Jetting Problems on my 30mm OKO
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Blaner
Your Friendly South African Ambassador
ok, leak test is your primary task, the reed boots leak like you wont believe, you need that motor sealed tight!
make sure the top cap of the carb is also sealed, i made a rubber gasket instead of that fibre one as it was sucking air thru the top
make sure the top cap of the carb is also sealed, i made a rubber gasket instead of that fibre one as it was sucking air thru the top
Ok so this is where I am at now. I changed the main jet to the 152 and it was hard to tell but I think it got worse. Everyone has been say that I am running rich but I dont think so and this is why. When the bike runs rich it 4 strokes and in my case it does not feel like that at all and why does it not give me the problem in the low gears?
It really feels like the bowl is running dry because its like there is suddenly just no fuel. Someone told me that I might have the wrong needle any thoughts on that? I am going to change my float hight like Slick says did not really want to do that because its a brand new carb and should be right from CPW? I am scared I was measuring from the wrong place hope I dont make it worse.
Blaner I want to do the leak test but dont have the gear for that and was told that if the motor was leaking it would show signs like the revs would hang but the bike real runs nice, just on WOT in 5th and 6th is where the problem is.
It really feels like the bowl is running dry because its like there is suddenly just no fuel. Someone told me that I might have the wrong needle any thoughts on that? I am going to change my float hight like Slick says did not really want to do that because its a brand new carb and should be right from CPW? I am scared I was measuring from the wrong place hope I dont make it worse.
Blaner I want to do the leak test but dont have the gear for that and was told that if the motor was leaking it would show signs like the revs would hang but the bike real runs nice, just on WOT in 5th and 6th is where the problem is.
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Should be but the 30mm I had was off by 3mm. adjust the float, first put that 160 back in, take it for a spin! I don't think the needle has anything to do with your problem, but I have been wrong before!
Blaner
Your Friendly South African Ambassador
that right there is a problem...dont assume ANYTHING, you are assuming a air leak will cause erratic idle etc and you are right but that is only with severe leaks, chances are you have a leak and it could be effecting things without your knowledge.
make your own leak tester, i used a pool pump pressure gauge. the rese of the bits just shop around 4 untill you get something together.
I also know what you mean when leaning out makes it worse, my problem exactly. mine runs well WOT with a 168 and could probably run with a 170 if i tried.
Needle is where my problems lie tho. the stock OKO needle which is an N80F is totally useless for me, all clips it fails. the banshee needle works on the richest clip
The following is an extract from an email dicussion i had with my Brother when we were figuring out this needle story:
if you want needles from yamaha , ask for the YZ85 needles:
All the 85’s running the PWK28 use the N-series needles, but these seem to be twin and triple taper needles, explains why the those little bikes have such a ‘hit’ when power comes in… The single taper Keihin JJH etc provide a smoother hit….
Read:
2008 YZ85 Jetting - ThumperTalk
DirtRider.Net Text Version - needle ?
N-series needles are decoded as such (similar to Keihin JJH etc codes) Here’s NAPF for eg:
N = series
A = taper (a – z leanest to richest)
P = length (a –z shortest to longest [rich to lean])
F = diameter (a –z richest to leanest)
So NAPF has a leaner taper and length, but same diameter as the NBKF (stock YZ)
“So to reiterate, change out the needle's diameter for 1/16 to 1/4 throttle, move the clip up/down for 1/4 to 1/2 throttle. ANd go w/ a straight taper needle if you want to tone down the MX hit.”
Here’s Yamaha YZ part numbers as well if you interested (richest to leanest):
· 5PA-14916-KE-00 NEEDLE (NBKE)
· 5PA-14916-KF-00 NEEDLE (NBKF)
· 5PA-14916-KG-00 NEEDLE (NBKG)
· 5PA-14916-LE-00 NEEDLE (NBLE)
· 5PA-14916-LF-00 NEEDLE (NBLF)
· 5PA-14916-LG-00 NEEDLE (NBLG)
Here’s the Kawa numbers too:
· 16187A: NEEDLE-JET,NAPD
· 16187B: NEEDLE-JET,NAPE
· 16187C: NEEDLE-JET,NAPF
· 16187D: NEEDLE-JET,NAPG
· 16187E: NEEDLE-JET,NAQC
· 16187F: NEEDLE-JET,NAQD
· 16187G: NEEDLE-JET,NAQE
· 16187H: NEEDLE-JET,NAQF
· 16187I: NEEDLE-JET,NAQG
OKO comes std with a N80f (aka N68a) needle, Keihin needle code for that equates to a JJH (1st letter=taper, 2nd=length, 3rd=diameter). Saw a couple posts where guys move to a GJH - leaner taper...
carb jetting/needles for keihin 28mm - SIP Scootershop Community
Need HELP Jetting 30mm OKO carbs - Banshee HQ Forums
pwk needles - Banshee HQ Forums
LCGB Forums :: View topic - PWK carbs
Yamaha Blaster Forum - View Single Post - airbox and OKO carb. (this one is interesting!)
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Thanks for the help guys! Going to set the float hight tomorrow and put the 160 back. Then Monday I am going to see about making a leak down tester.
If ya can't find all the parts for a tester let me know I sell them and can work with ya to get it to S.A.! I:I But definetly do one of these tests.
Thanks for the help guys but I have sorted the problem out. It was my float level, it was out by -+5mm. I set that right and the bike had no more problems in 5th and 6th on WOT. It almost felt like it was pulling better in the other gears to.
I did the plug chop with 160 main and 48 pilot in and attached a photo of the plug. What do you guys think of the colour?
Still what to do the leak test to make 100% sure everything is cool.
I did the plug chop with 160 main and 48 pilot in and attached a photo of the plug. What do you guys think of the colour?
Still what to do the leak test to make 100% sure everything is cool.
Attachments
Cant tell the colour, because the threaded section is hiding the porcelain insulator, you have to chop off the threaded bit, hence the term "plug chop"
Cut if off and repost pic so the smoke ring can be seen.
Make sure you do a leak down test before you ride it again, be cause if it is leaking it will affect the results of a plug chop.
After passing leak test do a WOT in 5 or 6 with a new B8ES and then plug chop.
Blaner
Your Friendly South African Ambassador
you set it to 19mm from sealing surface to top/bottom edge of float? what was the initial measurement?
glad you making progress!
glad you making progress!
Thanks Blaner! Yes I set it to 19mm and it was about +-24mm.
Thanks Blaaster will chop the plug and repost the photo
Ok I have attached two photos of the chopped plug. One with the flash and one in sunlight. This is for the main jet still have to do the needle.
From what I have read on
Plug reading....
This is on the rich side? How I understand it, the ring should be brown. Before I try a smaller jet should I do the run again and hold it for longer then 10s @ WOT in 6th with the 160 main? My next size down is a 152.
From what I have read on
Plug reading....
This is on the rich side? How I understand it, the ring should be brown. Before I try a smaller jet should I do the run again and hold it for longer then 10s @ WOT in 6th with the 160 main? My next size down is a 152.
Attachments
Yes that is on the rich side, I think u should try the 152 do the same thing, and see. Glad ya got that float where it needs to be! -slick
