I put a pipe and a K and N filter on my fiddy. What size jet do I need and where do I get them?

 

what size carb ?
stock or a big bore ?

 

If its stock try a 60 or 62. Im using a 60 with my uni pod filter. You will probably have to move the clip up or down a notch after putting the jet in.

 

Its a stock carb

 

60 is stock..all the make is 62 and 65

try moving the needle up one

 

58 is stock

 

Try to find a location with a smooth hill that is long enough to run in 2nd or 3rd gear at 3/4 to full throttle.

Ride up the hill in 2nd or 3rd with the throttle at 3/4 to full position. The engine should hesitate and stutter slightly if the jetting is rich.

Drop down one mainjet size and test again. The engine should perform better. If there is still a stumble or hesitation, then drop down one more jet size.

If jetting down does not change the power delivery, or makes it worse, then the jetting is lean. Install a jet that is 4-5 sizes larger than stock and test. If the power delivery still does not change, or gets worse, then there is another problem not related to jetting.

Once the engine performs crisply at 3/4 to full throttle, ride the same hill from 1/4 to 1/2 throttle to check the needle jetting. If the bike feels sluggish at this point, try moving the needle clip back to the middle position.

Some engines will also require a change in the idle screw setting or pilot jet change. NOTE: When adjusting the idle screw, take note of its location: If the screw is in the back of the carburetor, screwing it out will lean the mixture while screwing it in will richen it. If the adjustment screw is in the front of the carburetor, it will be the opposite. If turning the screw between one and two and a half doesn't have any affect, the pilot jet will have to be replaced with either a larger or smaller one. While adjusting the pilot screw, turn it 1/4 turn at a time and test run the bike between adjustments. Adjust the pilot circuit until the motorcycle runs cleanly off of idle with no hesitations or bogs.
rest of the info is here:
http://www.powroll.com/tech_specs_jetting.htm

 

k dudes not even kidding. I can not get the hesitation out of my bike right off idle tried 60 main both with stock needle height and one higher. Then i went back to stock 58 jet raised needles two clips. got most of it out but still notice it every once in a while. donsnt seem like i have any power down low. Do I just need to gear down or what cause i cant wheelie this thing for ****.

Help!

 

Im no expert at carb tuning but this method worked pretty good for me. Once your happy with your jet and clip setting. Put the bike in 2nd on a flat road. Then Gun it. If it bogs or hesitates, turn the mixture screw. Repeat. If it gets worse, turn it the other way. Keep doing this until the bike takes off in 2nd.

 

yep...you gotta adjust the mixture screw.

 

Put the 60 jet back in, put the clip in one slot below the middle one. Thats where I had my bike witht he UNI filter when it was stock. Then it took 5/10 minutes of messing with the air screw. Leave the idle screw alone if it idles fine.

 

only thing is, with a stock 50 carb, the pilot jet is made into the carb, on the brass tube next to the main jet, correct? i took the bowl off mine like 2 weeks ago, i took the snorkel/cap off the airbox, and it didnt like it at ALL, i was gonna put a bigger pilot in it because the mix screw just wasnt doing enough for it, and my shop doesnt even have the fk's up looking jets that came outta my carb. so, i wound up puttin the airbox back together, putting the needle clip on the 4th notch from the top, back to stock, she likes it that way.... till i go dickin around with a big bore kit and exhaust. i found a place that sells XR70 carbs for $60 new, but it looks identical to the 50 stock carb, only a little bigger. im wondering if it has same type of silly *** jets in it too. thats one thing thats keeping me from sinkin any $ into the engine... if i go putting exhaust or a filter on it, im gonna wanna make it run good, and run right... cant tweak it if i cant change the main jets and pilots.

 

excelent point diingo
and thesre guys dont get that when you phuc with it
**** messes up
only thing i can recommend is a filter with a velocity stack
made into it k&n makes them
otherwise youll never get the hesitation out
because the carb doesnt have the air velocity
comming into the carb as it does with the stk airbox on it
in other words it isnt nearly as effiecient at mixing the air/fuel
ive read were guys say the lil stack on the air box is the first thing they cut off if not tossing the whole airbox,thats a mistake
jetting is twice as difficult if you havent a clue about certain things
like how a carb works air velocity pressure waves ect.
the secret to bottom end on a 50 is buy a 12/40 sproket set up
and put it back stock itll get wheelies in all gears
jus wont go very fast ,but if your stunting you dont care about fast

 

i found a good combo..... i put a FMF powercore 4 on mine, and took the airbox lid off..... it actually feels like it has some *** behind it now, especially after the +3 rear sprocket, and -1 front sprocket.



how do you know when a hobby turns into a sickness?

 

When you spend too much $$$ on the little guy. Since I bought mine, stock, i've spent WAY to much $$$ but it's gonna be pimp. :YEAH

 

it has some *** in it cause you geared it taller
not from the pipe or the airbox mods