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PZ19 Carb Tuning

90K views 41 replies 10 participants last post by  410cjak 
#1 ·
How do I tune this carburetor to the area that I am currently in which is Toronto, Canada?

The bike used to run fine but I could tell it could use some tuning. Now when I am riding it, It will shut off alot like every 100 meters or so and will be a pain to start back up. I need it tuned back so this doesnt happen and that it runs at top speed

Also, what settings does the throttle cable needle be at if the tip of the needle is the "top"?


 
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#2 ·
How do I tune this carburetor to the area that I am currently in which is Toronto, Canada?

The bike used to run fine but I could tell it could use some tuning. Now when I am riding it, It will shut off alot like every 100 meters or so and will be a pain to start back up. I need it tuned back so this doesnt happen and that it runs at top speed

Also, what settings does the throttle cable needle be at if the tip of the needle is the "top"?




Theres a restrictor tab in that carb in the bottom of the bowl that needs to be removed with a dremel...The tab holds the float too high so the fuel just dribbles past the needle causing a fuel starvation problem when coming off the throttle after a highspeed run.......



after you remove the restrictor tab set the c-clip on the needle to the 4th notch,,float at 10 degrees and the a/f mix screw to 2 1/2 turns out.....
 
#4 ·
I cleaned everything so far, i dont have a dremel or anything to grind away the tab but I know what you are talking about.

-The needle being 4TH from the top, is the top the needle tip or the other side?

-The air/fuel mixture screw, is that the screw on the angle or the one that sticks straight out?

-How do I set the idle screw?
 
#5 · (Edited)
I cleaned everything so far, i dont have a dremel or anything to grind away the tab but I know what you are talking about.

-The needle being 4TH from the top, is the top the needle tip or the other side?

-The air/fuel mixture screw, is that the screw on the angle or the one that sticks straight out?

-How do I set the idle screw?
From the blunt end of the needle is considered the top,,,The sharp end is the tip and the bottom...the slots go from 1-5,,bluntend to sharp tip,,,1 is leanest setting and 5 richest setting........seeings its getting cooler out you want the 4th notch....[second from richest setting]

The a/f screw is to the left of the idle screw and is slotted...the phillips screw with the spring to the right is the idle screw

the idle screw should be set to 1500 rpms and can be set by ear.........

the a/f factory setting is 2 full turns out,,seeings its getting cooler out youll most likely tune-in at 2 1/2..............
 
#8 · (Edited)
I also have another potential issue, before I used to cold start the bike with the level for choke in the OFF position and when I wanted to ride, I twisted it up to ON. Now the bike bogs out when I try riding with the chock ON and rides barely without shutting off in the OFF position.

And when I tune the carb, should I have the choke in the ON or OFF position (based on what I said above)?
 
#13 ·
My new 125cc ATV, the pilot jet clogged right away, I changed from a 20mm China carb w/ no air idle screw to a Japan carb, drilled the pilot jet and main jet one size bigger, two weeks later had to pull the bowl and the pilot jet was dirty already. In California the run 10 percent alcohol in the gas in the summer, and that don't help the cheap China rubber,lol.
 
#14 ·
They lie and say 10% ethanol...Its up to 22 percent blend now around here....Their goal is to fudge up carbs and the older fuel injection systems to get rid of them vehicles...good thing my 91 F250 has an MSD ignition that will burn anything cleanly and an ethanol resistant fuel regulator.........
 
#17 · (Edited)
Because the bike was jetted in China and not jetted for the current temps or altitude..When I lost my airbox and added a hp foam airfilter NGK sparkplug I had to up the jet from the stock 73 to 75....After the hp sparkwire,,race CDI and head breather mod I had to up the mainjet to 78...Youll be surprised how much restriction the stock snorkle box has...........

Even brand new Japan dirtbikes and such dont run right straight out of the crate...thats why you pay a preperation fee........They put it together,,change out the shipping oil and get it jetted right and running smoothly................
 
#20 ·
i dont have the bike tuned yet so would that affect the jets?
Getting your jetting correct is part of the tuning process. Even if the bike was still bone stock, with the stock filter setup, If the air density changes enough, you need to change the jetting to remain at optimal performance. Jetting is not a 'set it and forget it' thing.

