Illinois regulations are a P.I.T.A.

There seems to be some confusion here ... In IL a motorized bicycle is NOT a motor vec. And can never be reg as a moped as, it has no manufactures fed hyway sticker.
If you build a two stroke and follow the bicycle laws ,you should be fine !
Please read : public act 096-0125
And 625 ILCS 5/1-140.15 and the related laws

His concern voices the same thoughts I have. Virtually none of the common gas engines used on bicycles meet the IL Motor Assisted Bicycle regulations including producing 1 HP or less and not being capable of exceeding 20 MPH on a level surface with a 170 lb rider, etc.

The laws were written as a virtual copy of the Federal statute which only applies to electric motors on bicycles; and then the state kept the 1 HP limit and the 20 MPH speed limit and applied it to gas engines.

I'm very glad most motorized riders in Illinois are not being ticketed for violating the statute as written. But if you live in an area where a policeman or the local States Attorney want to make an issue of it you are screwed.

The law as written is pretty much impossible to comply with using a gas engine. As someone who cannot afford tickets or legal trouble it really bothers me that the law is almost impossible to correctly obey.

Well you have a few good points ,but i feel like your over thinking this alot...
I was involved in argueing with springfield when the law was in the works. The local repp seemed to understand that motor manufactures claim a lot more horsepower then there product will actualy produce (remember the lawmower lawsuit from a few years back)
So a few things to concider ... There is no deff of horsepower in il vec code? The scales of displacment (cc's) and horsepower messure diff things and thers no mention of cc's in il law? What they did do is come up with a horsepower like system ,that cant be meet in real world setting? If you wana pay (more then a bike is worth ) for a dyno test for a bike , following the SAE deff of shaft horsepower , the motor will fail to turn with out human assistance = zero hp ?
What we do have is a law that allows one to operate this type of "device" on Il roadways .
Each rider has to be treated as an indvidual ,so the cops have to catch YOU Breaking a spefic law! Once again it's not really what you ride ,it's how you ride! As far as i've been able to determine there is not a single cop in IL who is trained in motor assist bicycle inspection? And prob never will be .... So it all depends on your actions , if you ride cool and follow the bike rules there not gona stop you by the side of the road to try and test horsepower?
Many of us argued for years to win ourselfs the rights we currently have in IL ,everyone knows the law is flawed ... Oh well its the best they could do.
If you worried about takeing the "risk" of rideing in Il because of the way the law is written or you have other intrests to protect maybe this hobby is not for you?
Just remember that when they see you rideing around ,they see all of us in your actions !

I would say it mostly depends on your local police and how you ride. Sometimes city ordinance but ordinance can be overruled by state law if your bike truly complies with the state laws.

If your in Decatur your out of luck unless you can prove it complies with state law http://herald-review.com/news/local...cle_2504c8b0-2956-599a-b44c-4fc4fef2a6a6.html

A local cop tried to ticket me once when I first built mine but I showed him a copy of the state law and acted completely unconcerned. He said he would get back to me after he looked into the law more, that was more than two years ago and I have not been bothered again. I'm not sure how they will react to the 79cc predator powered trike I'm building though. I am gearing it to max out at 20 with the governor still connected in the beginning that way I comply with easiest to test part of the law.

So if your really worried gear it to max out at 20mph and see how it goes from there. If your using a china 2stroke on 26in tires a 56 tooth rear should put you at almost exactly 20mph tops. Though that would probably make it easy to over rev the engine past 6000rpm, taking you over 20mph and blowing the motor if you stay over 6000 to long to often. Ok on second thought probably not the best solution with a 2stroke kit.

I think the only way to truly comply with ILL state law would be to use a 33cc Honda or Robin/Subaru with a 19.4:1 gear ratio on 26in wheels. I think those are rated at 1.1hp but are the closest to 1hp I know of.

It is how you ride not what! That seems to be the prob in decatur ,theres to many hahoos riden around with no concern for others...
And btw that article is cramed with miss quotes and outright BS . Ccs and horsepower dont mix at all ,its like saying your testing a cars breakfast cerial output .... Man that hacks me off!