- Location
- Louisiana
I have a 90 superjet with upgrades including 62t case and cylinder with aftermarket head. It has GroupK ported cylinder, single 44 sbn carb with Coffsman exhaust and aluminum water box. Previously had a Dale's bad attitude CDI with stock Yamaha coil.
I've only ridden it a few times since purchasing it many years ago. On the second time out I noticed that it was surging under acceleration but was fine a wide open throttle. I adjusted the low speed circuit but didn't help. Checked plugs after riding and the color looked good but they were wet. Next time out I changed plugs and fuel but the problem still existed. Did compression test (both 167 psi) and checked plugs for spark. Both plugs had very weak spark. Had to shade plugs to see the spark.
I replaced the Dale's CDI with a new unit purchased off eBay along with a new 750 Kawasaki coil. Checked spark again and it had no improvement. Put another new set of plugs in and rode it again. Same outcome but now after it's ridden for about 15 minutes and a wot pull is made it will shut down.
I pulled the carb this week and went thru it. I found nothing that I think would be my problem. The pop off pressure was 15 psi and as per Group K website it should be 25-35. I reset it to 27 psi and pulled the intake to check the reed's while the carb was off. Reed's looked fine and installed the carb but haven't ridden it since. I changed all fuel lines too.
I checked the charging coil and lighting coil voltage thinking this is the only thing that I can think of that's left to change. I don't remember as I'm writing this which was what but one measured 3.9 volts and the service manual limits were 4.0-5.5. The other measured 29.0 and service manual limits were 30-50. My readings were done on a cold engine.
I'm thinking of buying a stator assembly but after reading thru some of the post on this site I'll need to know which flywheel is on my engine. The original CDI was color coded and terminal matched to my stator assembly wiring harness. The new 62t CDI that I installed had a couple of backwards (male to female) terminals so I'm leaning towards a 61x flywheel and stator...
What do you guys think I should check or replace next?
How can I know for sure what flywheel i have? (61x or 62t)
Thanks for any help in this matter.
I've only ridden it a few times since purchasing it many years ago. On the second time out I noticed that it was surging under acceleration but was fine a wide open throttle. I adjusted the low speed circuit but didn't help. Checked plugs after riding and the color looked good but they were wet. Next time out I changed plugs and fuel but the problem still existed. Did compression test (both 167 psi) and checked plugs for spark. Both plugs had very weak spark. Had to shade plugs to see the spark.
I replaced the Dale's CDI with a new unit purchased off eBay along with a new 750 Kawasaki coil. Checked spark again and it had no improvement. Put another new set of plugs in and rode it again. Same outcome but now after it's ridden for about 15 minutes and a wot pull is made it will shut down.
I pulled the carb this week and went thru it. I found nothing that I think would be my problem. The pop off pressure was 15 psi and as per Group K website it should be 25-35. I reset it to 27 psi and pulled the intake to check the reed's while the carb was off. Reed's looked fine and installed the carb but haven't ridden it since. I changed all fuel lines too.
I checked the charging coil and lighting coil voltage thinking this is the only thing that I can think of that's left to change. I don't remember as I'm writing this which was what but one measured 3.9 volts and the service manual limits were 4.0-5.5. The other measured 29.0 and service manual limits were 30-50. My readings were done on a cold engine.
I'm thinking of buying a stator assembly but after reading thru some of the post on this site I'll need to know which flywheel is on my engine. The original CDI was color coded and terminal matched to my stator assembly wiring harness. The new 62t CDI that I installed had a couple of backwards (male to female) terminals so I'm leaning towards a 61x flywheel and stator...
What do you guys think I should check or replace next?
How can I know for sure what flywheel i have? (61x or 62t)
Thanks for any help in this matter.
