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jetting all jacked up


Overboost

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ok, first off, I did a search, and have not yet found what I need.

 

here is my dilemma.

 

first off, jetting WAS main=155

needle dropped 1 clip

pilot=45

carbs, pwk33

mods are in sig

 

it ran OK....slight bog off line, while revving, taking your time, it runs fine, only when you try to launch hard, second gear launch, give it up, will bog to the point it will stall....

 

pulled good in the mid and top was good, topped 76mph in dirt, stock gearing

 

when you ride around in trails, part throttle, it seems to chug, surge and have no power in the mid, have to downshift to get any power out then it rips just fine

 

what I did=

put needle mid clip, upped jets to 160 main, no change on pilot

 

what it did=

bogs bad off the line and lost alot of top end pull

mid throttle surge almost gone

 

if you let off clutch easy and ride around the parking lot, no issues, no surging, no bog nothing, but once you really get going does it fuck up

 

I have no happy medium on the mid and off idle, when I fix one, the other gets worse.

 

my air screws are also out 3-1/2 turns, so I know I need to drop the pilot but a 42 or a 40 with my mods? I think somethings not right, and the better I get the top and mid to run, it gets so bad on the bottom end its almost unridable?

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You should be either at 45 or 48 pilot and 160 or 162 main. Put the needle in the middle and air screw two turns out. The PWK carbs all run about the same jetting on most motors. If you aren't pretty close to these jetting specs, something else is wrong.

 

Will the bike sit and idle? If so, does it load up? First thing I would do is get the bike idling good with 45 or 48 pilot.

 

Next, get your main jet set correctly. Install a 160 main and do a WOT plug check. Inspect plugs. Dark = rich, white = lean and tan = just right. Adjust accordingly.

 

Put the needle in the middle and leave it for now.

 

Once you have the above done, let the bike idle and stab the throttle. Adjust the air screw until the bike will rev up cleanly when stabbing the throttle. You will probably end up at 2-2.5 turns out.

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You should be either at 45 or 48 pilot and 160 or 162 main. Put the needle in the middle and air screw two turns out.

 

 

thats where I started and am right now, 45 pilot, 160 main and 2-1/2 turns out, and it wont run worth a squat. thats why I am so puzzled.

when I tune one circuit to run good, it dicks something else up on another circuit. I started at the bottom and made my way up, and the more I tune the worse it gets someplace else.

 

edit: I also had the motor done at fast so I dont belive there to be any air leaks, they test all that fun stuff, I just got it, put on carbs and installed it.

 

I dont believe it to be the build, its in the jetting someplace...just need to track it down. it always winds up being something stupid

Edited by Overboost
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thats where I started and am right now, 45 pilot, 160 main and 2-1/2 turns out, and it wont run worth a squat. thats why I am so puzzled.

when I tune one circuit to run good, it dicks something else up on another circuit. I started at the bottom and made my way up, and the more I tune the worse it gets someplace else.

 

Then I think you have other issues. Have you checked for an air leak? Are you sure your electrical system is up to par?

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Then I think you have other issues. Have you checked for an air leak? Are you sure your electrical system is up to par?

 

 

ran perfect before I did the 4mil

 

I only did a 4 mil cuz my piston broke in original motor and if I am going to rebuild it, I went with something better.

I been fighting with jetting since day one

 

anyone in the flint MI area that would like to try it out, see what they think? 4 heads are better than one.

dont need much room to ride, just a good area to launch and enough room to hit gear 2

Edited by Overboost
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just a general plug read (driving around, all conditions, pull plugs and check)

 

they are black and wet, so I am way too rich someplace

 

You need to do a WOT (wide open throttle) plug check. Just riding it around shifting up and down through the gears is not the correct way to determine whether or not your main jet is correct.

 

Everything else aside, your jetting should be very close to what I listed above. If not, something else isn't right. Maybe you have a faulty electrical system and it's not getting good spark causing there to be leftover fuel and oil in the cylinders.

 

Are you sure you have good spark?

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That's what I was thinking. I got 1800' of dirt road in front plus drives on the farm if you want to bring it to Ortonville. Bring all your jets and some new plugs. Probably couldn't help with a stator cause Larry's is round plug , but can use coil. PM if interested

:cheers:

 

on third coil, second flywheel. spark is good. nothing changed

 

I dropped needle to last clip, whole new animal. runs really good, just need to get it in a trail but it has no chugs just riding around like it did, slow into throttle now rips the ground out from under it when it used to just bog and have to catch up.

 

one out where I can run it WFO I will check mains but my main concern was it would not run idle to 1/2 throttle, WFO was always good

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Presume different plug caps with different coil? Have you tried a different cdi ? Do you have any other carbs to try? Are the slides sloppy in the carbs? Were the carbs off a snomo by chance?

 

totally diff coil, diff caps and wires

have not tried a CDI, these carbs I bought brand new, so I dont have another set laying around, slides not sloppy, hence they are brand new, about 50 hours on them. not sled carbs, say motorcycle racing use only on box.

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Just trying to hit all the bases. Do you plan on getting a leaner needle? :cheers:

 

 

it has CEL needles in it now. I will take you up on the farm road offer, I have no place here in flushing to try it. and trips to st helen just to figure out its not right is getting to be a pain in the dick...

 

I am only trying it in my back yard, from front to rear is 250' so its not a "good" test

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