Ok well thats interesting, been fallowing this thread and have my own started cause of low end leaness. Took the carbs off today and as it turns out I dont have a jet kit, I do have sloted needles. The rear jets are 175/45 stock right? The fronts are 172/45, stock right? The front is stamped 38 but someone scribed 45 in it. Hmmm, I have a stock 45 ordered from local honda dealer.Cleaning everything now then on to the pilot screws.

 

Careful.. if you have a Dynojet Kit their numbers are different from Honda ones.. So a Dynojet 175 is different than a Honda / Factory Pro 175.

 

The rear was a 175 with a star stamped next to the number, the front is a 172 with "fatory" stamped next to it. For some reason someone tuned this thing for High Altitude. Im bout 25ft above sea level.

 

My finished carb set up.

I run Arrow full exhaust with custom baffles, Hiflo paper filter with Burnie Morgan mod, FactoryPro titanium needles, two standard long stacks.

48 pilots, 180 + 182 main jets, rear needle shim in the middle, front needle one slot up, plugged one slide hole in front.

It run just great everywhere, no backfiring, fuel consumption comparable to complete stock bike.
So I can say that Hawk´s basic setup - plugged one hole and rear needle raised by 0.5 mm - is working perfectly and is good way to go. Not sure with 48 pilots and stock cans.
It will be different story with dynojet kit, where are different springs and drilling more holes. Race filter like BMC, KN, DNA will make difference as well, I don´t recommend them with standard carbs, properly setted Dynojet kit could work (what I´ve seen), FactoryPro and stock not.

So thanks for info :-)

 

I just want to thank everyone that has taken the time to share there setup's

I have used this forum as a guideline as I set up my superhawk.

After a week of pulling the required items off to make changes, I have come to a setup that is about 99.9% on the money!!

I have a 98 frame with 2002 motor, a mismash of 02 and 98 parts.

I have set the carbs up as follows

.50 primarys
.180 front main
.182 rear main
Stock needles both .030 shim back.
TPS mod and pair system GONE
Stock paper filter
Both velocity stacks are short,

Bike has carbon two brothers exhaust

Street fighter with ducati monster bars and Risers made in my shop.

The bike runs perfect, no popping on decel, no flat spot, smooth off idle with no backfire or pop through carbs. No carbs farts!

And with the streetfighter style its fast into the turns and easy to ride.

Thanks again to all,

Lol, so here I am a day later... Stuck in a bank parkinglot with my front cyl not firing. She ran so good... And all was spot on, balanced the carbs, argh... I can only assume I was a bit too rich on the front and it finally fouled the front plug. Will find out once I get the plug out.

Here is my ride... Wohoo

 

Try going back to the stock #45 idle jets and go about 2.25 turns out on the mixture screws. That should give you a good idle and won't be rich enough to foul plugs.

By chance, did you lose the front cylinder right after you got gas? If so, it's because you overfilled the tank and gas went into the vent line. That usually causes the front carb to vacuum lock.

 

Hi guys.

I'm from the UK and this is my first post, but I've been reading this thread and stalking the forums for a few days now. I was linked to it from the UK Firestorm site (vtr100.org). This thread is a great read and is really helping me get to grips with my carbs so keep the info coming.

So on to my question, and, as per the title, will this guide work for a UK spec. machine (1999 version)? I ask this now, but in my haste to improve the fueling, I've actually already started the mods. From what my Haynes manual tells me (and from what I've discovered by dismantling the carbs), the UK spec carbs have different needles, and already have 48 pilot jets (although I bought new ones before starting ). A previous owner had switched the front and rear needles, so it was worthwhile taking a look anyway. How would this have affected fueling? I've blocked a hole on the front slide and have put everything back together, although I now need new gaskets for the float bowls which probably aren't cheap (alternatives anyone?) Also, should I follow the recommendations for pilot screw settings? Before I changed them to the settings in the guide, they were both set at 1.25 turns out (factory settings are I believe, 1 turn out front, 1.25 turns out rear). I am very new to working on carbs, but the differences between UK and US specs made me wonder. Also, when I was dismantling the carbs, I noticed that one slide closed faster than the other (upon re-assembly, they both close smoothly and at the same rate). What effect would this have had?

