EVO Symptoms/Failures/Remedies
Posted: Sat Aug 15, 2015 2:23 pm
Hey all,
I know that a number of us here at the club have suffered, or are suffering from issues with the new EVO Upgrades. I thought I'd post my problem here and I hope others will follow suit to enable any future issues to be diagnosed quicker based on other people's findings so far.
SYMPTOM
After installing my EVO upgrades, the kart ran great with no issues. In the last 2 weeks or so, I've been experiencing a loss of low RPM power exiting the two slow hairpins of turns 11 and 13 (running Clockwise now).
FAILURE
After trying a number of things to improve the situation, I eventually found that my issue was caused by the Power Valve (PV) staying open below 7600rpm. The reason this was happening was due to a broken wire at the connector for the PV Solenoid for me (see pictures). We have also seen the wire from the Ignition Connector to the PV Solenoid be damaged at the Ignition Connector too.
REMEDY
As the problem is part of the new wiring harness, I had to replace the complete harness to fix the problem.
Whilst trying to fix the low RPM power issue, I went through a number of things before finding the problem. When I first noticed the issue I observed the PV on the stand and I could see it opening and closing but couldn't say for sure it was 0% - 100%, so thought maybe it was never closing fully. Carb adjustments made no real difference, changing the exhaust packing, air filter, spark plug, re-building the fuel pump etc etc obviously had no impact either. I was always concerned that it was PV related and my gut feeling was that it wasn't closing fully below 7600rpm and Joey from Overdrive Motorsports mentioned that maybe the slide was sticking in the cylinder. After speaking with Joey, it appears that the earlier cylinders (mine is an '06) have a slightly different casting to the later ones ('09 onwards?? can someone confirm this year?). This means that with the new PV assembly, the body of the PV fouls on the cylinder and 'could' cause the alignment to be out on the slide valve and possibly cause some binding in the cylinder. The bottom of my slide already shows signs of wear on both sides of the underneath, suggesting this may have been happening with mine. I have filed the body of the PV since and also some of the cylinder casting to ensure there is daylight between the two. I believe this was found on a DD2 first of all.
Anyway, whilst I was running my kart on the stand 2 days ago, I observed the PV and noticed that it opened at 7600rpm ok, but was closing way below that at around 5000rpm, before eventually staying open all the time. I suspected the PV Solenoid had failed, so tried a known good one, which seemed to work initially, before doing the same thing. I then tried another Ignition module suspecting it may not be sending the signal to the PV Solenoid, but the same thing happened as with the solenoid. I am running on the 'Pressure' set-up for the PV and the way the solenoid works is as follows:
* At start-up, the PV Solenoid has 0V to it and it is open between the bottom, silver port to the side port which allows the pressure into the PV, thus opening it up slightly
* At 3000rpm after initial start-up, 12V is applied to the PV Solenoid from the Ignition module which switches the Solenoid to allow the pressure built up in the PV to be vented back through the side port from the PV to the open vent port on the top of the Solenoid, thus closing the PV
* During normal operation, the PV is closed below 7600rpm (or 7900rpm if you have both ground wires connected) and the PV Solenoid has 12V 'applied' to it from the ignition module with the Solenoid in the venting position
* When the RPM increases to 7600/7900rpm, 12V is 'removed' from the PV Solenoid and switches to the pressure position allowing the pressure from the Crank to be applied to the PV Bellows, opening the PV up
* As the RPM decreases below 7600/7900rpm, the procedure is reversed and the Ignition module 'applies' 12V to the PV Solenoid again, switching it back to the venting position which removes pressure from the PV Bellows, allowing it to close
Due to the ignition module and solenoid not fixing my problem, the only common part was the harness. When I ran my Kart on the stand again yesterday before changing the harness, I tried manipulating the harness around the plug connector to the PV Solenoid and I could get the PV to work from time to time. After the umpteenth removal of the connector, the wire above broke off, revealing the cause of all my problems. The copper wire inside had obviously broken some time ago, but the outer red insulation was still intact causing me to have intermittent issues as the wire would touch back together sometimes, allowing the PV to work on occasions. So, even though the harness appears to have fixed my low RPM power (track test not done at time of writing), it's nice to know 'exactly' what was causing it within the harness. Obviously, another connector with 2 flying leads would be all that was needed to fix this, but it should be a warranty issue for the harness anyway.
