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O.K. haven't been around for awhile, here's another mod I did to my XS11(12) - which has an 1196cc motor and ported out head and other go-fast goodies such as Dynacoils, tweaked stock carbs, advanced timing, performance pipes, modded intake(drilled box, K&N), and others.. Now, I dug into my collection of various carburetors scavanged from NZ's equivalent of Ebay - that's TradeMe, over time I've I'd picked up some Gixxer 750 38mm mikunis, some ZRX11 36mm keihins, and some R6 37mm keihins. Decided to try out the 36mm's as their spacing of 75-85-75 are the closest to the XS11's 78-84-78 spacing. Means you can install them to the stock XS11 manifolds with only a small bit of tweaking.
The R6 and GSXR carbs really need alternative manifolds to fit, the Gixxer 38mm mikunis are a whopping 84.5-89.5-84.5 and the R6 37mm keihins are 75-75-75, but it's still possible to re-space them - albeit with a bit of drama involved. Anyway, with some slight dremelling of just the No1 and No4 XS manifold edges, the 36mm keihins slide in nicely
My XS manifolds have been previously slightly opened out inside to match the ported head, so all's good on that front.
Now to the XS airbox, first thing I did was pull off the crank breather hose and tear out the grungy ridiculous crank breather tubes in there. Last thing you want is hot air in ya engine intake. (should of done that years ago) Then sealed up the hole in the airbox with thick tape at the same time.
Now, the ZRX keihins have all sorts of bells and whistles tied into the usual annoying twisting conglomeration of tubes and emission control gadgets, they have the sync ports on the carbs themselves rather than on the manifolds too. Ditched the emission gadgets and connected by hose No1 port to No4 and No3 to No 2 for the 'YICS' effect a la XJ's etc...
Also ran the the XS vac advance from manifold 1 via a tiny 1/2 mm connection as per the stock XS setup. Ran the keihins' bowl breathers to the XS airbox as per XS, and rigged a T fuel connection from both XS petcocks to the keihins single large fuel hose setup. Also butchered an XS throttle cable system to fit, and even rigged an XS choke lever to the side of No1 carb. The ZRX's t.p.s(digital timing gadget) sits unused, but hey, it still LOOKS important though!
Right then! These modern carbs are an improvement over the poor old 28 years of age BS34's, the low circuits are improved and more refined and the slide components are smaller, lighter, faster! They've got the 'shut throttle enricheners' - small diaphragms that seal up the air jets by vaccuum on the over-run. No popping on deceleration and quick response when back on the gas from closed.
I modded the carb internals somewhat too, eg- snipped the slide springs 1/2 inch and drilled the slide vac holes slightly in conjunction, also shimmed the stock unadjustable ZRX needles up 2 washers(1mm). Left the floats at 18mm. Running keihin 38 pilots and 130 mains. Then had to elongate the 3 XS airbox bolt connections to bring the airbox closer to the slightly shorter keihins.
O.K then,got everything I could think of sorted - then came crunch time. Primed the carbs and hit the starter. Fired instantly and settled to a low smooth idle. Great! Plug and play, yeah.
Rushed inside and grabbed a helmet and gloves, and went for a blast. The good news kept getting better, increased response, smoothness and power was REAL. No more niggly buzzing at 3 grand either. These light modern CV semi-flat slides made the poor old clunky BS34 CV round slides feel like sluggish chunks of lead in comparison.
Opened her out on the nearest empty road(5 minutes from home) - and hit a true 210kph EASILY. Cracking the throttle wide open at 170kph, she fair rips forward in acceleration. Real buzz! Did a plug chop at the ton, and another at legal speeds, all fine. Rumbles along strongly at 2 grand in 5th, smooth as silk, and still instant response at the slightest touch of throttle.
The huge velocity stacks in the stock XS airbox are a real asset there, you always hear the 'experts' telling ya that going up in size on carbs will weaken the bottom end torque. Ha!! Not on the XS anyway! Certainly won't be bothering with pod filters, as the power kicks in hard with the 36mm carbs/Xs aibox as is.
