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fitting your own dynojet kit

Discussion in 'Technical and Troubleshooting Torque' started by idontlikemondays, Jul 21, 2007.

  1. so, ive got the braided brake lines in, now its time to fit the dyno jet kit on the firestorm. at first i was just going to pay someone, but after being told it was about 6 hours of labour at flywheels, and they told i could just buy the kit, i thought, well shit, its something im prepared to spend 10 hours on to save 500 bucks.
    so can i ask, how hard is it? im well aware it would be a fiddle, but not rocket surgery? any other special tools needed than a vacuum gauge? any suggestions on a good kit to fit it with? the bike currently has low rise staintunes, and i was going to get a K&N in at the same time.

    any help, suggestions, previous experiances would be greatly appreciated


    (and yes i did a search!!)

  2. most of the dynojet kits are actually for overseas models.
    You can fit it yourself, but a good mechanic will know which parts to leave out and if that applies to your model of bike :)
    Ring around and ask them, if you speak to one who knows that, they're the people to advise you :)
  3. They're very basic to install, the kit usually only consists of larger main jets, and new needle jets.

    You'll need to take the carbs off to swap the main jets.

    A workshop manual would be ideal, but not necessary. Once you have the carbs off (and drained), it's a 10 minute job.
  4. its not the fitting that takes the time, its the carbie tuning after thats the bugger.

    but this is prolly the esiest way without any special tools (apart from a carby screwdriver)

    most often, we are told to adjust the pilot screws “Three turns out†or something similar. Because of the forgiving nature of carburetors, this works pretty well. However, it certainly isn’t optimum and optimum isn’t that difficult to achieve.
    The pilot circuits affect engine operation from idle to about half throttle. The closer you get to half throttle, the less the effect.

    Setting the pilot (idle mixture) circuits.

    You will need the right tools for adjusting the carb pilot circuits. It can be done with a very short ‘flat blade’ screwdriver, but having the correct tool will make the job a lot easier and is well worth the investment (you will burn your hands using a regular screw driver).


    This tool (or something similar) can be purchased from most bike shops or online. It is made by Motion Pro and sold through A1 Accesories in bris

    You will need an ‘assistant’ or helper. They are only going to watch the tach for you during the adjustment. If your assistant has decent vision and can speak, then they possess the fundamental requirements to perform the task.

    the pilot mixture screws are usually capped at the factory and the caps will have to be removed. This is fairly easy, but is best done with the carburetors out of the motorcycle. Simply drill a 1/8 or 3mm hole in the soft aluminum plug and pry it out. You can thread a screw into the hole and pull it out, but this isn’t really necessary. Take care when drilling the plugs. If you break through the plug with the drill under pressure, you will damage the head of the pilot needle.

    Once removed, just throw the plugs away, as they aren’t reusable and you don’t want them in there anyway.

    Re-install the carbs.
    take the bike for a ride to warm it up.
    When you get back home or to your shop, let the bike idle till the fan kicks on. We need to know that it is up to running temperature.

    Shut the engine off.

    One at a time, screw each pilot needle in till it bottoms (gently!). Then unscrew it 1.75 (one and three-quarter) turns. Do this on each carburetor.
    This is a ‘known’ lean setting, but the bike will still start and idle.

    Start the motorcycle and set the idle to approximately 800 rpm.

    With your assistant watching the tachometer, SLOWLY unscrew the pilot screw on #1 carb till the idle starts to climb. Have the other person tell you when the idle starts up. At that point, start counting ¼ turns out. Your assistant is now watching for the tach to DROP a little. Once the rpm starts to drop, just screw the pilot needle back in half way to where it began to rise. You are setting the pilot circuit half way between ‘nearly too lean’ and ‘nearly too rich’.

    Reset the idle back down to 800 rpm and repeat the adjustment on carb #2.
    Repeat this process till you have adjusted all four carburetors.

    Reset the idle speed back to where you normally keep it

    Your pilot circuits are now set to optimum.

    Take the bike for a ride and if you get popping on deceleration, unscrew each pilot needle an additional 1/8 or ¼ turn (just make sure that the additional amount is the same on all four carbs). Stop there. It’s as close as humanly possible to get it.

    You have now set the pilot circuits correctly.

    This should be done at least once a year (temperature and humidity will affect the mixture requirements) and each time you do a valve adjustment.
  5. The pilot screws will still be fine in the standard position with the jet kit fitted, but yes, most carbed bikes would probably benefit from some adjustment over the factory settings.

