Home Forums TaG Rotax Max Jet-Tech Max Jettign Software Question

This topic contains 15 replies, has 6 voices, and was last updated by  tony zambos 5 years ago.

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  • #16286

    Ambrose Buldo
    Participant

    I already have a call into Jet-tech support, but figured I’d ask the Newbie question here too.

    Using my weather station and Jet-tech I followed the Jet-Tech Barometer Calibration Instructions at home, no problem.

    Tommorrow, I go to the track.  Before fine tuning,  do I need to re-calibrate either the Barometer of the Jet-Tech as track is 1300′ higher elevation then my home?

  • #16297

    tony zambos
    Participant

    To the best of my knowledge, once you have calibrated your barometer, leave it alone. Make a note on which recording weather station you used and the altitude you used in the calibration setup.  Double check your settings when you replace the batteries in the gauge.

     

    LAD Specialties customer / tony kart / rotax / kt100

  • #16614

    Peter Zambos
    Participant

    Mike, we’ve had nothing but good results with Jet-Tech.  We did not go with their weather station.  Sadly, I can’t remember what we went with and I don’t live with the kart.  Maybe my dad will chime back in.  The thing to remember is that the software is only as good as you calibrate it, so pay attention to the directions. At best, you’ll need three practice session, but, more than likely, you’ll need a good portion of a day’s practice.  Since we’re still old school, and like to check plug color, too, I’d recommend lapping a while per session and coming into the pit fairly hot, so that you know you’re plug color is accurate.  Of course, stop watch, throttle feel and your ears will also help.  With Jet-Tech’s help, very soon we would show up on a morning and say things to each other like, “this feels like a 158 morning.”

  • #16640

    John Savage
    Participant

    To the best of my knowledge, once you have calibrated your barometer, leave it alone. Make a note on which recording weather station you used and the altitude you used in the calibration setup. Double check your settings when you replace the batteries in the gauge.

    On the money, first class advice!

     

    Jetting and Kart Set-up Software

    http://www.rotaxjetting.com

  • #16701

    Ambrose Buldo
    Participant

    What exactly do I look for when inspecting the reeds?

  • #16707

    Brian Degulis
    Participant

    When you tried a new carb did you use your slide cap and spring? I ask because if the spring on the slide is broken or collapsed it may work when you check it without the engine running but when the engine is running and under load the vacum being pulled through the carb can hold it open. Any bind in the cable or anyplace will do the same thing.

    Brian

  • #16715

    Ambrose Buldo
    Participant

    Yes – I used old slide and spring.  Since them, I replaced the throttle cable and put a new spring on it.

    Johns reply on fuel pump pipework got me thinking.  The line from the crankcase to the  fuel pump is much longer then on the other motor.  I will shorten it up as much as possible.  Also I notices this engine uses regular fuel line for the pump plumbing whereas the other motor as much smaller in diameter (and more flexiable) line.  I am going to change over.

     

  • #16724

    Brian Degulis
    Participant

    If it were leaning out it would likely pop and bog when you accelerated through the turn. It really sounds like the slide is not coming down when vacum is present. Is there a spring on the pedal? Any sharp bends in the cable?

    If you cant see anything wrong I would go down the straight working the throttle cable by hand and confirm that the slide is closing.

    Brian

  • #17062

    John Savage
    Participant

    What exactly do I look for when inspecting the reeds?

    Inspect for general condition, no chips etc

    And then hold up to the light and check that the reeds are seated with no gaps (however small) around the cage.

     

    Jetting and Kart Set-up Software

    http://www.rotaxjetting.com

  • #17083

    Ambrose Buldo
    Participant

    John – I pulled the read cage, they are fine.  Only think I can think of now is either exhaust of fuel supply plumbing.

    I will check exhaust pipe and packing when I prep for next season.  Also I noticed on the other Rotax it uses very small diameter line for the pulse line. My line is probably a little longer then it needs to be. I can probably make it 2 or 3″ shorter but will still be longer then on other kart as my pump is mounted under the carb and on other Kart is it mounted sideways to the engine with a ProSpeed Kit.

    Anyone know where I can get the small diameter line to use for pulse?  I was using regular fuel line and maybe I was not getting a good seal on the engine side of pulse line.

