carb and jetting 83 cr 480? need some help please!

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#1
i'd like to get everyone's thoughts on the keihin pwk 38mm carb? i've been thinking of upgrading to this carb for my 480, either the air striker or regular. i'm not really sure the difference. and also what would be an ok starting point for jetting? A little back ground i' ve been trying to get this bikle jetted correctly for a few weeks no with no luck. i'm running the stock PE carb with a 178 main and a 65 slow jet. the needle is in the 2nd from the top. air screw out 3 1/4 turns. which means i need a smaller slow jet. i've also checked the float level and set to 7/8 to 13/16. temps around 40-60 degress and 500 ft elevation.the bike runs pretty good on top. but seems to be sluggish and bog when you blip the throttle. i haven't been able to chop the throttle cause i can't get the 1/8 to 1/2 throttle set right. also the bike will not idle unless the throttle slide is adjusted up. So for these reasons i have been thinking about a new pwk carb and starting fresh. mods include k&n filter(new) DG head pipe, DG silencer, fmf torque reeds, and bored to the max (91 mm) air box has also been modded with 1 inch plugs(6) to allow more air flow. any help with a good jetting starting point would be very helpful. and if I were to get the new 38mm carb what should i get for jets to start with.

thanks
Shawn
forgot to mention the PO did some intake porting(home brew style). not sure if that matters much, but probably! sorry for the long post.
 
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#2
Well i am of no help because i am a Mikuni guy. My 465 uses a 340 main with clip at the top of needle and #45 pilot. Try using a search engine to help out. Try out a 185 main, 68 piolit, with 3rd clip position.
 
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#3
hey shawn ..just restored a 83 480. my main jet is 180 and the needle is also 2nd from the top but my air screw is only out 2 turns and idles good the slow jet im not sure of but i bet its original what ever that is...mike
 
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#4
thanks for the replies guys. but i was under the impression that if your air screws was that far out its to rich and needs a smaller pilot. correct? my plug is usually wet and oily. meaning rich again, i think. i'm not a jetting pro. anyone else have any thoughts?

Mike thats cool I restored mine about 3 years ago, but never rode it after. My friends are not much for outdoor stuff. but i got into it this summer. solved a hard start issue, by replacing the clutch side crank seal. and been trying to jet the carb correctly ever since. it runs pretty good up top, but down low not so good. but its a fun bike. I can only imagine what its like properly jetted!
 
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#6
whenfoxforks-ruled said:
Material was removed from that cylinder, it may NEVER run correctly.
i'm ok with the idle being eratic, but shouldn't i still be able to get it jetted atleast close? like i mentioned its only down low. i understand what your saying, but shouldn't I be able to get it closer than 3-4 turns out? and if not i'v got a spare cylinder. just needs a freah bore! :nod:

and thank you for your time!

Shawn
 
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#7
my bike i can slow right down in 1st and crack it.it just takes off and pulls as hard in 5th as it does in 1st,pretty scary wher you hit a pach of hard packed dirt it just goes straght up usually when yor not ready.im putting some pics up soon just wating for my new tank decals they are coming this week anyway mine idles great warmig up and the plug is a darker brown maybe not perfect but close.mike
 
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#8
All them passages are engineered to be that way and removing material must be put back in somewhere. Otherwise the motor will never breathe properly. Can not get it jetted is a good symptom. Rule number one in jetting, rule out all mechanical factors. Early cr 125's were fun to "port", and to some degree seemingly ran good, BUT it was not the ticket at all! There is a science to the motor, there are software programs for these people with tools to learn how to properly put a porting tool in a cylinder. http://www.optimum-power.com/products-e-design.htm, Enjoy it as it is or throw it in the scrap heap, fix the other jug.
 
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#10
ordered some new pilots yesterday. I'm gonna try those and see what happens. I'll let you know how it goes this weekend!

About my other question. anyone have any thoughts on the pwk 38mm air striker or the "base" model?

Again thank you all for your replies!

Shawn
 
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#12
Update: I tried a few different pilot jets yesterday and today. the bike was getting stronger and stronger the lower i got on the pilot. #60 felt a little better with the A/F screw out 3-3.5 turns. #58 better than the 60, A/F screw 2.5- 3 turns out. i noticed a pattern here with the A/F screw so i decided to skip the #55 pilot and went straight to the #52. the bike really woke up with this jet. alot snappier and would lift the front end at will. the A/F screw is out 2-2.5 turns. I am thing about trying the #50 and see how that goes, but i don't wanna get it to lean. the bikes running 1000 times better than its ever run it feels like a whole new bike! :) i'm lovin it! so should I try the #50 pilot? I have the needle set in clip 1, #52 pilot jet, 178 main, and A/F srew 2 1/4ish turns out . hows this sound? any thoughts from the jetting masters? mods are listed in my first post.

Thanks
Shawn