TheAkbars

2 hours ago, DannoXYZ said:

What's the purpose?

 

There's always RPM signal, that's how ignition-system works. Use oscilloscope to probe the pick-up coil on crank. If oscilloscope isn't regular go-to in your toolbox, this will not be "easy" project.

 

Really, only reasons would be to extract that last +5-10% performance out of engine over carbs. On CG125, you won't notice the extra 1 bhp. Or to tune for extreme mods such as turbo, turbo+supercharger, or turbo+supercharger+nitrous. All of which is much easier to tune with couple button-clicks of mouse when changing something like boost-level. But if you're staying with stock engine, factory carbs work just fine.

 

Example is this custom-built turbo barstool with Honda 160cc single engine!  Has SDS-EFI system, typically used on Lycoming aircraft.

 

Most people wouldn't notice difference with more lively partial-throttle response from 3D mapping of ignition. Here's links to Greg's really cool EFI conversions on Ninja 250 and Bandit 400:

 

https://www.ninjette.org/forums/showthread.php?t=34208

https://www.ninjette.org/forums/showthread.php?t=54500

 

http://forums.banditalley.net/suzuki-bandit-250-400/greg's-bandit-400-fuel-injection-project

 

 

Another Ninja 250 EFI turbo conversion and built his own dyno to tune it.

http://swarfman64.blogspot.com/2015/01/ninja-gpx250-turbo-project.html

 

Never, ever "easier" than carbs due to time and cost involved for minimal gains. Easiest is buying all EFI parts from similar bike and retrofitting to your own. Such as EU EFI Ninja 250 vs. U.S. carby Ninja 250. After U$3000 - 3500 in parts and expensive software.  Along with hundreds of hours in labour, you have bike that behaves exactly the same with similar output. Only when you start upgrading the bike with full-exhaust, cams and high-compression big-bore pistons, then EFI lets you adjust tuning easier and gain some little extra over carbs. In case of Ninja 250, it's an extra 5bhp over what carbs gets with all these upgrades. Again, will you notice this extra 5bhp? That's less than difference between clean vs. dirty carbs on Ninja 250 anyway. "Easiest" upgrade is to send your carbs to squirrelman for cleaning.

 

Megasquirt manuals are good reading for intro to EFI conversions and tuning: https://www.msextra.com/manuals/

Appreciate the reply, plenty of resources I haven't come across on my own. 

I should have also mentioned that, yes, I will be going bigger bore and higher compression. This isn't a project of practicality, but something to challenge myself and have fun tinkering with.

I knew there would be some form of RPM, I just assumed it would be a massive pain to access, but I guess I'm here for that. The extra single horsepower on a bike that's probably only putting out seven at this point would probably be noticeable.

Once again, thank you very much.

I sure hope I can temporarily ressurect this thread. I'm sure it's many times easier than dealing with a V configuration bike, but how much effort do you think converting a CG125 would be? I'm pretty sure there's no way of getting an RPM signal considering there's no RPM gauge on the cluster making load calculations difficult. This isn't for a practical purposes, more of a project I find interesting.

Edit: should mention that it's a '96 Brazil and is a CDI bike.