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Dynojet kit Vs replacing stock jets

Old 07-12-2010, 10:11 AM
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Dynojet kit Vs replacing stock jets

Hey Everyone,

Can anyone explain to me the difference between just replacing the stock jets, with larger ones after slip ons and K&N filter, vs getting a dynojet kit? Is there a huge difference? Easier to tune? Any info would be great! I have a set of Two Bros hi mount slip on's on order, and a K&N filter.. Wondering if I should get a Dyno kit on order, or will I be able to just get some replacement jets from the local shop.

Thanks!
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Old 07-12-2010, 10:47 AM
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big difference...

A jet kit comes with more than just jets, the big difference being the slide needles are adjustable. Most bikes require much more tuning with the slide needle then with the jets as stock mains for the most part work fine unless you have both exhaust and high flow filter together. Even then you don't always need to replace the mains with larger ones. It just depends on how the bike runs that will determine the need for jets.
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Old 07-12-2010, 11:12 AM
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You will get a few different answers to your question but if it were my bike..... I would not bother with the K&N or a jet kit. Just install the slip ons, shim the stock needles .040" and install a set of #48 pilots, as I have had very good results with that set up.

There are folks here that have had good results with the K&N & Dyno-Jet set up but I could never get mine to run the way I wanted with it.

Also it is usually a good thing to do the TPS adjustment while the carbs are off in either case.
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Old 07-12-2010, 11:33 AM
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FWIW though one persons settings may not work as well for you. The lesson to be learned is to get a base point and go from there. Stock settings are typically a good starting point. I agree with the shimming thing 8541hawk said but have had mixed results with changing slow jets. That just to emphasis that your results may be different.
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Old 07-12-2010, 11:42 AM
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Yea I agree with these guys, it's all about experimenting with your own bike. I have only shimmed my stock needles and have the stock slow/pilot jets, although I have heard of slow/pilot jet swaps I don't really know myself what they do or how to tell if I could use larger ones lol
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Old 07-12-2010, 12:28 PM
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So, pretty much trial by error by the sounds of it! I think I'll see what I can get out of the stock needles, and maybe see what I can accomplish with the jets. I live at about 3500ft above sea level, so usually when we just put a slip on, and k&N with stock jetting, we actually equal out the rich stock jetting for our altitude.

8541Hawk, what kind of TPS adjustments should I be making?
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Old 07-12-2010, 02:21 PM
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Search is your friend but I will help you out this time......

https://www.superhawkforum.com/forum...ead.php?t=9876
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Old 07-12-2010, 02:24 PM
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Haha, yeah I found it after I posted that reply. Was going to come back and tell you not to worry about it.. But thanks anyway! I'm pretty sure that will take care of my speed pulsing, that I posted on another thread.
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Old 07-12-2010, 02:53 PM
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You might find this article of interest, a bit anyway.

http://www.roadracers.co.uk/carbs.htm

If you scroll down to the bottom there's a vtr specific section. Can anyone shed any light on the last few paragraphs?


"If you don't want to buy a jet kit, but do want to improve fuel consumption by up to 3 to 5 miles a gallon, do the following........
Take the needles out of the slides and throw the little shim away. This shim raises the needles in the carbs and will always ensure your VTR runs too rich, hence the high fuel consumption. Trust me, this does work and it makes the bike run a little leaner at the top of the rev range and therefore produces a few more mph."




Is there any truth in this or is it just BS? i'm running a stock exhaust and air filter and could live with 3 - 5 mpg more!
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Old 07-12-2010, 02:59 PM
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IMHO the answer is no.
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Old 07-12-2010, 03:47 PM
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mattijw, in theory it would increase fuel mileage a little by running it a little leaner by lowering the needles. But an engine runs at it's most efficient when the air fuel mixture is perfect, so it would only increase mileage if you were running rich at your altitude. As far as I know manufacturers jet things to run at sea level. So for me, yeah they run rich. So, for me to increase mileage, simply putting a high flow air filter, and a higher flow exhaust, the bike will run leaner or closer to what the manufacturers jetted it to. An engine will not increase in mileage if you run it leaner, because the fuel won't be burnt as efficiently as if it were jetted perfectly.. If that makes sense!
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Old 07-12-2010, 04:12 PM
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Originally Posted by RK1 View Post
In my opinion it is BS. I'm also 99% sure if you set your bike up exactly as that guy recommends (race cans, K&N, his jet, needle and pilot screw advice), you'll wish you hadn't.
+1
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Old 07-12-2010, 04:20 PM
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Yes that makes total sense. I thought it seamed to good to be true. Is the general consensus that the standard jetting is pretty much right? (for a standard bike) I seam to recall when the vtr came out some people were saying it was jetted a touch rich as standard?