    Dynojet will probably provide the info as to what they should set be set at to get the most from the jet kit.
  6. Cammo, they are never spot on, i have fitted jet kits to lots of bikes (with aftermarket exhausts and air cleaners) and they always need playing with, the 1.75 turns (as stated in the majority of stage 1/3 jet kits) is just a base level, to get it spot on with a pretty flat fuel air ratio follow the easy steps i outlined and then you KNOW you have it right
  7. i agree with you

    end of the day you should have a pretty good result

    from there you could go and get the dyno done and the final tweaking done , you would have saved yourself an hour or 2's labour by fitting the kit yourself in the first place
  8. guys thanks heaps for the help, especially sluglie!
    well one is for sure, it pays to shop around. i got about 220 bucks and 250 bucks respectively from MCAS and flywheels for the dynojet kit, and got quoted 175 bucks from sydney city lane cove!!!

  9. This post has been handy! I have been looking for one of those remote screwdrivers for about two years, they used to be very common when carbed cars were still around!
    Agree with the idle mix adjustments given above, bike carbs are waaaaay out. I think they get away with it because of multiple carbs....

    Regards, Andrew.
  10. head into repco, there is a brand of tools ABW? its got blue and white on the package, they do all those weird special tools

    they have a right angle screwdriver for solex carbs, got mine a few years ago $35. worked just right for the VFR
  11. Yeah, I used to work at Ripco, they were in the catalogue, but even the staff price was way too stiff! :shock:
    Just ordered one from the US, costing me less than the price I would have got with staff discount! :roll:
    I LOOOOOOOVE buying specialised tools! :grin:

    Regards, Andrew.
  12. I have kit installed on my bandit but my economy was s%#thouse. I took the carbs apart today and set them to the specs from dynojet and now the bike is choking and burning fuel like crazy. I'm scared to run it because it backfires and rumbles. Should I pull the turn the screws right out?
  13. follow the steps i outlined above and you should be right mate
  14. What about the needles? Dynabike set the needles at the bottom groove but dynojet reckon second groove from the top?
    Now all I need's the tool so I can stop burning my hand.
  15. well i fitted the kit into the carbs last night at about 1am! the job was actually quite easy! i was a little scared about drilling holes in the carb slide, but even i managed not to bugger it up!
    just for the info, my mechanic advised me not to install the dynojet vacuum chamber springs, as they are not strong enough, (they only have about 1/4 of the relaxed length of the stock ones!) and will ridiculously over ritchen the mixture on accelaration.
    in the VTR manual it also says not to remove the airbox from the carbs, as it will dethread the holes in the carb (technical term excused!).
    pay this off, if you are carefull you wont strip the threads, and i found it impossible to disconnect the heater hoses and PAIR vacuum hoses with the airbox attached. i hope this saves someone else from wasting an hour trying to disconnect everything with the airbox still installed!

    the more i work on carbied bikes, the more i like the idea of EFI! then again, ive had to replace 6 ECU sensors in my car in the last 18 months!

  16. Good work!

    Howzit ride?
  17. I wouldn't fit a Dynojet kit. Seriously what's the chances it's right for your bike, with your exhaust and the fuel you use in the conditions you ride it?

    If you're not confident with carbies then I'd just take the bike to someone with a dyno, to get it re-jetted.

    Chances are you'll have to do that after you fit the kit anyway, except you'll be and extra $200 odd out of pocket.
  18. cammo, got her running today, shes still running a bit lean since i ran out of time before i had to go to work this arvo, but my hopes are high! i ended up making a pilot srcew adjuster, it actually worked fairly well! ill finish her up on the weekend.

    ibast, yeah fairenough, but for me it was the lesser of two evils, she had staintunes on when i brought her, so i knew i'd have to rejet it. i asked my mechanic what to do, he said HRC jet kit was the best bet, but they stopped making em, dynojet kit was next best option. im not after it to run super perfect or get a massive peformacnce gain, i just want her to run better, and so far its looking good. oh and i got quoted 500bucks for dynowork, plus 250 bucks for a new jet kit anyway.

  19. fricken shit yeah! got her running awesome today, just the slightest hint of popping on engine braking below 2 grand, but im not too worried, its close enough for me. all round power and torque is heaps better, and low down power delivery is smoother and stronger. and power monos are almost too easy!!
    shit yeah!!!!!
    btw thanks to everyone who helped out, especially sluglie, that procedure you gave me worked a treat!

  20. good stuff dom, just make sure its not running rich at all, to save yourself my grief

    nothing better then the sound of twin popping up decelleration anyway :p, oh besides the twin revving at full song drowning out any annoying I4's that are around :LOL: