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Jetting and Mileage Success!

Old 04-28-2008, 02:44 PM
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Jetting and Mileage Success!

Just wanted to post regarding my recent jetting experience to add to the general knowledge base here.

My bike is an '03 with Jardine high mounts. The bike ran pretty good overall, but did have a lean 3k surge that would (mostly) clear up after the bike was fully warmed. It's something I could have lived with, and I figured I was getting decent gas mileage because it was borderline lean @ 3k. I kind of resisted jetting because I was concerned that my mileage would go to hell.

A couple of weeks ago, one of the members here posted that the Factory Pro +4 ignition advancers were available again, so I thought, why not, 60 bucks to help the 'Hawk run a little better. So while I'm on their site I see the jet kits and I decide to get one (maybe lose a few mpg) and the advancer (maybe gain a few back).

My first attempt at jetting was a bit of an experiment that wasn't quite right, and I made a few rookie mistakes in the process, but the second attempt was a success. (If at first you don't succeed, read the directions)!

So all of this to say that I went with the Factory Pro suggested settings of: 175f / 178r, needles in the 3rd (middle) position, #50 pilot jets, fuel screws 2.5 turns.

I am very pleased with the results. The bottom end is now very strong and responsive with good power through the rev range. Did a few runs to check gas mileage and got 47 mpg cruising at a steady 4k/70 mph, and 32 mpg with a mix of very aggressive 2nd and 3rd gear twisties blowing a little packing out of the Jardines and 80-85 mph freeway back home. All in all a good day!

Last edited by jbaxx; 04-29-2008 at 05:15 PM. Reason: grammar
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Old 04-28-2008, 03:08 PM
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Originally Posted by jbaxx View Post
Just wanted to post regarding my recent jetting experience to add to the general knowledge base here.

My bike is an '03 with Jardine high mounts. The bike ran pretty good overall, but did have a lean 3k surge that would (mostly) clear up after the bike was fully warmed. It's something I could have lived with, and I figured I was getting decent gas mileage because it was borderline lean @ 3k. I kind of resisted jetting because I was concerned that my mileage would go to hell.

A couple of weeks ago, one of the members here posted that the Factory Pro +4 ignition advancers were available again, so I thought, why not, 60 bucks to help the 'Hawk run a little better. So while I'm on their site I see the jet kits and I decide to get one (maybe lose a few mpg) and the advancer (maybe gain a few back).

My first attempt was a bit of an experiment that wasn't quite right, and I made a few rookie mistakes in the process, but the second attempt was a success. (If at first you don't succeed, read the directions)!

So all of this to say that I went with the Factory Pro suggested settings of: 175f / 178r, needles in the 3rd (middle) position, #50 pilot jets, fuel screws 2.5 turns.

I am very pleased with the results. The bottom end is now very strong and responsive with good power through the rev range. Did a few runs to check gas mileage and got 47 mpg cruising at a steady 4k/70 mph, and 32 mpg with a mix of very aggressive 2nd and 3rd gear twisties blowing a little packing out of the Jardines and 80-85 mph freeway back home. All in all a good day!
Is not 175/178 the stock jetting? I'm not sure the 50 pilot is needed, at most the hard to find 48. Without the pilot jet, you could have achieved the same result just shimming the OE needles about .040". Not sure the +4 advancer is the ticket to much improved mileage. A slow right wrist does do the trick as you stated.

Greg, what is your opinion again on the advancer?

Last edited by skokievtr; 03-06-2016 at 11:31 AM.
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Old 04-28-2008, 03:08 PM
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Heh, congrats on your success. I went with V&H street baffle S4s and Dynojet 175f/180r which is pretty close to stock and I think the dynojet version of where you're at. I also cranked the tps down form near 900 to 500 ohms. My mpg is same as yours and I got what I was really after- perfect carburetion from idle to redline in every gear. Perfect response to small throttle adjustments at every rpm in every gear. You didn't mention, but have you installed the ignition advance rotor?
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Old 04-28-2008, 03:21 PM
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Yes, the mains are stock, but it didn't run right until I put the #50 pilots in. The advancer is installed, and the tps is 500 ohms.

