4-stroke variable CDI


New Member
May 28, 2019
I've seen countless videos and threads/posts on the internet about 2-stroke CDIs but very rarely anything about 4-stroke CDIs.
All of these are "performance" parts as well, strictly for improving engine performance.

Because of the laws in my country, a motorized bike may not be faster than 25 kph (~16 mph) when used on public roads and spaces. It is also required that the engine is limited to this speed by some means. So just driving slower is not enough.
Thus, I want to be able to limit my bike when on public roads/property and de-limit it again when I'm not. So I don't run into trouble with the law and lose my ride or worse.
I've seen variable CDIs for "Normal" mopeds but these have sockets that I do not see on my Huasheng 49cc 4-stroke.

So, my question is if there are any variable CDIs for 4-strokes or if there is a way that I can attach/use a variable CDI for a "normal" moped on my motorized bike?

Best Regards


Well-Known Member
May 26, 2008
Do you have a link to a variable cdi? Since your worried about legality of the motor size why not just use a honda 35cc 4 stroke? About 20mph is all you'll go and about 1.3hp. Would that be legally close enough where you are? If not buy the 35cc and put factory honda 25cc stickers on it...…………..the 25cc would be a gutless wonder.


Well-Known Member
May 2, 2007
I've never been a fan of ignition-based rev-limiters. They end up causing fuel to wash the cylinder walls if you spend a lot of time on the limiter, which wears the cylinder bore to wear quicker and not to mention more carbon build-up. All bad things on a little 4-stroke and it's limited oil supply; but you could in theory make your own electronic rev-limiter connected to kill switch by using a tach and a switchable circuit.

I've limited my Huasheng's throttle stroke for years to help keep my shift kit and 5-speed hub gears safe, because the system is capable of so much torque. Easy to set up with a trigger throttle by changing the mount angle with a shim or on a twist throttle by limiting the twist action. Bad idea in hilly areas tho, without pedaling.

Dunno if either option is legal where you are, but that's my coupla pennies.


Well-Known Member
Aug 11, 2018
Get a speedometer check how far you gotta throttle for 16mph and home rig something so it won't go past that.... I used a few brake caps on the cable for a kids bike so he couldn't go more then half throttle