Home Forums Rotax Max Need EVO Kit help please.

Tagged: 

This topic contains 19 replies, has 6 voices, and was last updated by  Jon Clem 6 months, 2 weeks ago.

Viewing 20 posts - 1 through 20 (of 20 total)
  • Author
    Posts
  • #61733

    Mike Bruce
    Participant

    I ran with an EVO kit for the first time this weekend. I have read thru all the threads about EVO as far back as 8 months. I see where some things have worked for some and not for others. Here is what I am experiencing:

    The motor gets up to 12,500 – 12,800 RPMs very nicely, then it struggles to get any more RPM’s on the longest straight. It does eventually get up to about 13,100 but it takes probably another 100 yards to squeeze out those last few RPM’s. After reaching around the mid 12,000 RPM range the engine tone changes to a flat sound. Most laps the engine would hesitate midway down the straight for just a blip, then struggle to build RPM’s after that point.

    I have an upgraded harness and kit with the pressure pulse setup. It looks as if there is another upgrade after mine that includes two brackets and yet another harness ?

    I have tie wrapped the wires as recommended, I have put the ground wire where recommended, I have installed everything as recommended. I did not put the little pill in the vacuum line because of something I read in another post. Maybe I should?

    Any help or suggestions will be much appreciated !

    #61762

    Andy Seesemann
    Participant

    Hey Mike,

    Lets go another direction.

    Where are you located and what main jet are you using?

    Andy

    Andy Seesemann
    Orange, CA.
    Full Throttle Karting
    www.fullthrottlekartingshop.com
    Challenge of the Americas
    www.rotaxchallenge.com
    USRMC Director
    andy@gorotax.com
    WKA District 10 Trustee

    #61788

    Rob Kozakowski
    Participant

    I would try to add an additional crank sensor gasket (Rotax part# 431 500<span style=”color: #000000; font-family: ‘Open Sans’, Arial, Helvetica, san-serif;”><span style=”font-size: 13px; line-height: normal;”>)</span></span>

    It was a common “fix” for a lot of people in our area

    #61792

    Mike Bruce
    Participant

    Hey Mike, Lets go another direction. Where are you located and what main jet are you using? Andy

    I was racing at AMP in Dawsonville Ga. I started the day with the 130 factory installed jet in the AM. I have the “Jetting for Rotax Max EVO” app on my phone and it told me to run a 128 jet with the needle on the 3rd position. I stayed with the 130 for the first session because I thought it would be better to be rich than lean. For the second session I switched to the 128 jet with the same feel and results. If it was a jetting issue, was I possibly running the bowl out of fuel with the big jets? Maybe I need to raise the floats a little?

     

    Thanks

    #61793

    Mike Bruce
    Participant

    I would try to add an additional crank sensor gasket (Rotax part# 431 500

    Thanks Rob…. that was probably going to be my next step just because its probably cheap and easy.

    #62540

    Roman Alekseenkov
    Participant

    If crank sensor is picking up too much noise, then without crank sensor gasket the engine won’t rev past 12500. At least, that’s the symptom that I had in Feb 2015. You could hear a bad sound when it cuts off exactly at 12500, and it feels like an electrical issue. If it revs past 12500 and slowly picks up RPM, I doubt it’s that.

    Hard to tell anything else without knowing spark plug type, float height, etc. My guess is that it’s still too rich with 128 and 130. Give it a try with Denso IW-27 and 125 main jet. And make sure you have the right gear ratio and floats are not too lean.

    P.S. It’s not uncommon to have people run 120 and 122 too, so you can try this for 1 session – it’s not going to hurt the engine.

    #62630

    Mike Bruce
    Participant

    Thank you Roman.

    #63056

    Mike Bruce
    Participant

    Update:

    After installing the new wiring harness, bracket, and adding 2 gaskets to the rank sensor, the motor is running much better. I took 3 seconds on of my lap times. Motor turned 14200 RPM was crisp and pulled hard. Thanks for the suggestions. Now I just need more track time.

    #63168

    Russ Kemple
    Participant

    The EVO engine will run 15000 RPM.  I run 115 or 113 main jet.  Once I started using the smaller main jet it was a whole new motor.

    #63173

    Mike Bruce
    Participant

    The EVO engine will run 15000 RPM. I run 115 or 113 main jet. Once I started using the smaller main jet it was a whole new motor.

    Wow, that seems lean !

    #65555

    Jon Clem
    Participant

    I also need help.  Pre-EVO upgrade, no issues.  Ran all season, same jet happy. Fresh rebuild by respected and talented Rotax dealer.

    After upgrade, won’t run past 10,500 or so.  Stumbles down long straights, power out the ass from 6,500 to 9,500.  He was convinced it was jetting.  Jets tried were 130, 132, 127, 125, 122, 118.  Nothing worked, no low end with 118.  Swapped carbs with the good original.  Same thing.  Stumbles at 10-10500.  Tried a buddies brand new ignition, coil pack, removed the pill.  Power valve is definitely opening at 7500.

