if you stay with the same sprag clutch on the low bhp model
You can fit the high lift cams from the higher bhp model
timing is same on cam chain.
you would be advised to advance the spark on the timing side about 3 deg
do this by fileing away them 2 little bosses to advance,
you can stay with the same cdi as you havent changed your sprag clutch(should make sense to advanced members)
get rid of that air box and fit foam bellmouths ram air not i repeat not them chrome jap shit ones HAVE A LOOK ON EBAY 52 MM RAM AIR OR EQUIVALENT.
Carbs yes those bloody carbs will need re jetting 2 turns out on air screws
now you standard jets are as follows mains 100 and pilots 47.5
Change both of these to ......pilots 52.5 and main jets 120 guy in liverpool sells all you need just google it you will find it under makuni carbs.
the above will give you a slight very slight over rich mixture you dont want to be lean on this and try it out adjust accordingly but this is your starter for 10
AND DONT FORGET ALL THOSE SEALS ON THE CARBS I HOPE U BOUGHT ALL NEW. (theirs a good boy)
my engine the head i have stage 1gas flowed so u might be a bit different on jets. you might need to go up or down 1 depending on this
HOPE THIS IS OF USE (HONDA HONDA MY KINGDOM FOR A HONDA!!!!!!)lol I love the bike realy their is always something going wrong in the month

Here's my tuppence worth on this subject if you want to retain the stock airbox but fit a washable K & N filter kit, ( Pt. No. SU-7592 ), that replaces the stock, one use only paper element. (I've fitted the larger of the two intake rings to my K & N filter).

My 1990 GK76 has a bone stock, pre 1993 (59 hp) engine, ignition system & sprag clutch fitted, but I've also slotted the ignition pick-up's holes to advance the ignition timing 2-3 degrees. It also has a full stainless steel exhaust system fitted.
(Sandy Bike Spares, now BlackWidow, downpipes, R6 linkpipe & an old, 300 mm long, round section Scorpion end-can).
The jetting & settings on mine are very similar to Minkathecat's above.

The pilot jets (as they're called in the MIKUNI carb. parts book) are the stock #15's.

The mixture screw's are set at 2 turns out, up from the stock 1.5 turns out.
(I tried 2.5 turns out but it was too rich. The rev's would dip when throttle blipped from idle rpm when engine was up to temp.).

Tha float heights are set at 20.0 mm's, measured from the gasket faces to the highest point of the floats with the float valves just closed.

The mid-range "Power Jet's" (as they're called in the MIKUNI parts book) are currently up from the stock #47.5's to #52.5's, BUT, having rode my bike yesterday for the first time since fitting the 52.5's, (did 65 miles), it still stutters/hesitates if the throttle is cracked open suddenly between 4 & 7 thou., so I'll be trying #55's to try & cure this!
If the throttle is rolled open tho', it pulls through this part of the rev range better than before.

The needle jets are brand new, stock O-5's & the needle's are brand new, stock 5DJ05's with the clip's set in the fourth from top slots. Main jet's are currently #120's, but may require changing after a dyno run to check the fuel/air ratio.

Oh !!! And most important of all, my R model (non SP) carb's have had BOTH sets of LITE TEK's excellent Viton rubber seals & gasket kits fitted BEFORE I started messing about with jets, needle's & settings!

Hope this helps anyone new / inexperienced wi' these wee beasties.

Edited to include float height on 21st April 2016.