DynoJet kits?

[White trash]

OK, I know fuck all about carbs, so I'm hoping someone who does can explain this to me.

Why fit a DynoJet kit to your carburetted bike? I mean, jets are jets right? You use different sizes to tune the mixture for better power/efficiancy. Every bike I've ever come accross with a DynoJet kit, unless it's been tuned on a dyno for racing, has run worse than stock. My current bike included.

So, what's the deal? Why have one?

[R6_kid]

I think the dynojet ones are a havea different taper on the needles etc. From what i know a dynojet kit is simply a set that the company came up with after dyno testing the specific bike.

However, there are apparently better alternatives. If you look up my thread about dynojet kits there is a link to a producer that apparently gets better results than the dynojet kits. Also a place in the US (Ivan Powersports?) is also pretty good.

To be honest unless you were going to be gaining 5+hp i dont really think its worth the hassle, my bike came with it pre-installed but when dyno'd at Red Baron it came to a measily 92.6hp instead of teh claimed 102-104hp i should be getting with a dynojet kit, k+n and an open exhaust.

[Sensei]

DON't waste ya money Jimmy they are shit spent $1000s on tunning my GSXR1100 for drags & used Dyna Jet needles etc in it , went good for about 2months till the Soft needles wore out & made the bike run like total Shit & due to their changed shape made bad flat spots through the rev range which was hard to Dyna tune out . Went back to Original needles for the bike & all was Fixed right then . 10.2 sec 1/4 for a 93 GSXR1100 in road trim is bloody quick, only got Mid to high 10's with the Dynajet kit . Spend ya money wisely !

[White trash]

Problem is, it's already fitted. It doesn't run too bad, it's just a bit rich. Makes it a pain in the arse to start when it's hot.

[scumdog]

Do they or any other manufacturer have similar things for Harley that actually work?
And how much hassle are they to fit?

[Sensei]

Problem is, it's already fitted. It doesn't run too bad, it's just a bit rich. Makes it a pain in the arse to start when it's hot.

It want get any better Jimmy the older they get the worse they become due to them been made of soft ally , Try to get some originals .

[Matt Bleck]

Problem is, it's already fitted. It doesn't run too bad, it's just a bit rich. Makes it a pain in the arse to start when it's hot.


Apart from the hot starting problem does it run alright?

Mine does excatly the same thing, I've had the carb's stripped, cleaned n balanced still the same. Won't fire up of the starter if it's hot, but I can crash start it no worries.

I had a search on gixxer.com and it's a pretty common problem with both injected and carbed models. I found this http://www.gixxer.com/forums/showthread.php?t=89276 where the guy replaced the start and reckons it come right.

[Lou Girardin]

The new Dynojet kits use titanium needles. The main advantage is that they have needles, jets, springs etc, all in one box.
Our techs seem to make them work just fine.

[imdying]

Do they or any other manufacturer have similar things for Harley that actually work?
And how much hassle are they to fit?

Read a review recently of a Weber conversion kit for Evos, apparently gave another 10% bhp. Review mentioned that the stock carb can show similar gains if fiddled with, but the Weber was considerably easier to tune up due to interchangeable everything, including venturis. They are supposed to be pretty easy to fit.

A Dynojet kit just eliminates a lot of guess work (i.e. they did that for you), but someone with little experience in tuning can still ham it up. Why have one? Carbs are tuned from the factory to dip in all the right places, the right places being where emissions/noise testing is done. Dynojetting (or manually selecting components if you don't mind the hassle) is done primarily to remove those dips. As you can fine tune for your local environmental changes (temp/humidity etc), you can also gain some power whilst you're at it.

Dynojet were seriously in the shite when carbs were ditched, as that's the core of their business. Fortunately for them they brought some tech that allowed them to intercept ECU signals and adjust them on the fly (the Power Commanders). They're designed for the same task though, removing noise/emission dips in the fueling. By all accounts, the Power Commander 3 is a reasonable piece of kit. The only gripes I hear about them are when they're fitted using the supplied crimp connectors (just asking for trouble, unreliability etc), and people uploading maps to them without actually knowing much about how to tune a bike. If they're soldered into your loom properly, they apparently give little trouble. If they're tuned by someone with some brains, they clean up the torque curve nicely. If tuned by someone with some brains, on a Dynojet dyno (which plugs into the PC3), optimal tuning time is supposed to be pretty damn quick.

[Paul in NZ]

It was a lot easier when there were only 2 or 3 carb makers and a lot of different jets needles availiable. Unfortunately, it's harder to get a range of jets and the trend to multis means even MORE expense (4 of everything)

Enter Dynojet where just having the sticker on your fairing makes you bike 30% faster...

