What Did You Do With Your Nighthawk Today?

[Pete in PA]

65F Today! Done with bike!

Fully stock bike. Washer under needle,  115 main (1 size richer), 35 pilot (stock) Started at 3 turns out on pilot screws too rich. Haven't found a way to adjust them with carbs installed.

Pulled carbs again, 2 turns out. Almost perfect. If you let it sit idling for over a minute it will hesitate slghtly once when throttle is turned.

Probably 1.5  turns is perfect.

Pulls great from 3k rpm then harder and harder till rev limiter. I like!

Front forks are stiffer, I think I can live with it now as is.

EBC HH pads on front big improvement along with new fluid.

Ready for spring!!

[mollusc]

Stock for the 1992 CB750 is 2 5/8 turns out from lightly seated and the main is 110, so you're probably a bit richer with the 115s and the washer.  (See jetting info at https://nighthawkforums.com/index.php?topic=40.msg173#msg173)

I adjust with a stubby screwdriver or right-angled screwdriver and a pair of gloves.

[Pete in PA]

Stock for the 1992 CB750 is 2 5/8 turns out from lightly seated and the main is 110, so you're probably a bit richer with the 115s and the washer.  (See jetting info at https://nighthawkforums.com/index.php?topic=40.msg173#msg173)

I adjust with a stubby screwdriver or right-angled screwdriver and a pair of gloves.

On the 650 and Nighthawk S there is more clearance under the carbs than on the 91-03 750.

49 state 91-03 750  has 112 stock main.

Actually you're supposed to do the idle drop procedure in the USA on the Nighthawk. 

I don't understand why in Canada they can get a spec.  for turns out.

[Bob H]

Started at 3 turns out on pilot screws too rich. Haven't found a way to adjust them with carbs installed.

There may be a knock off, this is the Motion Pro tool

https://www.revzilla.com/motorcycle/motion-pro-90-degree-hex-driver-carb-tool?gclid=Cj0KCQiAorKfBhC0ARIsAHDzslv3AcTZqK5I_6Igzg1z95YgK6CUNsBUDapIkI9q7vKner9GGYwwmIcaAsFXEALw_wcB&sku_id=811334
I haven't used it, but pulling the carbs in and out of those rubber boots would make me buy it.

Have you had a chance to do the sync thing?  I got a Morgan Carbtune.

[Larry Fine]

Haven't found a way to adjust them with carbs installed.

https://www.amazon.com/Motion-Pro-08-0119-Pilot-Adjusting/dp/B000UKD6YC/ref=asc_df_B000UKD6YC/?tag=hyprod-20&linkCode=df0&hvadid=309798558622&hvpos=&hvnetw=g&hvrand=692393926395301008&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9008464&hvtargid=pla-494903209398&psc=1

EBC HH pads on front big improvement along with new fluid.

Give the new pads time to wear into the disc.

[Bob H]

Actually you're supposed to do the idle drop procedure in the USA on the Nighthawk. 
...I don't understand why in Canada they can get a spec.  for turns out.

Are you using a manual? The Idle Drop procedure on Clymer says to "turn each pilot screw clockwise until it lightly seats, then back it out the number of turns listed (2 5/8)
Warm the engine up
Connect a Tach
Start engine,  adjust idle speed (1,000) with throttle stop screw
Turn the No. 2 pilot screw clockwise until engine drops 50 rpm
Turn counter clockwise 1/2 turn
Reset idle speed
Perform these steps for No. 1, 3, and 4 carbs

[Pete in PA]

Started at 3 turns out on pilot screws too rich. Haven't found a way to adjust them with carbs installed.

There may be a knock off, this is the Motion Pro tool

https://www.revzilla.com/motorcycle/motion-pro-90-degree-hex-driver-carb-tool?gclid=Cj0KCQiAorKfBhC0ARIsAHDzslv3AcTZqK5I_6Igzg1z95YgK6CUNsBUDapIkI9q7vKner9GGYwwmIcaAsFXEALw_wcB&sku_id=811334
I haven't used it, but pulling the carbs in and out of those rubber boots would make me buy it.

Have you had a chance to do the sync thing?  I got a Morgan Carbtune.

Oh yeah, sync is done.  I have a Carb Styx II.  Old School, the one with that cool mercury.

[Pete in PA]

Actually you're supposed to do the idle drop procedure in the USA on the Nighthawk. 
...I don't understand why in Canada they can get a spec.  for turns out.

