K and N air filter/Jetting.

[jjwaller]

Finally got the Big Dog up and running again.
Too much travel and not enough storage maintenance.
Redid the carbs and re-jetted with 47.5's pilots.
Bike has never run better. It is wonderful now. (Damn I hate the new "Gas"!)
Think it needed the additional jets even before due to the crappy Mac 4-2 exhaust. Question is, I just ordered a K+N standard filter for stock airbox.
I know on my original CB750, back in the day, a little more jetting sure helped.
Do the XS11's need more with the introduction of a K+N??
Carbs and airbox (Not to mention rest of the bike, except FD) are stock.
Thanks

[dbeardslee]

Depends. What size mains, and what other mods are you running?

[jjwaller]

As I said, stock. 137.5 mains
Stock airbox.
Mac 4-2. (Until I can find a real exhaust)
Only running mod is the new 47.5 pilots. Old were 42.5 stock.
Just wondering what to expect with a stock style K+N air filter.

[dbeardslee]

Sorry - should have read more closely. Anyway, your bumping your pilots when what you should probably bump is the mains. You might want to take a look at the jetting recommendations in tech tips - I've found them to be pretty accurate. On your setup it suggests 1 jet size for the 4/2, 1 jet size for the K&N, and subtract 1 which would give you 140 mains, and 45 pilots Stock pilots on a 78E are 45's not 42.5's according to the fiche. If it was me I'd drill the airbox and go with 142.5 mains and 45 pilots. It's also a good idea to stick with genuine mikuni jets. They vary from manufacturer to manufacturer in terms of size - one mfg's 142.5 is not necessarily the same as another mfg's. Mike XS has them for $6 a pair, and they have both the mains and the pilots. Here's another good reference for you - CV Carb Tuning Procedures.