I have never gone up on pilot size and on my current ride I went down from
17.5 to 15 pilots. But that may be more because of my style of porting and
that Its a big bore, piped and can and aftermarket head.
One other difference I have always run the Boyeson original style power reeds.
They are the duel petal inexpensive reeds. The top reed opens first with the second
reed underneath staying shut until mid range rpm, that bottom reed has a hole through
it for low rpm flow. The smaller hole makes for higher air speed flow at starting and low rpm,
giving better fuel atomization.
I just came in from starting mod sled at 17 below with a 15 pilot, 3 pulls and the first was just getting
it turn over. Road it out of the shed in under a minute, no problems.
We have the same engine, mines a 08 XP 500SS with the 4" long intakes so mine should really be screwed up
compared to yours with the short intakes. I'd give anything to put your short intakes on mine because of better air bottom to top air flue and fuel atomization, instant 5HP or more if it was possible.
Pilot jets really plug up easy and difficult to clean because they are so small, better to put in a new set. Other option is run a real strong carb cleaning dose of Sea Foam in the gas through carbs, it might help.
Number of years ago I bought a used Yami 4 stroke dirt bike. Completely went through the carb, took all jets
out and cleaned them, blasted all orifices with carb cleaner and it ran great. Then some time later I did the Sea Foam carb cleaning dose on it and had to turn the idle speed down because it picked up so much rpm
afterwards. I'd also recommend the Boyeson power reeds.
Also check your compression to see healthy that seems.