Are you using a manual? The Idle Drop procedure on Clymer says to "turn each pilot screw clockwise until it lightly seats, then back it out the number of turns listed (2 5/8)
Warm the engine up
Connect a Tach
Start engine,  adjust idle speed (1,000) with throttle stop screw
Turn the No. 2 pilot screw clockwise until engine drops 50 rpm
Turn counter clockwise 1/2 turn
Reset idle speed
Perform these steps for No. 1, 3, and 4 carbs

Yep, have a manual.  Have a gear drive right angle screwdriver.

On the last removal I replaced the tamper proof pilot screws with regular ones. Might give me the clearance to do it.

[Bob H]

Sounds good.

Pulls great from 3k rpm then harder and harder till rev limiter. I like!

Was that in gears 1-3, or does it pull well in the higher gears as well?

My 750 behaves well in lower gears, but gutless in 4th and 5th unless you wound it out in the lower gears and are at 6,000 or more in the higher gear.
I likely should do the carb mods that you did (the washers were done years ago to raise the needle a bit).

[Larry Fine]

My 750 behaves well in lower gears, but gutless in 4th and 5th unless you wound it out in the lower gears and are at 6,000 or more in the higher gear.

Sounds like clogged pilot jets to me: no power unless you can finagle the engine to higher RPMs.

[Bob H]

Sounds like clogged pilot jets to me: no power unless you can finagle the engine to higher RPMs.

I would agree if it behaved that way in lower gears - but it doesn't.
My bike hauls ass in 2nd, and 3rd to some extent.
I had the carbs out 10 years ago and I rebuilt them, it actually runs great as long as you aren't trying to accelerate in a tall gear when not on the power band.
Here is an article from 1996 about that years Nighthawk, and their description of a brand new bike is what mine is doing

But the emission control, stock exhaust and intake is part of the picture.
They compare the Nighthawk (as being slow) to the VFR. I had an 86 VFR that was super fast, almost like some of my old liter bikes. I'm just thinking that slightly larger jets may help - curious if Pete has good acceleration in the taller gears.

[Pete in PA]

Sounds good.

Pulls great from 3k rpm then harder and harder till rev limiter. I like!

Was that in gears 1-3, or does it pull well in the higher gears as well?

My 750 behaves well in lower gears, but gutless in 4th and 5th unless you wound it out in the lower gears and are at 6,000 or more in the higher gear.
I likely should do the carb mods that you did (the washers were done years ago to raise the needle a bit).

I was only out the one afternoon so far but it pulls in all gears. Had it a little past 100 mph so that was in 4th I'm sure.

I'd also recommend carb removal, clean, and re-jet. Especially if you have a Cali. bike because the main in it is a 110.

I also run E0 gas. More power, much less chance of gummed up jets.

[mollusc]

I have one of those, and even on the 700S there isn't enough room to use it.  The rise is just too high.

[Bob H]

Yeah, the gear driven 90 degree one looks like it will fit in tighter space.

... clean, and re-jet. Especially if you have a Cali. bike because the main in it is a 110.

Yeah, it is Cali and I have just been reluctant to take the time - but one thing I did do was look at my air filter.
8 Years ago my air filter was oil-soaked from the crankcase breather hose that dumps into the air box. So I put in a new filter. A couple weeks ago I was noticing how gutless my 750 was in 4th and 5th gear, pulled the air filter and it was oil soaked and had spots that were THICK with dirt stuck to the oil. So I put in a new air filter, and detached the breather hose, wrapped the end with a piece of cotton towel and plugged the hole in the air box.

I also realized that as a rider I was "short shifting" and not really getting up to the power band. So with the properly breathing air filter, and taking the RPM up to the max torque range of 7,500 in 3rd, then 4th, the bike no longer seemed as guttless. So half of it was my fault for shifting between 5,000 to 6,000 like just normal riding in traffic.
We both have stock pipes, so they DO NOT sound as mean and snarfy as this video, but it is a great example of that model 750 being run up to the RPM where it's max Torque and HP live. In the comments someone asked if he changed jets and he didn't know what the prior owner may have done.

(his lack of wearing gloves is cringe-worthy)

[mollusc]

On the subject of oil-soaked air filters, I struggled with an issue with my 700S for a year or more, believing that the filters I was using needed to be oiled.  The bike would top out around 7k rpm, and I noticed that the engine would even change how it was running depending on how I positioned my legs while I was riding!
Once I discovered my error and replaced with a clean filter, the rev issues were resolved.  Any effect of leg position became impossible to detect.
I therefore strongly encourage people to check the air filter frequently, especially if your engine has some miles on it and you might be getting oil blow-by that could clog your filter.  These carbs can be incredibly sensitive to incoming airflow.