Maybe I just need a nice free flowing exhaust...................

Last edited by mattijw; 07-12-2010 at 04:23 PM.
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Old 07-12-2010, 04:36 PM
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Originally Posted by mattijw View Post
Yes that makes total sense. I thought it seamed to good to be true. Is the general consensus that the standard jetting is pretty much right? (for a standard bike) I seam to recall when the vtr came out some people were saying it was jetted a touch rich as standard?

Maybe I just need a nice free flowing exhaust...................
IMHO it's a bit lean on the bottom but fine on the top end with the stock jetting.
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Old 07-16-2010, 09:28 AM
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8541Hawk, So, if I just put a K&N filter in it, and now am getting some major low speed hesitation, would that be my slow speed (Pilot) jets? #45 I think is stock.. Or could it have something to do with the TPs adjust? My idle dropped about 400 rpm, and it fixed the surging I was getting at slower speeds. But now when I pull away from a stop, or even bleep the throttle at low rpm, it completely hesitates, and sounds like it's flooding, or lean.. I tried pulling the choke, which as far as I knew is just a enrichment circuit, and it made no difference..

Also for clarification, there is your main jet, and pilot.. Is there an Idle jet, or is that just another name for pilot, or slow speed jet??
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Old 07-16-2010, 09:43 AM
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Originally Posted by dustinwild View Post
My idle dropped about 400 rpm, and it fixed the surging I was getting at slower speeds. ...

try adjusting your idle back up? lol
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Old 07-16-2010, 09:57 AM
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Pilot/idle/slow jet are all different names for the same thing... You have main jets, pilot jets and a needle to work with...

The reason for you slow/mid speed stumbles are probably the K&N filter... It's completely useless on a VTR unless you build the engine top to bottom with performance parts... There are numerous threads on this forum with people having your exact problems...

A K&N filter does not give you "free/extra hp" like on a lot of cars... Stick a new OEM filter in there and you will save yourself a lot of headache...

Another thing to note... You have had the carbs of the bike, doing the TP mod... Have you balanced your carbs and set the idle back to where it's supposed to be? It makes a very large difference if the carbs are out of sync...

BTW, you are breaking a cardinal rule, making two changes at the same time makes for confused fault finding...

Last edited by Tweety; 07-16-2010 at 10:00 AM.
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Old 07-16-2010, 11:25 AM
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Logged in a little late this morning but Tweety has already covered the answer.
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Old 07-16-2010, 01:54 PM
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Thanks Tweety, I'll toss the stock filter back in, and get the carbs sync'd.. See if that helps. Yes the idle is back up. First thing I did when I fired it back up after mod.
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Old 07-16-2010, 07:38 PM
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One big difference in the Dynojet kit versus using larger stock jets, is the Dynojet kit requires you to drill holes in the slides, so you can't go back to stock.

On the superhawk, the K & N only really can be tuned with our carbs and make more power for a real narrow rpm range. This is fine for the track where you would run 8-10k rpm all the time, but for everyday driving, there is a lot of trial and error tuning to get it running right down low with decent mid and still good up high. Most people who put their superhawk with a K&N on a dyno will notice a flat spot or dip somewhere in the middle rpm range, where airflow in the airbox is disturbed enough to choke power at certain rpms. Sure you will get a few peak hp up top but losing some torque across the mid range will make your bike accelerate slower. My bike dyno acutally dipped from 4-6k rpm with a K&N, but it gave me a peak of 106 hp but bad hiccups around 3500 rpm, which makes the bike had to ride in city traffic.