The performance of my bike before I started the mods was as follows: Easy to start, but sometimes cut out (then started up again!) and coughed at low revs. Slightly rough cruising at around 30mph in 2nd/3rd. Extreme backfiring when decelerating (it sounds like multiple cannons being fired); I have aftermarket cans on and the backfiring is worse with the baffles out. Apart from that, the bike is stock (as far as I know) and I do not know when the carbs were last balanced (though I will do this when I next fire it up).

I can't see how following this guide will hurt the performance as it isn't great anyway, but if you think I should do anything differently, please let me know.

Regards, Ben.

 

Hi Ben, my bike is italian and advices from here work, altough US bikes have different setup (don´t know exactly how)

You need to spec your current setup - airfilter, exhausts, main jet numbers, needle positions, to see where can be an improvement.

Imo best way how to setup pilot jets is Idle Drop Procedure described in manual.

 

Wow my first "stickied" thread......

Sorry I haven't been around but I'll try to answer the questions that have been asked. If I miss one, just let me know.

Cheers,
Mike

 

As far as I know the set up should work on your bike with no issues.
Just remember it is a "base line" and each bike will require a bit of fine tuning to get it completely dialed in.

Also the main problem you were having was due to the slides closing at different rates. What had happened is that a diaphragm was not seated correctly. You should hear the air moving in the chamber when you push the slides up and let them close. If the slide just falls closed, then it is not seated correctly. With a lift hole plugged, the front slide will close a little slower than the rear but that is normal with this set up.

The settings I list for the pilots are also a base line, for safety I did state a fairly rich starting point, which IMHO is always better than too lean.

You can and should play around with them to see where your bike runs the best but as started in the last post, the idle drop method is the best way to set them.

 

That's why I HATED installing dynojet kits when I was a tech. I'd always recomend against it. If you ever have to rejet and you don't have a bunch of dynojet specific jets you have to figure out what the conversion is and try to start from there.

Also when filling the holes I'd recomend putting the tape on the outside of the slide then try to fill the hole from the inside. That way the small "head" of epoxy above the hole will further prevent it from ever falling into the intake and going through the engine in the event it should ever come dislodged.

 

The reason I don't recommend sealing the life hole from the inside is that
1) it is very easy to get the epoxy in places it shouldn't be when trying to reach down into the side.

2) there is very little clearance between the Valve Plate (the plastic bit that holds the needle in) which can cause one of two issues. The possibility of not being able the fully seat the Valve Plate and also the possibility of causing a unwanted change in the air flow through the slide.

As for the plug falling out, if it ever did happen the chances are slim to none that any damage or problems would occur due to the temperature of the intake valve, which would melt the small plug almost instantly IMHO

 

Agreed. It probably wouldn't hurt anything but in the event the timing was just right so it got caught in the valve seat when the valve closed or something it could cause an issue. And that's only in the slim chance it actually fell out.

I'm not really following you on it affecting the air flow in the slide being the air flow is on the outer side of the slide where you would be placing the tape so that it was perfectly smooth with the slide surface, obviously removing the tape once dried.

 

On the off chance that the plug came out with the engine off, maybe.
Though IMHO there is a greater chance of it coming out while the engine is running and even at idle the valves are opening and closing so fast I just can't see it happening. Though like always YMMV

What I'm talking about is how the slide lifts. Air is pulled out of the lift hole which then causes a pressure differential between the inside of the slide and the carb throat, which causes the side to be push up.

If one got a little too liberal with the epoxy you could end up with some weird flow paths which might change the speed at which the slide opens and closes.