Danny, that is awesome that you and your son built this...I am diggin the creativity!
Although I came across as an A-hole in your 79cc post, I will stand by my statements. Teaching young kids about safety is paramount. Stephen seems to know his stuff, but did not help you with your exhaust. You have a thread looking for more power, but your exhaust looks like the underside of my sink! It is obvious that you have some welding skills, what happened to the handlebars from the bike? They would make a great header for you! You have way too much weight hanging off the two little studs in the head...it needs support, but ditch the pipe...you need more power, right? Exhaust gasses should go out the rear of the vehicle. It looks like lots of fun and we don't want anyone to get sick. Stephen, would you like to tell Danny about the dangers of teflon tape burning and the noxious gasses they give off? Please do!
In the other post you never mentioned this cool buggy, so all us ding dongs on a minibike site assumed that is what we were talking about. You have a lot more weight here and the ability to carry more people. Your 79cc, no matter what you do, will not do what you need it to. You need a bigger motor. 3600RPM is the same no matter what motor you have. Top speed will be the same, you will have the ability to do more work at lower RPM's, which is what you need. If you gear it lower, you will have to scream the guts out of that little motor to maintain the same 20MPH. Even the guys that build screamer motors are often disappointed by the performance because they are looking for the big number at the top of the RPM range which kills your low end. Unless you had a gear box, you cannot have it all! That is why the newer cars have 8 speed transmissions...it allows them to have more low end with the economy at the top. Maybe keep an eye on your local Craigslist and see if you can find a used snowblower with a good engine and a bad auger. Lots of guys here find those cheap and rob the engines from them. For what you will spend trying to get some zip out of your motor, you could have rebuilt a bigger motor!
I am truly trying to help you. I am an A-hole and I am filled with enthusiastic sarcasm! My apologies for offending, but I think I have basis in my statements. Get the teflon off that pipe please!