I gave up trying to make it run decent from 3-4K rpm with a K&N and removed it, although I noticed that adding a fin helped but didn't fix the hiccup, just like putting the needles on the 5th notch. I still need to drop down a size on mains from taking the K&N out but will try the 48 pilots that 8541Hawk suggested with smaller mains. I did notice my mpg dipped when I took out the K&N, and I still have decel popping so it's still not perfect yet.
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Old 07-20-2010, 07:24 PM
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Hi all:

Just joined the forum. So this is my first post here. I have a '98 VTR1000. I put high rise Moriwaki pipes on, the Dynojet kit, and the K&N. Did the work my self (I'm a tinkerer). Took a day of adjusting to get it to run right. Been quite satisfied with the result. It'll backfire and burble a bit when shutting the throttle down from high'ish RPM. Other than that, it's fast and smooth. Ridden from Oregon to British Columbia and back with out any issues.

After about 5 years like this it's getting a bit hard to start. Just needs a good tune up and carb synch. Never dyno'ed it and I don't worry about milage too much.

Guess I'll have to fill in my profile a bit and post a pic or two.
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Old 07-21-2010, 06:38 AM
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Originally Posted by dustinwild View Post
Thanks Tweety, I'll toss the stock filter back in, and get the carbs sync'd.. See if that helps. Yes the idle is back up. First thing I did when I fired it back up after mod.
rot roh! you are about to break a cardinal rule.lol

Seriously, I like to break the cardianl rule because I'm lazy and rather dumb. Now if i'm blazing a trail, that's different, you may need to be a little more scientific. But since this trail has already been well developed relative to specific mods that improve performance by many and diverse others on this forum, some who have verified via dyno, you can get in the ballbark by copycatting their mods. So if you're a lazy, dumb **** like me, you can pick one direction and do everything at once. You might get lucky and get it right and be done the first time, or at worst, have to back in a do a tweak here and there. Now if we had a thread which listed everyones carb mods with their respective performance figures, etc., you'd be all set.
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Old 07-21-2010, 06:42 AM
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welcome aboard 63ronin. The more the merrier.
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Old 07-22-2010, 08:04 AM
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I have a K&N, with Dynojet...tuned by PO, that works well. I've had minimal adjustments to make with 3 different exhausts (Yoshi, Jardine, Mori). That said, if I was changing the jets to a kit, I'd go with FactoryPro parts. They don't require drilling slides, and have more adjustability in the kits I've seen. The Dynojet needles may be more aggressive on some kits (my Hawk GT's for example), but they're a little harder to setup. I've also heard the BMC filter is easier to "tune".
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Old 07-22-2010, 08:10 AM
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Originally Posted by 63ronin View Post
Hi all:

Just joined the forum. So this is my first post here. I have a '98 VTR1000. I put high rise Moriwaki pipes on, the Dynojet kit, and the K&N. Did the work my self (I'm a tinkerer). Took a day of adjusting to get it to run right. Been quite satisfied with the result. It'll backfire and burble a bit when shutting the throttle down from high'ish RPM. Other than that, it's fast and smooth. Ridden from Oregon to British Columbia and back with out any issues.

After about 5 years like this it's getting a bit hard to start. Just needs a good tune up and carb synch. Never dyno'ed it and I don't worry about milage too much.

Guess I'll have to fill in my profile a bit and post a pic or two.
If it's getting hard to start and you've already checked fueling issues, you may have a Throttle Position Sensor that is less than optimally set. Should be set to about 500 ohms. There's how to's in the knowledge base portion explaining how. Welcome aboard!
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Old 02-01-2012, 02:55 PM
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Until my tenant put some kind of tank/carb death in my tank my Hawk screamen from 2000, wheel up at 5000, set down at 8000 and shift. 98 SH KN filter, Erion pipes and as I found out on here (due to the shorter slide springs) a KN jet kit. Occasional burp/fart/die at stop lights when it's over 100 degrees out but stupid smooth underway. Just put the 03 carbs on for the third time, no fuel will flow to the rear cylnder but I'm half way there. When I fire it on just the front cylnder it STILL sounds better that barts Harley next door... sorry bart, just realized I didn't "cap" your first name. Too lazy to backspace and change it. hehehe. Bart IS cool!
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