Pwk jetting where to start ?

[miker1bike]

Just got hold of some genuine pwk 28mm carbs for my 350lc ypvs hybrid

Question is where do I start with the jetting will run autolube as have already sorted the nozzles for 2stoke oil

Current specs which are working pretty well

350 f2 engine
1.5mm oversize bores
Mild tuning to inlets and transfers but not exhaust ports
Unknown race pipes but they have a really fat belly have been told are top end pipes
Stock 31k carbs
Stock air box with snorkel removed and a few holes drilled in the lid
Current jetting is stock pilots and 280 main jets

Anyone know what the equivalent kehlin main jet is to a mikuni 280 jet

Or any idea what jetting to start with without having to buy loads of different jets ?

[rich]

To be honest stock KR1/KR1S settings work very well and they should have 135 mains stock. If you were running foam pod filters then you would be looking at approx 150 or 152.5 mains so as you have a slightly modded airbox I would suggest starting at somewhere in the middle like 145 and plug chop it.

[Dieseldog]

Mine is very similar to yours, although the engine is oem tune, Mick abbey pipes with snorkel removed & drilled air box lid, 28PWK's with oil lub injection.

I started with 142's which is close to what Rich is suggesting but found it was way to rich at the top, slowly reduced to 138's

Just been on dyno at Mick Abbeys see here.

Was running 138 mains, 38 pilots when I went to see Mick, main jets now 130's, pilots are 35's. still running slightly rich at the top end but didn't have any smaller mains to try out & slightly weak at the bottom.

Also got some JJH needles to try (but these are richer at the top end & weaker at the bottom)  might try them when I visit him again with some smaller mains (I've just got) and larger pilots.

Good starting point will probably be the standard 135 mains and 35 pilots.

HTH

[midlifecrisisrd]

Mine has tuned stroked motor, tsa pipes, v4 reeds, and air box as yours.

Running 36 pilot and 140 mains

Should really be running 35 pilot as air screws 2 turns out. Was lean at top end with 135 mains and tzr reeds

Steve