PWK jetting starting point on 250lc

[jimmyg]

My brothers 250lc is getting to the point of starting now, so thought I would ask if anyone has used pwk28's on a 250lc and what jetting they run, its standard barrels with tyga pipes the jets that came with the carbs are pilot 38 mains 135, he wants to know if that's a good starting point or what is? And if we have to order jets what sort of range would be a good place to start to save having to wait for the post for each set
cherers jimmy

[abar121]

I'm no expert on these, only had one bike with PWKs, your mains might be too big, if you are keeping the airbox. Pilots might be about right, KR1s run 38s I believe. If you still the airbox on, I'd give it a go as it is.

I'd probably stick with the stock carbs on an untuned 250 to be honest. Or get a 370cc conversion on the top end

[jimmyg]

Thanks for your advice.
My original carbs are very early type & are
Buggered.
I am 3 months into the six month wait on the
370 conversion.

[dusty350]

The jets you mention are the generic sizes the carbs come with. I put new Pwk's on my 400e hybrid, but got Mutts to dial them in on the dyno - it's the only safe way of doing it I think. He went down on the mains and up on the pilots - the carbs were very rich "out of the box", and the resulting flat spot that started around 4k was ironed out with Dave's expert help. Jets aren't cheap, so save yourself the time and hassle and book a sesh with "Dyno Dave Whattam"

Dusty

[Tobyjugs]

I have just changed my engine from a standard 250cc 4L1 to a 400cc YPVS engine. The pipes were changed from Jim Lomas to bespoke pipes for that engine The rest such as reeds and air filters stayed the same.

I only changed the pilot jet up one size from 50 to 52. To my surprise no other changes were needed. I must also add my 250 engine was jetted for cold winter conditions

If someone has a 350 cc engine with the same sort of parts such as reed and air filters you will be in the neighbour hood.