I am fully aware that others have gone to bigger main jets and used the stock pilots. I got what I was after, which was to fatten up the bottom, improve throttle response and maintain fuel economy.

I don't claim to be a jetting guru, just reporting successful results.
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Old 04-28-2008, 03:30 PM
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How's your idle? If you find it is hunting or loading up after periods of idling you are probably (I'd actually say highly likely) rich at idle. Very few people have been able to run the #50 pilot and be happy with the results. Most of those had full exhaust and a filter. Seeing as you are at sea level, I think you could probably go up another size on the mains, if not just to be on the safe side of stoichiometry. Lean is mean but it's also not as safe. You won't lose much mileage by going up on the mains unless you rape the crap out of the bike at high rpm all the time.

As far as the advancer goes, I personally found a hp or two and better throttle response from the mod. To be honest I never calculate mileage on the bikes. I'm usually having too much fun to take the time!
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Old 04-28-2008, 03:40 PM
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Originally Posted by Hawkrider View Post
I never calculate mileage on the bikes. I'm usually having too much fun to take the time!
There it is. I'm glad my VTR gets good mileage, but if that was what I was really after, i would have gotten a Ninja 250. I bought the VTR 'cause it turns every street/road/highway into my own personal friggin' amusement park.
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Old 04-28-2008, 03:44 PM
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Actually, my first attempt was to go up one size on the mains, leave the pilots stock as some have suggested. I noticed some high rpm improvement as you might expect, but it was really lean from about 2k to around 4k.

I ended up just following the suggested settings and it runs great. Maybe not perfect, but pretty darn close and I still need to recheck my sync. As far as idle mixture it was slightly lean (hunting) at the 2 turns I found it at, but seems pretty stable and happy after adding another 1/2 turn.
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Old 04-28-2008, 03:51 PM
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I never really worry about mileage too much either, just wanted to have some kind of baseline comparison. At least I know I can get good mileage if I want (or need) to.
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Old 04-28-2008, 03:53 PM
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Wow! Really? #50 pilots AND 2-1/2 turns? You must have one hungry VTR! Well, see how things go after a couple hundred miles, and I recommend you pull the plugs for inspection after a 5 minute idling period just to be sure. Good job though! For most of us it usually takes 3-4 times of trial and error before we find the sweet spot.
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Old 04-28-2008, 04:04 PM
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Haven't checked the plugs yet, just did a few "shakedown" road tests. What would be your suggestion if I find I'm rich at idle. The stock pilots didn't work. Turn the mixture screws back?
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Old 04-28-2008, 05:04 PM
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As I have explained before in other jetting threads, the pilot jet is like a "coarse tune" **** of an old FM radio and the mixture screws are like the "fine tune" ****. The fine tune **** has a limited range of adjustability. If you're too far off on the coarse **** you will never be able to tune into the station. You have to move the fine **** back to the middle and readjust the coarse ****. So, in jetting terms, if you are still rich after adjusting the mixture screws into, say, 1/2 turn out then you need to go to a smaller pilot jet because you're flowing too much fuel with the pilots to allow fine tuning with the mixture screws.

So if your #45 pilots didn't work because they're too lean and the #50s don't work because they're too rich then the #48's are the answer.
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Old 04-28-2008, 05:17 PM
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Cool, thanks!
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Old 04-28-2008, 06:37 PM
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well, since we are on the subject. I just removed my custom uni filter, installed a k&n. Runs like chit. Give it gas, cuts out spits amd sputters.
Need more fuel?
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Old 04-28-2008, 07:16 PM
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More than likely. Try choking it a little and see if it improves.
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Old 04-29-2008, 03:25 PM
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Brought the bike into the shop today, sync'd the carbs and let it idle for 5 min as Greg suggested. Pulled the plugs, and even I was a little surprised that they were a perfect tan color. I don't think I could ask for better.