Sorry for the long post, but hopefully we can build up the info' regarding EVO issues here to help everyone in the future until Rotax fixes their mess (fingers crossed), otherwise we just replace poor parts with more poor parts. I will also attach the link to the updated wiring harness installation from Rotax here too:
https://gorotax.com/information-bulleti ... -function/
I know that a number of us here at the club have suffered, or are suffering from issues with the new EVO Upgrades. I thought I'd post my problem here and I hope others will follow suit to enable any future issues to be diagnosed quicker based on other people's findings so far.
SYMPTOM
After installing my EVO upgrades, the kart ran great with no issues. In the last 2 weeks or so, I've been experiencing a loss of low RPM power exiting the two slow hairpins of turns 11 and 13 (running Clockwise now).
FAILURE
After trying a number of things to improve the situation, I eventually found that my issue was caused by the Power Valve (PV) staying open below 7600rpm. The reason this was happening was due to a broken wire at the connector for the PV Solenoid for me (see pictures). We have also seen the wire from the Ignition Connector to the PV Solenoid be damaged at the Ignition Connector too.
REMEDY
As the problem is part of the new wiring harness, I had to replace the complete harness to fix the problem.
Whilst trying to fix the low RPM power issue, I went through a number of things before finding the problem. When I first noticed the issue I observed the PV on the stand and I could see it opening and closing but couldn't say for sure it was 0% - 100%, so thought maybe it was never closing fully. Carb adjustments made no real difference, changing the exhaust packing, air filter, spark plug, re-building the fuel pump etc etc obviously had no impact either. I was always concerned that it was PV related and my gut feeling was that it wasn't closing fully below 7600rpm and Joey from Overdrive Motorsports mentioned that maybe the slide was sticking in the cylinder. After speaking with Joey, it appears that the earlier cylinders (mine is an '06) have a slightly different casting to the later ones ('09 onwards?? can someone confirm this year?). This means that with the new PV assembly, the body of the PV fouls on the cylinder and 'could' cause the alignment to be out on the slide valve and possibly cause some binding in the cylinder. The bottom of my slide already shows signs of wear on both sides of the underneath, suggesting this may have been happening with mine. I have filed the body of the PV since and also some of the cylinder casting to ensure there is daylight between the two. I believe this was found on a DD2 first of all.
Anyway, whilst I was running my kart on the stand 2 days ago, I observed the PV and noticed that it opened at 7600rpm ok, but was closing way below that at around 5000rpm, before eventually staying open all the time. I suspected the PV Solenoid had failed, so tried a known good one, which seemed to work initially, before doing the same thing. I then tried another Ignition module suspecting it may not be sending the signal to the PV Solenoid, but the same thing happened as with the solenoid. I am running on the 'Pressure' set-up for the PV and the way the solenoid works is as follows:
* At start-up, the PV Solenoid has 0V to it and it is open between the bottom, silver port to the side port which allows the pressure into the PV, thus opening it up slightly
* At 3000rpm after initial start-up, 12V is applied to the PV Solenoid from the Ignition module which switches the Solenoid to allow the pressure built up in the PV to be vented back through the side port from the PV to the open vent port on the top of the Solenoid, thus closing the PV
* During normal operation, the PV is closed below 7600rpm (or 7900rpm if you have both ground wires connected) and the PV Solenoid has 12V 'applied' to it from the ignition module with the Solenoid in the venting position
* When the RPM increases to 7600/7900rpm, 12V is 'removed' from the PV Solenoid and switches to the pressure position allowing the pressure from the Crank to be applied to the PV Bellows, opening the PV up
* As the RPM decreases below 7600/7900rpm, the procedure is reversed and the Ignition module 'applies' 12V to the PV Solenoid again, switching it back to the venting position which removes pressure from the PV Bellows, allowing it to close
Due to the ignition module and solenoid not fixing my problem, the only common part was the harness. When I ran my Kart on the stand again yesterday before changing the harness, I tried manipulating the harness around the plug connector to the PV Solenoid and I could get the PV to work from time to time. After the umpteenth removal of the connector, the wire above broke off, revealing the cause of all my problems. The copper wire inside had obviously broken some time ago, but the outer red insulation was still intact causing me to have intermittent issues as the wire would touch back together sometimes, allowing the PV to work on occasions. So, even though the harness appears to have fixed my low RPM power (track test not done at time of writing), it's nice to know 'exactly' what was causing it within the harness. Obviously, another connector with 2 flying leads would be all that was needed to fix this, but it should be a warranty issue for the harness anyway.
Sorry for the long post, but hopefully we can build up the info' regarding EVO issues here to help everyone in the future until Rotax fixes their mess (fingers crossed), otherwise we just replace poor parts with more poor parts. I will also attach the link to the updated wiring harness installation from Rotax here too:
https://gorotax.com/information-bulleti ... -function/