1981 SRX440 8K4 Ignition system

[NorthofSixty]

Looking for some help putting together an ignition system for the 81 SRX. I have an 8K4 CDI system from a 1980 SS440D. Does anyone remember whether the original 8K4 CDI ignition system on the 81 SRX (before the update) had the added weight on the magneto or was it the same as the 1980 SS440D which does not have the additional weight. I ask because the manual for the 1980 SS440D calls for an Hitachi F170-55 flywheel whereas the 1981 SRX440E manual calls for an F170-57. Hopefully there are still a few members around who busted knuckles on these sleds.

 

[sideshowBob]

On my 81 SRX I ran the 540 VMAX bottom end, flywheel, and CDI...the sled is still running strong. I also changed the carbs to 650 Polaris round slides with weighted deep float bowls and all the random unexplained piston problems ended.
Worked for me.

 

[NorthofSixty]

Thanks, switching to deep bowl round slides is probably a good idea. The fact that Yamaha moved to round slides on the VMax 540 is probably a good indicator. What size carbs did you run? I am currently running the 1981 updated 8R9 bottom end but with the first generation crank. I parked it years ago after the CDI crapped out and it would not rev up. I briefly borrowed the CDI from my brothers VMax 540 and she came back to life on the Dyno so I know it should run again. Was hoping to run it in next year's 660' snow drags but not sure whether to go with the original 8K4 set up or stick with the updated 8R9.