So, let the record reflect: the #50 pilots DO work with the stock main jet size.

No disrespect intended to those who have achieved different results with different setups. As I stated earlier, I not a jetting guru, just reporting successful results. I did not come up with these settings on my own, just followed the Factory Pro recommendation.

Hopefully this thread will help someone else that is jetting or thinking about jetting their bike.

Last edited by jbaxx; 04-29-2008 at 05:20 PM. Reason: spelling
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Old 04-29-2008, 03:46 PM
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thats awesome that it worked out for you. i just wish i had the time and money to do few mods to my hawk.
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Old 04-30-2008, 08:56 AM
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Good stuff, Greg.

I never had an idle issue. I went to #48 pilots to stop lean decel popping.
I used an angled idle adjuster tool to fine tune the mixture. I thinke there is too much variability to say "2-1/2 turns out" is the best setting.

Also, I ended up running lean on the top end because I live at high altitude. Most of my riding was between 4500 and 8000 ft, with a 7300 foot pass on the way to and from work. I went down a size on the mains to cut down on the black soot in the tailpipe. If I went up a size on the mains and dropped the needles one notch I ended up with the 3k stutter.

In retrospect, it's better to run it fat, because I got into trouble at sea level. All part of the learning experience.

Last edited by RCVTR; 04-30-2008 at 09:02 AM.
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Old 06-13-2008, 06:58 AM
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I have a Innovate w/b and have had my bike jetted correctly for about 6 months now. The wideband doesnt lie. It idles to rich with 48s even with screws right in. If I lower the needles it leans the idle a little but then it will surge at 3000rpm. So I had to go back to 45s and run the DJ needles on clip 6. much better. BTW i jetted top end first and used big mains to find the point at which they come on then went down in size until I got reasonable afrs. They are at 12.4:1 still to rich for a low comp twin cam. And I have 172 mains front and rear. I need to drop to 168 or maybe 165 to get the afrs closer to 13:1. That was the easy part, experimenting with 48 pilots with the DJ needles was next. I ran on the 4th clip but then I had a lean hole. Going richer on the needle fixed the lean hole but then idled rich. 45s fixed the problem. I have not used factory pro needles but they may require richer pilot jets due to there design. Although 48s is more sensible approach. The bike pulls hard from idle to redline and power is smooth, just needs to be leaner.

note with 180-185 mains my WOT afrs were 11:1!
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Old 06-13-2008, 02:08 PM
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hymey,are you using DJ or Keihin mains and how many turns on the mixture screws did you end up at.I've been running 45's,2.5 turns,5th slot on DJ needles, 182 Keihin mains f/r and seems to run perfect with either stock or BMC filter.I haven't felt the need to touch the carbs for three years,but it's going to be raining for the next 2 days and of course always looking for an improvement.
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Old 06-13-2008, 03:47 PM
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This thread may be new to some but this topic has been covered many times. Jetting to an ďidealĒAFR is only one part of the equation. Hypothetically it may be possible to carburate close to say 14.7:1 but not at all engine speeds and loads and at all temperatures and humidity levels (given stock gears or even at my preferred 16f & 43r), at least not with our relatively huge and basic carbs on our wonderful twin. Tuning on a dyno with all the tools still may leave you rich here and lean there. If you are tuning for the track, it is actually easier but on the street, the parameters are too large for perfect jetting. We can tune for good mileage (lean and flirting with damage), low, mid and top end power. Given the OE filter (which I prefer) versus a K&N type hi-flow (and less filtering), the TPS set for about 500 Ohms and PAIR system properly removed, no major engine mods except for some slip-on cans (a full system does not buy much), balancing the pilot size (45 or at most 48) against the fuel screw (2.5 turns out is a good standard), the jet needle height (so many notches from the top, or in my case shimming the OE needles .045Ē), the needle jets (OE in most cases), and the main jets (Iíve found that 178/180 is all you need given OE is just one size down from that and any less should be lean), you still will be making compromises. In the end if your mileage sucks and the plugs are black and sooty, you are running rich. If the engine surges and the plugs are whitish, you are lean. Obtaining a nice tan color plug insulator is gone with the fuel we use, so now its more a grey color, is all dependent on the type of riding/traffic you do. The are other signs of rich and lean but I donít feel like getting into the minutia. Bottom line, if your happy, Iím happy.
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Old 06-13-2008, 06:17 PM
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Originally Posted by jbaxx View Post
Haven't checked the plugs yet, just did a few "shakedown" road tests. What would be your suggestion if I find I'm rich at idle. The stock pilots didn't work. Turn the mixture screws back?
Don't idle much!

