours will obviously be a little different. But yeah, try covering up the holes.
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Post by venom040507 on May 25, 2023 11:53:29 GMT -5
yes it is still stock cylinder stock pipe. the carb is stock aftermarket (factory design different brand.) came with i believe an 80 main jet but even before porting the airbox it didnt want to idle let alone go down the road no matter what i did. i started working up in jet size 85 main 44 pilot got it running and idling but would choke and sputter above 3/4 throttle unless the air screw was 2 1/2 - 3 turns out. moved the main jet to the 90 that is in it and was able to get full throttle but it was getting hot at factory sir screw setting. i started turning the screw in 1/4 turn at a time and doing test runs until i got to 3/4 turn out when it seemed happiest (good idle clean all the way to full throttle) but it was starving for air from idle to 1/2 throttle so i started opening up the air box one 3/4" hole at a time got up to 4 and it finally started to find low throttle with out choking on itself. i stopped porting and pulled the snorkle out of the box and now its good from 1/4 all the way to full throttle but i can not get rid of the bog from idle to 1/4 throttle...Bigger pilot jet? or move needle? |
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Post by Zino on May 25, 2023 13:44:49 GMT -5
The air screw is for cleaning up the first quarter throttle.
Your chasing 2 demons you are richening up the jetting and then leaning out the airbox by poking holes .
It would be better if you plugged the holes and jetted from there
The factory carb with factory jetting ,stock unmolested airbox ,stock cylinder works great .
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