And, as was said before, You tune with the choke OFF.
 
#21 ·
Cam2 remember when they changed the diesel fuel, I was still in college getting a diesel certificate. I had my 10 wheel Kenworth w/ a Cummins turbo charged big bore. The new fuel was eating up the rubber seal in the fuel injection pumps, and the trucks were ready to kill the guy that made the fuel laws. Now, they are trying to make them pay $27,000 to add Smog stuff to there trucks,insane!!!
On the carbs, thats why like Cam2 I love Walbro carbs easy to rebuild and easy to keep in tune.
 
#24 ·
Cam2 remember when they changed the diesel fuel, I was still in college getting a diesel certificate. I had my 10 wheel Kenworth w/ a Cummins turbo charged big bore. The new fuel was eating up the rubber seal in the fuel injection pumps, and the trucks were ready to kill the guy that made the fuel laws. Now, they are trying to make them pay $27,000 to add Smog stuff to there trucks,insane!!!
On the carbs, thats why like Cam2 I love Walbro carbs easy to rebuild and easy to keep in tune.
Oh I remember it well...It wreaked havok on my 6.9 turbo diesel flatbed I had then...Some very tedious and expensive fixes for me at that time.....I think the DIP costed me around $1600 and the total job almost $3gs with me doing it myself........
 
#22 ·
your supposed to tune a carb after it has warmed up to normal operating temp
the first thing to do is test the main jet, pilot jet, then the needle clip, then air fuel and idle
it also requires you to know what the bike is doing in certain ranges, idle, off idle to 1/4 throttle, 1/4 to 3/4 throttle and wide open throttle
the ethanol is killing carb jets, i used to be able to let my bike sit months without cleaning the carb, now its getting clogged in a few weeks
maybe if the gas was made of rice it would run correctly lol
 
#26 ·
I have a question regarding thosequotes if I just purchased a PC 19 rebuild kit if I rebuilt carburetor with all the supplies if hearts if I have the needle set on the leanest setting in the air fuel screw all the way in on my Carb and my bike is still running really rich is there anything else I can do??
 
#28 ·
I changed the main jet to the main jet that came in the kit only thing that only thing that I didn't do was Dremel of the tab at the bottom of the fuel bowl so the float will be able how to go down a little farther and I'm getting good blow throug with my air tool for all of the hol with my air tool for all of the holes and openings in the carburetor I don't know what else to do I don't know what else to do other than to buy a brand new carburetor
 
#31 ·
There is no works for everything set up. You have a choke jet, pilot jet, and main jet, and the 5 slot clip on the piston needle to make adjustments. Most of the time I have trouble with the bike cutting out and stalling and not running, the pilot jet is clog full of the crap additives they put in your gas and when you let it sit along time the gas turns to gum and clogs the pilot jet. It's very small, .018" to .020"
As the air gets colder you need a bigger main jet.
 
#33 · (Edited)
Its most likely too lean..If it was too rich the engine would surge and literally Chirp aswell as foul the plug......The best way to actually tell is to literally pull the plug to see if its black brown or white......

Have you tried adjusting the a/f mixture screw to tune it in...?Thats what theyre made for......

Try turning the a/f mix screw outwards 1/2 turn richer and see if that makes it run better.,,,If not turn it 1/2 back in plus 1/4 more......

If it does start to run better and it takes 1 full turn outwards[richer] to get it running good get a bigger pilot jet 1 size bigger..Good Luck
 
#35 ·
Okay so I have some similar issues to a point. I have a Baja 90cc quad and i just completely rebuilt the carb. I have been looking online for a tuning diagram, but I cannot seem to find one. To the point now, I can get the quad started but it has an extremely high idle and if you don't hold the break it will actually start to take off on you. Then when riding it and having it at about half throttle it tends to just bog down and has a bad smell to it. Any ideas?
 
#38 · (Edited)
A 19 isnt too big for a 50cc as long as the carb is jetted right.....50's/70's90's and 110cc engines are built with E22 heads....My modded CRF70 had a 20mm carb.....It was jetted 40/85


Fuel/air adjustment screw is 2 full turns out

C-clip setting is middle notch[3rd]

Float setting is -10 degrees

pilot jet is # 38 factory

main jet is #73 factory
 
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