How did you do that? Is there a way to adjust timing on these bikes after all?
I'm still chasing my decel pops. The little 'blat' I get when upshifting sounds pretty cool, but the decel popping on my bike has always been outrageous. I've done everything mentioned here for addressing that but am intrigued to hear of a timing option. My coast enrichers are fine, my EGR system is gone and plugged up tight and I've addressed all the exhaust leaks I've found. The only way I've been able to get rid of decel pops is having the idle set higher than 1100. But then I'm basically not decelerating either which, needless to say, can be scary when trying to slow down. 😁
I put an aftermarket ignition controller on my bike. I then ran some extra vacuum hoses to T the two vacuum ports together into a MAP sensor. The controller senses engine vacuum and adjusts based on load. Long story short, if you put the hoses and MAP sensor on like I did in the first link, the module is otherwise plug-in-play. I even left my factory controller installed in case something went wrong, but 1.5 years in I've had no issues with the new module. The rest of that "diary" is me waxing on about my discoveries along the way.
Here's the process for the extra vacuum hoses.
For reasons outlined in another thread, I have linked the two vacuum ports together. https://www.vn750.com/threads/ignitech-sparker-tcip4.106338/post-1293974 I noticed some rev hang. Pinching off the linking hose causes the RPMs to rise slightly. I backed out the idle screws from 2.5 to 3...
And here's my "diary" on the process of tuning the ignition.
UPDATE 5/3/2022: Stock timing with 8,700 RPM rev limiter now available for download! This provides a much cheaper option to replace the OEM ignitor. It also helps with hot-starts by driving the ignition coils harder during cranking. EDIT: For the sake of those reading this many years in the...
Overall, the change gave me a slight bump in MPG (2-4 more), which was the motivation for the project. Not fuel savings, but increased range on a tank. But the additional benefits are well worth it in my opinion. I bumped the idle timing from 5 to 7 degrees. This allowed me to close the idle a bit more to maintain 1100 RPM, giving more deceleration than before. With the settings I'm running, I pull the ignition timing back to 10 degrees after top dead center (which causes popping) BUT it also further reduces the residual power during deceleration causing an even faster RPM drop. The engine overall feels a lot more responsive. I set up a 2nd ignition table for when I'm running on choke. This controller can change timing tables with an external switch. It runs significantly retarded ignition timing in this mode, causing it to idle at 1500 on choke, as well as rev down almost as quickly as the original bike off choke. It makes it MUCH more predictable to ride on choke.