I turned my idle down to book specs because it was too high (about 1500) and the bike ran like ****. Lumpy, loady - just ****. I turned it back up and everything is cool, smooth and it hauls like a dog sled all the way up.

I'm not sure I can get your mileage but I'm very happy with the pull. The PO did the jetting so I really don't know what I've got.
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Old 06-14-2008, 06:03 AM
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I give up reading plugs when leaded fuels were banned. In fact you wont come close. 185 mains feel good and the bike will pull hard but afrs will be about 11:1 at WOT, but then again I am in Australia and our fuel is vastly different to yours hence why I have different jetting.

You are pushing sh%# up hill to get a superhawk to run at 14.7:1 at cruise(without surging). I find the big CV carbs are slow to respond and my bike goes to 14.7:1 for a split second the rest of the time its at 13:1, even on the highway. They idle best about 13.5:1. I get that at 3 turns out with 45s, 48s about 1 turn.

I am still at 12.4:1(6000 to 10000 rpm) which is pig rich with 172 keihin mains. I will be going to 165 mains to try and get 13.0-13.2:1 WOT 3rd gear.

I tune on the road and track, I have my own tuning business tuning LS1 chevs. And I can get max power from street and track tuning and then confirm power on the dyno in which 99% of the time, is as much as it will make. The LS1 V8s like about 12.8:1 with over 10:1 comp running more timing.

The VTR is a low comp twin cam with not a lot of timing, they like about 13.2:1 WOT. 1st and 2nd may get to 13.5:1 but this is still safe, Economy will improve overall as if you get your topend afrs correct the rest will fall into place without to much work. When I put the 165s in I will do a log and see how it looks, Plus I am certain I will require 48 pilots then as the leaner mains have a tendency to lean the mid and bottom to a certain degree.
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Old 06-17-2008, 08:01 PM
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Hymey, at 175/178 I'm told I'm still leaving a black cloud behind me at WOT which supports what you are saying here. Do the keihin jet sizes compare to the factory pro jets? Perhaps I can smaller on the mains still. Think I have a 172 in the kit and could change to 172/175.

Running 48 mains at 1/2 turn open screws and factory pro needles 2nd clip from bottom.
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Old 08-19-2008, 03:12 AM
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You can experiment with it, 175 178 are keihin jets same as factory pro, you could swap them out to 172 175, Just by a 172 main jet and go from there.
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Old 08-19-2008, 04:10 AM
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heyy, hymey's back!
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Old 08-20-2008, 02:45 AM
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sorry for the slow responses. I am having jetting issues myself at the moment, this cold weather is making the bike run lean on the way to work at 6am.

I have a set of 48 pilots to try, it is getting the lean 3000rpm stumble. I tried raising the needle 1 clip but it got rich in the middle and made the transition of pilot to needle jet more noticeable.

cheers
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Old 08-23-2008, 04:56 AM
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Originally Posted by TheRezyReb View Post
well, since we are on the subject. I just removed my custom uni filter, installed a k&n. Runs like chit. Give it gas, cuts out spits amd sputters.
Need more fuel?
I know this is a bit old now, so hopefuly you got it sorted out.

I have a Unifilter, and it is a lot bigger than the K&N and flows more air. You may need less fuel with the K&N filter installed.
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