Next mod is to rig a pair of alloy brake caliper brackets to fit some fireblade 4-pot calipers to the XS forks. Will post some picks of that one later. Cheers.
The R6 and GSXR carbs really need alternative manifolds to fit, the Gixxer 38mm mikunis are a whopping 84.5-89.5-84.5 and the R6 37mm keihins are 75-75-75, but it's still possible to re-space them - albeit with a bit of drama involved. Anyway, with some slight dremelling of just the No1 and No4 XS manifold edges, the 36mm keihins slide in nicely
My XS manifolds have been previously slightly opened out inside to match the ported head, so all's good on that front.Now to the XS airbox, first thing I did was pull off the crank breather hose and tear out the grungy ridiculous crank breather tubes in there. Last thing you want is hot air in ya engine intake. (should of done that years ago) Then sealed up the hole in the airbox with thick tape at the same time.
Now, the ZRX keihins have all sorts of bells and whistles tied into the usual annoying twisting conglomeration of tubes and emission control gadgets, they have the sync ports on the carbs themselves rather than on the manifolds too. Ditched the emission gadgets and connected by hose No1 port to No4 and No3 to No 2 for the 'YICS' effect a la XJ's etc...
Also ran the the XS vac advance from manifold 1 via a tiny 1/2 mm connection as per the stock XS setup. Ran the keihins' bowl breathers to the XS airbox as per XS, and rigged a T fuel connection from both XS petcocks to the keihins single large fuel hose setup. Also butchered an XS throttle cable system to fit, and even rigged an XS choke lever to the side of No1 carb. The ZRX's t.p.s(digital timing gadget) sits unused, but hey, it still LOOKS important though!
Right then! These modern carbs are an improvement over the poor old 28 years of age BS34's, the low circuits are improved and more refined and the slide components are smaller, lighter, faster! They've got the 'shut throttle enricheners' - small diaphragms that seal up the air jets by vaccuum on the over-run. No popping on deceleration and quick response when back on the gas from closed.
I modded the carb internals somewhat too, eg- snipped the slide springs 1/2 inch and drilled the slide vac holes slightly in conjunction, also shimmed the stock unadjustable ZRX needles up 2 washers(1mm). Left the floats at 18mm. Running keihin 38 pilots and 130 mains. Then had to elongate the 3 XS airbox bolt connections to bring the airbox closer to the slightly shorter keihins.
O.K then,got everything I could think of sorted - then came crunch time. Primed the carbs and hit the starter. Fired instantly and settled to a low smooth idle. Great! Plug and play, yeah.
Rushed inside and grabbed a helmet and gloves, and went for a blast. The good news kept getting better, increased response, smoothness and power was REAL. No more niggly buzzing at 3 grand either. These light modern CV semi-flat slides made the poor old clunky BS34 CV round slides feel like sluggish chunks of lead in comparison.
Opened her out on the nearest empty road(5 minutes from home) - and hit a true 210kph EASILY. Cracking the throttle wide open at 170kph, she fair rips forward in acceleration. Real buzz! Did a plug chop at the ton, and another at legal speeds, all fine. Rumbles along strongly at 2 grand in 5th, smooth as silk, and still instant response at the slightest touch of throttle.
The huge velocity stacks in the stock XS airbox are a real asset there, you always hear the 'experts' telling ya that going up in size on carbs will weaken the bottom end torque. Ha!! Not on the XS anyway! Certainly won't be bothering with pod filters, as the power kicks in hard with the 36mm carbs/Xs aibox as is.
Next mod is to rig a pair of alloy brake caliper brackets to fit some fireblade 4-pot calipers to the XS forks. Will post some picks of that one later. Cheers.
Wait, you have replaced the calipers, haven't you?
My 'dynos' are deserted roads
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