A friend of mine (computer illeterate) recently purchased a new SuperHawk. As with all things mechanical that he owns or has ever owned he wants to start modifying it! So I have been tasked with getting some info.

Has anyone changed sprockets? He wants to gear the bike down just a little. If you have done this what size sprocket substitutions have you made? What brand sprocket did you use? Any recommendations / cautions. The goal here is to get a litle more "roll on the Throttle" grunt in top gear without the need to downshift. He wants a little less top end than the stock gearing offers but a little more snap at moderate highway speeds in top gear.

He also wants to know about something called a "Yellow Box" something related to tuning / adjusting the bikes electronics for operation after engine modifications and I suspect after gear changes. I have no idea what this thing is but I suspect it is some sort of aftermarket add on accessory???? Anyone have experience with such a thing? Any help appreciated on this I don't have much info on this "Box" gadget so any data is new data.

Lastly he tells me the bike has some sort of "water jackets" around the carbs. Something to do with emissions. Any experiences changing this system to richen up the engine a little? He seems to feel the bike is super lean...I can sure believe that in todays emissions environment....and he seems to think changing the way the carbs are warmed by the water can effect performace and driveability. This might be a simple as just shutting off the water to the carb jackets?? Again any ideas / observations appreciated.

Sorry if this is all a little vague...these new bikes are way past the technology of my CBX and my 1989 ZX-10. Any help is greatly appreciated.

He is very competent technically but I think the newness of some of this technology has him baffeled...I know I would not want to deal with it. If he gets some starting points / prelim data and warnings about what not to do from some folks with experience he can run with the ball. Apparently he cannot find any info on how to modify these subsystems.

He is particularly interested in this Yellow Box gizzmo.

Thanks in advance for your help
CBXer

 

OK. In order:
Lots of people change sprockets a little. It's probably not worth the trouble, though others might feel differently.

The "Yellow Box" is a speedo recalibrator used after gearing changes to restore proper operation. It's not a performance enhancer. It merely offers adjustable calibration of the speedo signal.

Jet kits are a good option for a little extra power. The SH responds well to them, yeilding about 5 hp.

Coolant runs through the carbs to preheat them for cold weather. Probably another mod of little benefit.

Though you didn't mention it, follow your heart. If your friend is really this novice about mods, he probably shouldn't attempt these.

 

OK, first of all, gearing speaking, the stock SH has 16T in the front and 41T in the back. I only went two up in the back and I am very satisfied. Some recommend the 1 down in the front and two up in the back, but that way low in my opinion.

Second, the SH is a carburated bike, that means there are no electronics that control any fuel mix in the engine, the only electronics that control the engine is for the ignition of the spark plugs. So there is no "yellow box" on the SH, he can put a jet kit in the carbs, which will give better throttle response and a little more hp on top. It is pretty hard to gain a lot of HP (more than 10) on the SH without major engine mods.

Third, as to the water jackets in the carbs, I don't recommend shutting off the coolant. honda engineers didn't not spend countless hours to design a carb that big for someone to come and mess with it that way. Jet kit will be the best to do on the carbs.

For emissions sake, he can close off the PAIR system on the bike by closing the opening of this system on the head covers with block off plates. Do a search on this at this forum under PAIR valve and tell your friend to start his SH education by reading more and more on this forum.
Good luck to him.

 

I have the -1 +2 sprockets and 520 chain off Ebay, (sum of all parts), I think it's a little much for the street but I love it on the track. So for the street I bought a 41 for the back. The rear sprocket is a Vortex aluminum for the track and sprocket specialest for the street, (Vortex came with the kit the other cheap on Ebay). The price was good although I had to send the first rear back, (wrong one) with no hassle and you have to cut the chain and press the master link.

As far as the yellow box the only other thing I can think of is the speedo healer,(not sure if that's the right name). It fixes the speedo reading no matter what gearing you use.

And +1 on the carbs leave 'em alone.

 

As Kyle's mom from Southpark would say, "WHA..WHA..WHAT!!"
There's a huge difference if you do enough of a change. I put mine on at the track after owning the bike for 4 1/2 years and for the first time since the day I bought the bike it almost threw me on my *** again!! It was kinda embarrassing doing a 12 'o clock wheelie on hot pit.

 

I would recommend the sprocket change, as it requires a lot less tinkering that the jetting. It's one of the first mods I make to any Superhawk I own, and I like it because I am a wheelie-holic and like to pull it up in 4th gear. A 43-tooth rear sprocket is almost always available on Ebay, as would be the 15-tooth front sprocket, if you feel extra daring. Changing the sprockets this way will undoubtedly give you a little extra punch from your throttle, but it will kill your top end speed (by about 7-10mph on the warped VTR speedo). As far as "roll on hit in top gear" I personally have rarely used 6th gear for anything more than changing the pitch of my engine and exhaust (TBR gets a little loud in the helmet!).

As for the "water jacketing", thats part of the coolant loop, and being as how its powered by the coolant pump on your engine, I don't think you would net any noticeable result from re-routing or blocking off those hoses, except maybe putting extra pressure on the rest of your cooling system.

Don't know enough about yellow boxes to tell you one way or the other, but I think it's been covered already.

P.S. - What was it like driving a 6-cylinder bike? I bet changing the exhaust headers was a pain in the @$$.