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Pages: (2) [1] 2  ( Go to first unread post )

 Carburetor Jetting, Need t know how can I determine JET SIze
daraji89
  Posted: Mar 24 2007, 03:57 PM


LT Corporal


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Posts: 117
Member No.: 212
Joined: 7-February 07



GOOD MORNING PEOPLE...

I opened my carburetuor (the Keihin PWK 72RA4 39mm) and the main jet size is 182 as far as now I know that this jet is too rich, because of the black plugs the LT500R is burning, and they dont last more than 2-3 days.

What I need to know is how can I determine the proper jet size for my lt500R, since their is jets from Size 80 - 230, my lt500r has the following mods:
1. pro design cool head
2. 1990 model
3. Keihin 39mm racing carb
4. headers maybe fmf ones do know the brand

thats all !!!

I appreciate your help and time people, thanks alot.
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quadzillaripper
Posted: Mar 25 2007, 07:18 PM


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I just do plug shoots & aim for the coco color.
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DR Q
Posted: Mar 25 2007, 10:52 PM


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Hi,
You need to first understand that the different circuits in a carburetor affect the air to fuel ratio at different throttle postions and RPMs.
A main jet is just for wide open throttle metering.
MANY factors affect jetting including altitude, air density, and fuel make-up.
If it starts and idles OK, ! would lower the needle (raise the clip) 1 notch and read the plug after riding around at 1/4-3/4 throttle.
A 182 main is in the ballpark.
$.02
RK
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daraji89
Posted: Mar 26 2007, 07:00 AM


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Ok I see now DR.Q, I will do what you say and tell you the results.

thanks alot for your time and advices.
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daraji89
Posted: Jun 10 2007, 04:12 PM


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buy the way i also had a problem in the jetting the main jet size was 182 and the plug use to be burned within two days or three, now i installed a 170 main jet and the plug the B8EGV looks brown and around the iron screw like there is black powder is that normal or not?
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daraji89
Posted: Jun 13 2007, 09:42 AM


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hey Dr.Q how are you doing? hope good I installed 170 main jet and the plug from the insdie color turned to brown after one ride about 40 minutes but around the plug where the screw like steel design there is black powder is that good or not, and by the way the crank is stuck its not moving anymore? any solutions?. thanks for your time.
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Joe Rock
Posted: Jun 13 2007, 02:02 PM


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The crank is stuck? OUCH

Are you sure its the crank...if you were playing with jetting...maybe you toasted piston? Have you had top end off yet?


--------------------
Joe

08' YFZ/500R (In Process)
90' LT500R
92' 250/500 Hybrid (In Mockup)
88' LT250R
05' F-350 CC Toy Hauler
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daraji89
Posted: Jun 13 2007, 08:33 PM


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the mechanic showed me the piston and head everything was ok but the crank is stuck, and i have changed the jetting from 182 main jet to 170 even when it was at 182 it stucked with me twice in the desert, anyway when I took it the first time it got stuck to the shop he just moved the gears beside the clutches then it was ok and then it got stuck again and when i reached him with lt500r on the trailer the crank moved and it was ok and now it also stuck the third time and I dont know what to do and am new reider on the lt500r i dont know much about it so what would you say where is dr.Q i need his help before i buy anything....
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Skully
Posted: Jun 14 2007, 02:27 AM


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Sooooooooooooo..........
What you are saying is the kickstarter is stuck, not the crankshaft...... Right?

Jim


--------------------
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1987lt250
Posted: Jun 14 2007, 03:21 AM


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yeah i left a penny in my clutch side after changing basket had that happen, whats sense of being stupid if i dont carry it out now and again?


--------------------
1987 LT500 basically stock.
1987 lt250<<<<<<<<<FOR SALE
paul turner national kit
pyramid rad valve
pt pipe
38mm airstryker
99 warrior to tow me home (the womans)

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daraji89
Posted: Jun 14 2007, 07:42 AM


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yeah skully the kick starter is stuck because the crank is stuck and doesnt move anymore but what i dont know yet is if there is something stuck inside the gears the clutches side of the case. so what is it to say skully? : )
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Joe Rock
Posted: Jun 14 2007, 12:27 PM


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Dude, I am confused! Does this happen when starting it? Or riding it?

Kickstarter = Crank? Meaning to crank it over? Not the actual crankshaft?

If kickstarter is getting stuck, you might want to pull the clutch cover of and take a look. Get a better idea of what is going on in there...no biggie...just a few 8mm bolts and a gasket. But I would want to know what is going on, see for myself.


--------------------
Joe

08' YFZ/500R (In Process)
90' LT500R
92' 250/500 Hybrid (In Mockup)
88' LT250R
05' F-350 CC Toy Hauler
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bellracing2
Posted: Jun 14 2007, 03:19 PM


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It almost sounds like he's talking about the engine crankshaft . Maybe a bad bearing heating up and siezing and when it cools it lets loose , but he should be able to take off the flywheel cover and check for play . Maybe he needs the case mod for the bearings that are spinning in the cases ? sad.gif
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daraji89
  Posted: Jun 14 2007, 09:03 PM


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the engine crank is not moving which makes the kick starter stuck it happened 3 times with me, the flywheel does not play anymore also because of the crank. it happened with me when i am riding it for 40 minutes or so 3 times, and tomo am calling my mechanic to check again and make sure that there is nothing except what i have mentioned.
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bellracing2
Posted: Jun 15 2007, 01:15 AM


somewhere between a sasquatch and Chewbaca


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If the crank is seizing you need to STOP RIDING IT !!!!! you are only doing more damage ! The motor needs to be taken appart .
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