    Now what?

    I miss my old engine.  I ran two new series with the EVO upgrade…..MASS and Championship Enduro Series.  The straightaway at Gateway sure gives you a long time to think about the “upgrade”.   Everything is grounded, mounted with the new wiring harness upgrade version.

    Everyone that ran Rotax this weekend had the kits still in the box…..

    Thanks,

    Jon

    #65557

    Mike Bruce
    Participant

    I also need help. Pre-EVO upgrade, no issues. Ran all season, same jet happy. Fresh rebuild by respected and talented Rotax dealer. After upgrade, won’t run past 10,500 or so. Stumbles down long straights, power out the ass from 6,500 to 9,500. He was convinced it was jetting. Jets tried were 130, 132, 127, 125, 122, 118. Nothing worked, no low end with 118. Swapped carbs with the good original. Same thing. Stumbles at 10-10500. Tried a buddies brand new ignition, coil pack, removed the pill. Power valve is definitely opening at 7500. Now what? I miss my old engine. I ran two new series with the EVO upgrade…..MASS and Championship Enduro Series. The straightaway at Gateway sure gives you a long time to think about the “upgrade”. Everything is grounded, mounted with the new wiring harness upgrade version. Everyone that ran Rotax this weekend had the kits still in the box….. Thanks, Jon

    Jon, I feel that my problem was solved by putting the gasket on the crank sensor. That’s when mine improved the most. I have a question for you …. what difference did you feel with and without the pill in the line?

    #65558

    Jon Clem
    Participant

    It actually wouldn’t reach the same RPMs.  Started stumbling at 9,000 or so.  I forgot to mention that I also went up to a jet of 140 during the race.  Lower power, lower RPMs.  I am SURE it was really rich.  My buddy has the same setup, and he was running a 125 or so……

    Nobody near me has had any issues.  Guys at the track said gearing or jetting.  I keep preaching to them that I don’t think it is carb/gearing related since the carb swap has the same exact symptom.

    I will as also told that the vacuum lines layout, and length are critical.  I haven’t had chance to look at that yet.

    It am assuming that the crank position sensor is the same one as last year…..

     

    #65577

    Mike Bruce
    Participant

    It actually wouldn’t reach the same RPMs. Started stumbling at 9,000 or so. I forgot to mention that I also went up to a jet of 140 during the race. Lower power, lower RPMs. I am SURE it was really rich. My buddy has the same setup, and he was running a 125 or so…… Nobody near me has had any issues. Guys at the track said gearing or jetting. I keep preaching to them that I don’t think it is carb/gearing related since the carb swap has the same exact symptom. I will as also told that the vacuum lines layout, and length are critical. I haven’t had chance to look at that yet. It am assuming that the crank position sensor is the same one as last year…..

    Jon,

    So was it better with or without the pill?

    Install an extra gasket between the sensor and the engine block. That seemed to help mine. Also, I seem to need to run 2-3 more teeth on the axel gear than my friends without the EVO kit to get the same RPMs.

    #65588

    Jon Clem
    Participant

    It actually wouldn’t reach the same RPMs. Started stumbling at 9,000 or so. I forgot to mention that I also went up to a jet of 140 during the race.  I will be suggesting to my engine guy that I drop it off and let him dyno it.  I am getting tired of the issues.

    I will have him put in a second gasket while on site.  I want him to see what is going on before he tries anything.

    Thanks,

    Jon

    #65594

    Roman Alekseenkov
    Participant

    I went through all of this last year.

    INFORMATION BULLETIN: Dellorto Ignition System -How to Assure Faultless Function

    I had an issue that the engine stopped revving past 12500 after the upgrade. Turns out it needed a crank sensor gasket installed, so it doesn’t pick up as much noise from the crank.

    Also, all of a sudden an engine stopped revving past 10000 during one of the races. Wiring harness (EVO v1) went bad.

    I would try a crank sensor first. If you are determined to take an engine to your engine builder, may be get him your wiring harness as well

    #65625

    Mike Bruce
    Participant

    Roman,

    Do you have the pill installed in your pulse line ?

    Thanks

    #65647

    Roman Alekseenkov
    Participant

    We tested with and without metal restrictor in the black hose and it didn’t seem to matter

    #65671

    Jon Clem
    Participant

    I had the same symptom happen with and without the pill.  Thanks for the heads up…….I will get some gaskets on order pronto!

    Jon

    #66314

    Jon Clem
    Participant

    Thanks for all the help here!  I installed the crank position sensor gasket, that was an instant fix!  My engine guy made one because Rotax was out of them…….imagine that!  I put in a 125 jet and that thing had too much power for me. It was a handful!  I love it…..now to get the chassis setup right!

     

    • This reply was modified 6 months, 2 weeks ago by  Jon Clem.
Viewing 20 posts - 1 through 20 (of 20 total)

You must be logged in to reply to this topic.

Karting's News and Information Leader ekartingnews | an HMG publication