Who knows pit bike engines?

A while back I bought this '71 CL70. Did a bit of a "rustoration" on it and had the original engine built out to 117cc. That was a fiasco....it blew up three times and I pushed the bike to the back of the garage.

My original plan was to do a pit bike swap. I'm getting the itch to do something with it again. I'm leaning towards a Piranha 140cc, a.k.a. the YX 140 engine.
I read about upgraded carbs, bigger exhaust needed, charging system, etc. Then there's the whole converting to 12V and CDI thing. Splice into the existing harness or just swap in a complete new harness? And what about an oil cooler?

I'd like to be able to cruise easily at 45-ish MPH and occasionally hit 50-60 for short stretches when needed. I've already installed a 46T sprocket on the rear and, if I remember correctly, I was using a 17T up front.

Can any of you walk me through doing a swap that would be kick only but still run lights for the street? The CL70 is titled and is street legal. I'd like to be able to eventually go out and beat up on a Grom. Or at least give them a run for their money!

You can buy the engines ready-to-run. All they need is gas and a 12V battery. The engines are self contained for CDI, charging, etc.

You are responsible for making the bike stable at 60, and also able to stop, steer, etc.

It is usually cheaper to buy a used mini moto that may have chunked forks, then to just buy an engine.

The only electrical you would need to sort out is the lighting, near as I can figure. Stick a 12v battery in the bike, I guess a 12v regulator/rectifier, and some 12v light bulbs. All the switches and wiring will be fine with 12 vs 6v. Just don't want to blow out the bulbs.

Engine should charge the battery and the regulator will feed the bike with 12v power for the lighting.

Am I over simplifying this? I'm actually considering doing something similar, as I have a little CT90 that I'd prefer a proper clutch 5 speed transmission in vs. the semi-automatic 3 speed or whatever nonsense is in it now. I want my daughter to learn how to shift, and I'd prefer a more standard experience on it too.

I've been eyeing the engines over at TBoltUSA. Where were you looking? They come equipped with the electrical and carbs. And Matt from Sparck Moto can help with some of the 6v-12v conversion I'd bet.

http://www.sparckmoto.com/

http://tboltusa.com/store/piranha-140cc-engine-br-fits-pit-bikes-and-other-minis-p-660.html

Actually reading the TBolt site, the YX140 has an 'aux output' for lighting. So just plug your lighting harness into that and swap the 6v bulbs out. Should be good to go. Maybe you don't even need a battery at all - I guess they run a PMA and generates enough spark to start the motor, or maybe they have a capacitor built in.

I'm looking at the T-Bolt engines, too. I shot them an email last night asking some questions.

I've been doing some Googling, but I get as many questions as answers. I've seen some wiring harnesses and conversion kits for the CT70, but not the CL. I'm not sure how close the two wiring harnesses are, but at under $60, a new wiring harness looks tempting. Of course, I could just splice stuff in and change the bulbs.

I have read that some of the outputs for lighting leaves a little to be desired and there's an upgrade....alternator or stator windings or something?

I also have questions about whether or not the stock CL exhaust would work. Again, I've read conflicting opinions. Same thing about carb upgrades. And why does T-Bolt charge $100 to upgrade to a Mikuni VM26 when the're all over eBay for less than $30? What's the difference? And there are videos on YouTube showing guys tearing up the town with an even cheaper Molkt carb. What the heck is that? Chinese knock off?

The early CT70's don't have blinkers so when you look at crossing a harness over you will have to go for at least a 79 or early 80's CT. The 90's versions also have blinkers but there is less of a chance that you will find an aftermarket harness for them(they are 12volt too). I have a 1970 CT70 and I don't think that the speedo has a back light so that may be another difference. Otherwise the CL has the same engine as the CT.
The GROM top speed is 61 mph so you may need another gear. Lol.

I had it up to 50+ before I blew up the 117cc.

62 mph is going to have to be your goal. All jokes aside, that is a cool CL that you have.

Agreed, but if I can at least take them out of the hole...

I have 17/46 gearing combo. That's a 2.71 ratio and is supposedly good for cruising at 50-55 mph and capable of more. I just need the engine.