Hey Everyone,

I think my bike is finally coming together. Got the vacuum fitting for the front cylinder so I could get a proper carb sync done, bike seems to be smoother.

I've heard this from other people too, that the hawk doesn't pull smoothly below 3000 rpms with much more than half throttle - feels like the engine is struggling. I did the TPS mod - it may have helped *slightly*, hard to say.

What else can you do to smooth out the engine in this range? My Ninja 650R had the exact same behavior, and the shop adjusted the TPS on that, and now it pulls beautifully at full throttle down as low as 2200 RPMS.

I've read here that some people run larger than stock pilot jets - what is the benefit of that? Would it help with this? How about that funny "pilot screw" that I don't have a tool for? Is that sitting there begging me to turn it in hopes of getting a richer mixture at low RPMs?

 

You got to let us know your mods. A well sorted Shawk handles 2000 rpm no problem (at least mine does). Mine is dyno jetted with microns - can't tell you the settings as it was done by PO. I can tell you when I tried the K&N with no changes to the jetting my sub 3000 rpm went to hell.
My point is perhaps fiddling with your jetting might be helpful, but let us know some more back ground

 

Sorry - my bike is *BONE* stock except for the TPS mod that I already mentioned, so it didn't occur to me to list the non-existent mods. Basically the only interesting info is that the bike had only 945 miles when I bought it, but it had been sitting for almost 2 years w/out having been properly prepped for storage.

As a result, it didn't start at first, so I overhauled the carbs myself. Actually that didn't work out very well, I apparently didn't get them clean enough, so I bought a spare carb set from IndieRocker, and replaced his jets, needle & slider with mine b/c his was modded. I really want to believe I cleaned my jets well enough, but I don't really know how to know for sure, short of just putting brand new jets in.

At this point, the bike starts very well, usually immediately, sometimes it takes a bout a second of turning over. I believe I have the carbs perfectly synced, although I've used a homemade gauge. I have a pro gauge on order just to be sure.

There is one or possibly two small problems that I have yet to diagnose, besides the being rough <3k + >50% throttle: There is still a very occasional "clunk" that feels like metal contacting metal - I can feel it in the frame. It's minor, and infrequent, I can ride 20 minutes without it happening. However the one time it happens almost reliably is when starting either cold or with a weak battery, if the engine is turning over really slowly, often it will happen and the engine will stop turning over even on the starter. I don't know what it is, but since it is so infrequent, I'm guessing it's not related to the trouble below 3k.

The other "problem" is I still get occasional misfires - sneezes or mini backfires. Frequency varies, but usually once in 5 minutes. If I happen to be idling when this happens, the engine stops. If I'm moving, momentum carries me through it. Whatever the cause of this is, it seems like it could certainly also contribute to the less-than-perfect running below 3k. FWIW, this does also seem to be triggered by blipping the throttle to downshift, but still only occasionally.

 

what did you set the TPS at? Most of us have got rid of restrictive parts that choke things up a bit as you can tell from the bike descriptions like mine at the bottom of this post. Makes a huge difference in terms of reducing, eliminating the symptoms you describe.

 

search for shimming needles...

my bike did the exact same thing as yours

rough running below 3K, surging...mini backfires...they are all attributed to too lean condition. thank the Honda team for trying to make the bike as emissions friendly as possible. even had the DJ Stage I kit installed when i installed the Yoshis and the shop didnt do it right...they tuned the top end just right but too lean at the bottom. raised the needles one position and the problems went away. but i think the bikes a bit too rich top end.

 

I set it as low as it would go w/out cutting the sensor mount itself. I think it read around 600 ohms. My hookup was sloppy, I couldn't get a really stable reading b/c I didn't have proper connectors.

I'm really torn on removing the PAIR. I hate the friggin' thing, it is always in the way, and I hate the popping mini-backfires. But I'm afraid I appreciate it's purpose, and don't want to go pumping the atmosphere full of unburned fuel.

I'm going to look into shimming next.

Thanks for the input all.

 

I set it as low as it would go w/out cutting the sensor mount itself. I think it read around 600 ohms. My hookup was sloppy, I couldn't get a really stable reading b/c I didn't have proper connectors.

