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

[busted480]

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.

 

[2 strokes for life]

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.

 

[480 mike]

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

 

[busted480]

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!

 

[whenfoxforks-ruled]

Material was removed from that cylinder, it may NEVER run correctly.

 

[busted480]

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

 

[480 mike]

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

 

[whenfoxforks-ruled]

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.

 

[2 strokes for life]

Mabe try moving the clip up a position and 2 sizes smaller pilot jet.

 

[busted480]

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

 

[2 strokes for life]

busted480, i am more of a mikuni gut liking the flatside more then any carb out there for a 2 stroke.

 

[busted480]

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

 

[2 strokes for life]

busted480, if its not broken dont bother fixing it. If it runs to where you like it keep it that way.

 

[whenfoxforks-ruled]

The clip is on the top, try and find a leaner needle. Definitely try the 50. Do not worry about the mods, do what the motor tells you to do. after you get the pilot and needle where you want then check the plug after a wot chop. http://dirtrider.net/forums3/showthread.php?t=92818

 

[busted480]

The clip is on the top, try and find a leaner needle. http://dirtrider.net/forums3/showthread.php?t=92818

this was actually one of the reasons for maybe getting the pwk 38. I'm not sure if anyone makes needles for this OLD carb. its a keihin PE. if ya know of a place I might be able to find one, let me know.

Thanks for your time!

Shawn

 

[whenfoxforks-ruled]

Did you try sudco? http://www.sudco.com/

 

[busted480]

i haven't called sudco, I did look around their site. but i'm not sure exactly what i'm looking for. and theres alot of info there. i guess I need to call them. on another note, I tried the #50 pilot. the bike ran real strong through out the day. 2 1/4 turns on the A/F screw did the trick in the colder morning. in the afternoon i had to turn the A/F screw out 3 turns. should I try the #48 pilot? I don't want to go too lean though.the bike did run great with both configureations. however in the afternoon after the bike had sat for an hour or two, it was harder to start than usual. i had to choke it and kick it 5 or 10 times to fire it up. usually i choke it and it fires first or second kick. and when I killed it it backfired out the rear. it hasn't backfired since i replaced the crank seal. any thoughts? it seems the closer to perfect jetting I get its doing some unusual things.

 

[whenfoxforks-ruled]

The engine is still running fat, a long way from optimal, try the leaner jet! Could this be the area affected by porting work? You have to listen to the motor, no 2 are the same jetting wise. personally, if you have to change more than a couple sizes from stock, there is a reason going on. If and when you get lean it will run crappy and erratic, and it should not hurt the motor, unless you go and race a long endurance race. Starting issues are usually the starter circuit, and, or float valve. A 75 is the stock pilot?

 

[busted480]

stock jetting on the bike is:
180 main
72 pilot
28G needle on third clip
A/F screw 2 turns out
float 22.5mm

right now I'm running:
178 main
50 pilot
28G needle first clip
A/F screw 2 1/2 turns out
float is adjusted correctly

Thanks for your help!

Shawn