     

  • #17113

    tony zambos
    Participant

    Any kart shop or retailer should have pulse line.  Keep it as short as possible without any kinks

    LAD Specialties customer / tony kart / rotax / kt100

  • #16518

    Mike Clark
    Participant

    Ambrose,

    I am curious as to how working with the software went. We are about to buy the software as soon as we receive the Rotaxs. Did you go with the Jet-Tech weather station? We are also going to use a fuel test kit (non Jet-Tech) provided by a team member.

    Thanks,

    Mike

  • #16527

    Ambrose Buldo
    Participant

    Mike – Did not get a chance to use the software this weekend.  Was helping a friend get his new Kart sorted.

    I did get a response from Colin @ Jet-Tech regarding need to re-calibrate and he said it was not necessary as the software accounts for change in altitude.  I only have to re-calibrate the software when I change batteries on the weather station.

    I bought this weather station:  http://www.amazon.com/Ambient-Weather-WS-1171-Temperature-Barometer/dp/B003OSSH9G/ref=lp_397435011_1_2?s=furniture&ie=UTF8&qid=1385402564&sr=1-2  $40. Looks to be the same as the  Jet-Tech, but can’t tell for sure.  I think for our purposes it is more then adequate. The readings on this station match the readings on a Higher End Davis Weather Station.

     

  • #16648

    Ambrose Buldo
    Participant

    While I’ve not used the software at the track yet, I look forward to using it next season.  I fully understand the concept of “Aligninging it” to your carb and engine combo.  We will take the time to do it right.  Impressed with the software so far, and if it works out, would like to get their setup package as well and get rid of my paper notes as I have laptop at track almost always.

    Right now I am still frustrated with the Carb “Over Rev Issue” I discuss a few threads below. I can’t use Jet-Tech until I get it resolved.

    Here is a recap:

    It is a near new newer style Rotax installed on my Intrepid Kart

    Issue: At end  of straight when over 12000 rpm I let off throttle, the revs don’t drop immedatly, in fact revs feels like it continues to climb a bit. I have driven 2 other Rotax Karts on same day, they don’t have this issue.

    I’ve tried main jet from 153 to 165, no help

    I’ve had carb rebuilt and ultrasonicially cleaned no help

    Power valve was rebuilt, no help

    It is not foot, elbow throttle cable interferiance

    Throttle pedal not binding

    Tried new spark plug

    Put good known working carb on and problem persisted

    Installed new throttle, cap, sleeve and rubber gasket under throttle cap

    Made sure carb was pushed in well

    Fuel Pump Rebuilt

    Installed new carb clamps

    Installed new carb to air box socket

    Perplexing is that issue persisted with another carb.    Maybe its the Carb slide or something to do with the reeds?  Any ideas?  At this point gong to have to wait till next season.

  • #16678

    John Savage
    Participant

    It’s not the carb if it was still there with another carb, so as you say check the reeds which is a simple visual inspection and also check the fuel pump and its pipework just in case you are leaning out at the end of the straight.

    If you do decide on setup as well then the best option is to upgrade to Jet-Tech Pro as you then get additional features that you would not get if you used Jet-Tech Max and Jet-Tech Kart Setup.

    Jetting and Kart Set-up Software

    http://www.rotaxjetting.com

  • #16855

    Mike Clark
    Participant

    Yesterday I started going through two DD2’s that were from the world finals. I pulled the carbs and cleaned them. One had a 175 main jet and the other had a 202. One had the slide set to where it was closed at idle (no daylight) and the other showed about .040 to .062″ of an opening. I am assuming both were in as ran setup as they exited track from the final.

    They seem like they were setup vastly different. I have not checked the gearing that is in the karts but based on what I have out of the karts I can assume one is a 36/61 and the other a 37/60.

    I still need to look at some front end settings and brake bias. Rear hubs were off.  One had front hubs all the way in and the other all the way out, but I think they were disturbed. A lot of stuff was off the kart. Rear bumber, radiator, pipe, seats, steering wheels and even some brackets were off.

    Main point is that on a world finals level there seemed to be a big jump between two carb setups.

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