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Post by abar121 on Jul 19, 2021 15:05:11 GMT 1
Chaps,
My YPVS with 28mm KX 85 PWKs, won't pull past 5-6k when under load. It's crisp enough just off idle, ticks over well, pulls away fine and will rev right up fine in neutral.
It's like it's running super rich at that point and just refuses to pull past 6k at any throttle opening. Thinking it would be the needle jet, I moved the clip up one position, wound the idle mixture screws out from 1.5 to 2.5 turns. Zero difference. I can't ride it far enough like that to get any decent plug reading.
F1 with Mick Abbey mild road tune, stock pipes, airbox with filter, snorkle removed. 135 mains, JJH needles, 40 pilots.
I have a set of Higgspeed and also Polini pipes to try, but it's so far out as it is. Is anyone else running PWKs and stock pipes on a YPVS? I was thinking of trying 128 mains, but I doubt it's getting on them as yet? Or running with airbox lid off etc.
One of the carbs came with a needle that was quite a bit shorter than the other. JJH needles are now fitted, but I'm wondering if there is something non-standard about the seat in that carb.
Cheers.
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Post by bare on Jul 19, 2021 15:18:13 GMT 1
Carbs bought new from a Kawasaki source.. and in a Kawasaki box  IF not bought new (or Fakes:-) 'anything' could be wrong. Float valves any good ? as a guess. I use 130 mains 40 pilots jjh needles..and My 350 runs perfectly, as in it couldn't be better. Albeit a wee bit rich, by intention tho. |
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Post by abar121 on Jul 19, 2021 15:29:19 GMT 1
They are genuine PWKs with the stampings, correct serial numbers and from a trusted source.
All the jets I removed looked gen and stamped, although I have replaced them all anyway, from Allens.
One of the float valves doesn't seem to have much of a spring to it. But then I'm used to the stock Mukini's. I guess I can try replacing them.
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Post by midlifecrisisrd on Jul 19, 2021 17:14:46 GMT 1
Your pilot and main are too large
Usually with a tune and pipes but using the airbox it's around 38/135 and JJH needle with 3.5 slide
I'm down on a 35 and still rich at the bottom
Try 36 and 132's
Steve
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Post by jessy03 on Jul 19, 2021 17:47:34 GMT 1
Well mine wouldn’t run on any of the above, have tried.
Mines on 45 pilot, 138 main, jjh needle in the middle.
My spec is -
TSA pipes
Gutted and drilled airbox
Squish 0.9
Zeeltronic small amount of advance over the 31k curve at low revs.
Runs perfect, I can’t see it running any better.
Jess
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Post by tony2stroke on Jul 19, 2021 19:13:39 GMT 1
I would advise that you only change 1 thing at a time, ie raise or lower needle but leave air jet alone, or vice versa, if the spring is weak on the float valve, change it or the float height will be out, if you change more than 1 thing at a time, you will be chasing your tail trying to find what the problem is.
I was told to always start at the air screw setting, then the pilot jet, then the throttle valve cutaway (but very rare to need anything doing there) then the needle jet, then the main jet, this way has never let me down (yet)
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Post by abar121 on Jul 19, 2021 21:05:59 GMT 1
Thanks for the comments.
I'm struggling as I thought the pilot would only affect the initial throttle opening, which seems fine. Does it really impact part throttle / mid revs? It's not a slight stumble, it just won't pull from 5k at all.
I'll get some 35s and 132s. I'm on 3.5 slides.
One thing at a time, agreed. Might give no airbox lid ago to start with and see what happens.
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Post by midlifecrisisrd on Jul 19, 2021 21:19:10 GMT 1
On the pwk the pilot affects the whole rev range
Deffo take the airbox lid off and see how it is
Mine is tuned stroked motor with v4's, TSA's, airbox, trumpets out and lid drilled to death
Steve
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Post by bare on Jul 20, 2021 1:13:50 GMT 1
Why so much variation ? Keihins are Dead easy to setup.
Close is often Far better than precise on Mikunis.
~ 128 mains is into Track only Plug Chop territory.
Too edge of imminent destruction for less than dedicated Race use.
Mine though IS ported / tuned / high flow lidless airbox filter, with Pipes , Zeel ignition and PV setup.. opens Wide V early (5.5K) and stays that way till rev limiter at 9500.
NO stumbles / missfires / hiccups... Ever.
All the way to the limiter Regardless of how ineptly and when I WOT the thing.
Might not be entirely a carbs issue :-) Fuel flowing fast enough into your carbs ??
Likely it's the mechanical bits not performing well.. as observation
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Post by bare on Jul 20, 2021 1:15:17 GMT 1
double entry bungle
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Post by abar121 on Aug 16, 2021 16:50:07 GMT 1
Just to wrap this one up, I tried 130 mains and the airbox lid removed. Needle still up one notch.
It goes like a b'stard. So I guess I'll get the hole saw out.
No flat spots. Now to fit the Ignitech and take it to the dyno for tuning.
I'm near Milton Keynes, so was thinking of going to Krazy Katt. Any other recommendations?
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