Like everyone else has said - there is no easy path to more power - it takes time and $$ in variable ratios.

[F5 Dave]

Hey Jimmi. A jet kit is only as good as the person who fits it & if it isn’t set up on the dyno then you don’t know whether you need to fit the different options of jets they often supply.

But then they wear. Appears they used to be made very ragged & that makes things worse. Factory http://factorypro.com do jet kits & claim to be much better than dynojet as well as claim to wear better. They also sell new emulsion tubes (that also wear oval even in std bikes with mileage, but worse with dynojet needles).

I was quite happy with the RF after fitting the Factory kit, throttle response was much better, as was economy & a tickle more power, like 2hp, but I changed the worn emulsion tubes so some of this is attributable.

[R1madness]

Problem is, it's already fitted. It doesn't run too bad, it's just a bit rich. Makes it a pain in the arse to start when it's hot.


Its not the dynojet kit causing that. Its your pilot screw setting.
You can get a bike with CV carbs ( i assume you have CVs not flatslides) to idle with the slides/needles/mainjet all removed. Try it. You will be suprised.
or clean your air filter hehehehe.

[R1madness]

Apart from the hot starting problem does it run alright?

Mine does excatly the same thing, I've had the carb's stripped, cleaned n balanced still the same. Won't fire up of the starter if it's hot, but I can crash start it no worries.

I had a search on gixxer.com and it's a pretty common problem with both injected and carbed models. I found this http://www.gixxer.com/forums/showthread.php?t=89276 where the guy replaced the start and reckons it come right.


See my last post. If that fails try to lower the fuel level in the float bowl.

[Gremlin]

They also sell new emulsion tubes...
depends from bike to bike... not all have replaceable emulsion tubes.

I noticed a big difference in my 7 with the factory pro kit fitted... but 2 mechs so far have messed up my fueling, so I'm not totally sure. First mech (without kit) made the bike apparently run lean, causing me issues. Second mech (with kit, he installed) has apparently made it run rich which has caused me problems as well (including a big dip around 3.5-4k revs)... :weep:

Bike is due for another service in 420 ish k, and either they get it right, or I think I will speak to Lou, and see if I can get it checked into AMPS and tuned.

Besides the issues, and flat spot in power, the bike is definitely better for it, and power is pretty damn stomping from 5k revs onwards... especially so considering age and being a 750.

That said... I am soooo over carbs full stop... next year I think an upgrade is on the cards... and its fuel injection alllll the waaaay.

[F5 Dave]

Non replaceable emulsion tubes, what a gyp! 4-5 dip is likley worn needle emulsion tube. Look in with a decent torch with the slides removed. Pretty hard to see but small ovality is a problem. Maybe a precision drill & an insert may cure.

To make it worse the plastic slide guides that push into the carb body wear so the slide rattles more & the emulsion tubes wear out faster. I know this as I have one on my desk now, but was noted on the factory website. Do you think you can buy these guides? Nope. Epoxy please.

[Gremlin]

mine are replaceable... if I send them the whole unit (that would be in the US of course)... ie rebuild... errr.... riiight... can I still ride it to work and back every day while you do that work?

Last mech said that they are a little worn, but not much (and no action is apparently needed)... which ain't bad for a bike about to clock over 70k.

[F5 Dave]

Check the factory site (hard to navigate around but you'll get the hang) & read up about it. Not much wear is required to make the bike fuel badly. Pictures show what I mean.

Emulsion tubes are real easy to replace yourself.

Ahh, I see, yours aren't replacable except by them. understand now.

[White trash]

Well, at the end of it all, the thing DOESN'T have a Dynojet kit as originally explained to me. All is good, bike is tuned, serviced, ready for Trackday IV.

Thanks for all the good advice and things to watch for though guys.

[weberspx]

The Weber carb conversion for Harleys is available from Weber Specialties in Auckland.Ph 09 4435638.Murray Johnson is the man to talk to.The kit fits all Carbed EVOs and Twin cams.Gave 12% more yorque and 7 % more BHP in proper dyno tests.Real easy to fit and set up.

[peasea]

Do they or any other manufacturer have similar things for Harley that actually work?
And how much hassle are they to fit?

I got a kit from JP Cycles which had a range of jets etc and a new spring for the diaphragm, it owed me about 120nz on the doorstep, no hassle to fit (comes with instructions etc) and I wouldn't say it's instant power but there's an edge you can feel. It starts fine hot or cold and pulls well at any rpm.

Check the post from wbrspx re the carb conversion. I trialled one on my Evo and netted 10% on the dyno from a simple carb swap. The joy of these things is that if you upgrade the engine's innards later you can switch venturis and they are also infinitely jettable. The midrange was sparkling.