I'm really torn on removing the PAIR. I hate the friggin' thing, it is always in the way, and I hate the popping mini-backfires. But I'm afraid I appreciate it's purpose, and don't want to go pumping the atmosphere full of unburned fuel.

I'm going to look into shimming next.

Thanks for the input all.

 

I know it's difficult to get a measurement by yourself, for me too.

The TPS most likely needs to be turned beyond where it stops and that's why I turned it further and drilled a hole and screwed a sheet metal screw in to hold it in that position. It was quite a bit further than the adjustment slots to get it to the correct position. Once I got to the correct position, I marked it and turned it back and forth a few times and you can feel that it's right, as it's loading the spring. I think i could simply do it by feel and get it right now. If you don't want to drill there's another, probably better, way that I learned about after i already drilled. No biggy, it works. Search and you'll find it, but I'll bet if you go back in there and turn it further, you feel what I'm describing and you can tell you're affecting the adjustment enough, and you'll be happy with the results.

 

I know how you feel about the environment, but i don't think that little ole you or me is going to make that big of a difference in terms of uncorking your hawk a wee bit. Especially when our country is bombing the **** out things and generally polluting everything with tanks, planes, ships and who knows what. Get that **** off there and put a big smile on your face. Enjoy the character of the Superhawk, the sound, torque, vibration and that front end gettin light when you twist that big twin up.

 

Can you say Flo Commander?

 

Weeeellllll... I'm with you except of the part where if I understand correctly, PAIR has no effect on performance - it's just burning off unburned fuel in the exhaust... so as much as I hate that friggin' valve being in the way and the sound it makes, I'd be more likely to relocate it than remove it.

 

Our bikes are very rough if lugged under 3500 RPM, ignition advance need to be pulled like crazy to make it bearable, but will still be rough, premium fuel helps there since it burns slower, it's the chemical equivalent of retarding the timing
The engine internals are pretty light since the bike is intended to spin to 9500 RPM and quickly accelerate, a 500 CC jug is hard to compress when full of air/fuel so it decelerate the engine and then the big kaboom does the opposite, so I think that the rough running you describe is the normal behavior of the bike if I understand it right.
The only fix I see is a heavier flywheel, but accelerations will suffer.
As for the coasting backfires, just shim the needles as said above.

 

Well... Since it actually simulates a airleak when it activates, yes it does... You loose a bit of RPM and momentum and need to gain that back...

If you look at a dyno run with a stock bike you can clearly see the dips where the pair activates...

 

I take exception to "very rough" - We don't have inline 4s, but my bike doesn't "lug" under 3.5k. I have to get sub 2k before I get lugging.
My experience is properly jetted our bikes will accelerate smoothly from 2k on up, whether part throttle or full.
My TPS is set at minimum adjustment w/o modifying ~580 or so. The only thing I noticed when I lowered the TPS was the ability to idle smoothly at 1000rpm verses the 12 - 1300 I used to keep it at.

 

avramd at this point you have a few options...

1. Take it to a shop, pay them to put it on a dyno and jet it... To get both high and low speed setup rigth on a VTR you need a guy with experience with this bike... Otherwise you will get one or the other...

2. DIY... That means ripping apart and setting/shimming/exhanging the carb parts 10-20 times...

3. Do nothing... Keep it above 3000 and gain mileage... Anything below 2500 is lugging it and decreases mileage even when jetted properly...

4. Buy a FloCommander and you should be able to have as good a setup as you get with the DIY option in less than a third of the time and number of repetitions... And you can then make adjustments easily later... do a search and you'll find good write-ups on it... I'm to lazy to repeat myself...

 

tweety is right if you want to do it right. Due to financial constraints, I just did what I wrote previously in addition to what's listed below and no misses, roughness, backfiring, or other difficulties. Runs strong all the way up to max rpms.

 

I'd say on most VTR's that have the jetting correct it will get noticable at around 2000 or just above... All below 2500 or so is noticable in the gas tank, but not really "lugging" it in terms of how the bike feels...

 

+1
My only point was there should not be surging, misses, or holes in the 2200 - 3200rpm region. Not a lot of power there, but fine for parking lots in 2nd.
I'm sensitive to this because when I had the K&N (and admittedly not jetted for it) this region went to hell. Rode it most the summer like that and just convinced myself a stumble at 2400 -2700 was normal.
Put the OEM back in and learned that 2500rpm is just fine

 

Hey Guys,

Thanks for all the feedback. I've shimmed twice. First time added .030, second time added another .030. I also did a proper TPS mod with real insulated connectors, and I'm right at 500 ohms (side note: my original TPS would only get down to 600 w/out modifying - but I swapped in the TPS from my spare carb, and it can get almost to 400).

