ok, cleaned up motor and degreased it, took 1 hour and almost 2 rolls of paper towels. Ready for paint this weekend...

btw...happy 8000 for me!!

 

wow, grats on 8,000!!!!
can't wait to see this bike at a meet.

 

Getting the bike put back together over the weekend, so much for doing it by myself..hahaha

 

When I was in high school there was this mini-bike racing track not too far and a lot of people raced there on those little crotch-rocket looking bikes. The problem was they cost over $3000 (the REAL race bikes- 100% hand-made in Italy, have 13-hp water-cooled 48cc 2-strokes singles) and I wanted to race but I didn't have that kind of cash. So I went to a PepBoys and got one of their little bikes with a 49cc air-cooled 2-stroker for $300.
I found some part suppliers, converted the front to dual hydraulic disc brakes (does stoppies on a dime!), new Walbro ported and CNC'd racing carb, KX50 FMF 2-stroke racing pipe with expansion chamber, some porting work on the ports in the 2-stroke engine sleeve, Weisco "Blue Bird" big bore kit that put it at 72cc, and a few other things. I got it to well over 14-hp I'd say, and it would ride a wheelie all the way until it's 42-mph top speed! I had full plastics on it, too.
I hacked the stock steel frame and welded on a lighter rear subframe. The thing was bad. There is actually a national race in Vegas every year for this mini bikes (not the pit bike like you have, but I have seen them race).
Here's a good place for performance parts: http://www.partsforscooters.com/
Here's another one for good parts: http://www.monsterscooterparts.com/
PM me if you want any more help! This thing is HOT!!

 

Oh and I forgot to mention- your top speed is super-dependant on your counter and rear sprocket sizes! Also tire/wheel diameters play a huge role in top speed. It's hard because the higher your top speed the slower your acceleration.
I had a friend which a pit bike like yours, with an alcohol-running 84cc Briggs making over 30-hp (calculated with math: took weight of the bike + rider then plugged it into the formula for it's 1/16 mile run and trap speed) and it was qicked fast. It could do 85-90-mph, but it was slow to start. He eventually developed an automatic 2-speed gearset with varying diameters that was really cool.

 

thanks chicken. I'm currently working with this guy, he has 5 mini bikes with 12-15 hp honda motors that do 80-85 mph as well. After im done with this crappy 3 hp briggs motor im having buile me a honda motor. Bone stock with that honda motor it should be able to do 40-45 mph.

 

yeah, the Honda 4-strokes are good. But there's a lot more parts for the Briggs engine out there. Or look at JEGS and their JR Dragster alcohol-burning single cylinder Pro Bracket race engine that makes over 60-hp and is only $1500 haha.

 

Growing up in the 60's I pretty much spent all my time focused on mini-bikes and your thread brings back good memories. I had a Fox minicycle with disc brakes and chrome tank, and can remember how much I loved that thing. Rupps, Bronco's, Steen, Gemini, and Bennelli come to mind. I dreamt about owning a Benelli volcano mini with the 185cc engine...wow a lot of power for that little chassis. I still have two CT70's and a QA50 sitting in my garage waiting to be restored.

This thread makes me want to get off my dead **** and work on them... . Once I get em going if I can find a shriners Fez the dream will be complete!


Thanks for sharing man!

JR

 

update from this weekend. Had to remove the old shoe brake system and had it converted to a manual lever brake system. Picking it upt today after hopefully

 

Ok here are some of the pics. All the major components are finally done. Now I just have to work on the smaller things.

 

pretty pimp Xdubb. Now lets see a vid of you wipping out on it!

 

im still busy trying to work out the smalll bugs that come with it when you restore a 40 year old bike..hahah