I don't feel like TPS did much. The shimming made a noticeable improvement. 2500 RPMs & 3/4 throttle is decent. Full throttle at that speed, or 3/4 throttle below is not horrible - not lugging, but still sounds/feels unpleasant, as in the bike is telling me it would rather I didn't do that.

I think I'm ok with where things are. In 1st and 2nd gear if I actually try to give it full throttle at 2k rpms, it's already at 3k faster than my hand can twist the throttle grip. Before if I did that it would lug and buck like crazy. So I'd say it's acceptable now, and I'm fine with the conclusion that you really don't want to be asking a hawk for a lot of power down this low, but at least it will behave acceptably if I do.

Is it common for people with stock pipes and filter to change the jets? Did Honda really build the bike that far off?

I'm curious about the flo commander, I'll read up on it. It sounds like that is going way to far though. I will never be a 9000 rpm guy like so many of you seem to be. I'm here for the torque, not the hp.

One concern: I could be imagining it, I never thought much about it before - but I feel like during warm-up, on choke, the exhaust is smokey now, where it wasn't before. Also, it seems like the rear cyl is smokier than the front. I wouldn't expect shimming to have any effect on this since the throttle is basically closed. Opinions?

I also wonder if the smoke is related to my other post about gunky looking intake valves.

 

The exhaust is linked, so the smoke at warm up just comes out the shortest way, ie it's not from a specific cylinder even though only one pipe is smoking...

I'm pretty sure it behaved the same way before and you didn't notice, could be a bit more pronounced though, then it's a sign you don't need to use the full choke...

 

The slides are bouncing at idle opening the needle supply for a short period during the intake stroke, dumping some fuel from the main metering circuit, pulling up the needle will definitely affect idle mixture to some extent.

 

After I did the mods.40 shims, 2.25 air mix, and foam filter oiled, TPS @500, the choke definitely acted differently. I could warm it up a bit and go down the road and push the choke back in and it would try to stall before the mods. Now I pull it out to start, within a minute i go down the road through 2 stops and soon as i get moving, push the choke in and that's it. maybe 3-4 minutes tops. I don't know about the smoke, cause I don't let it idle more than a minute with the choke on. Try this: pull the choke all the way out , start it, and push it in and see where it wants to stall and leave it near there.

 

Negative! The slides should NOT be bouncing at idle. They should be resting on the bottom. If they are then there's a problem.

 

What would cause bouncing?

 

Going sooooo fast that gravity gets unstable!

 

I don't see why you want to run below 3000 rpm anyway, except at idle. I downshift as soon as it drops below 3k.

With stock exhaust and air filter/box, I shimmed my needles .020" and had my pilot screws adjusted by a British tech that used to own a SuperHawk (I don't have the tool and he only charged $20).

That solved any minor glitches I had off idle. Still has the very occasional carb fart, but otherwise runs flawlessly from sea level up to 6,000 feet (doesn't like idling at 6,000 feet though).

 

I fired it up only once with the airbox removed, I was surprised to see the slides bouncing, I figured that it would wear out the needles and diaphragms pretty quickly.
It would be nice for someone to fire up the engine airbox open (there's enough fuel in the carb bowls) to have another input.
I can't now I'm fuel injected

 

Really? Well, you've done a lot of mods to your bike. Was this when it was stock? Usually the slides start lifting about 2k rpm, and that's where you'll see and hear them clacking away.

 

Mine did the occasional clackety-clak... Not anything constant at idle, and yeah above 2000 somewhere they started to hop around... Can't say for sure where though... I was kind of busy with one hand holding the fuel bottle the other the throttle and me poking my head everywhere...

I found my rattle though... One of the bolts holding the carb bridge together had worked itself loose... And somehow wedged itself in... The irony is stunning... vibrations works the bolt loose and then it's wedged in so that it sits around rattling for 200+ km of me gunning it through the twisties... I'm pretty sure there are a few laws of physics that say it should be impossible...