The Monster Energy Cup went off a few months ago. I have watched that race a hundred times, thanks to TiVo. I can slow down my favorite parts of the race and fast forward the commercials. The Monster Energy Cup was the first time I really got to see the Super-Mini class in action. I can’t ever remember seeing these guys on TV before. Riders like Adam Cianciarulo and Cooper Web are unbelievable on the little bikes!
The Monster Energy Super-Mini class is for kids 15 and under riding 85s, 100s, and 150R four strokes. The rules are pretty loose in the Monster Energy Super-Mini class. You can run big wheels, 16” rear and 19”front. On the two strokes, you can run up to 112cc with aftermarket pipes, suspension, wheels, etc. Pretty much anything goes.
Since I am a little bigger now, I decided to convert one of my KX85 dirtbikes into a Super-Mini. Basically, I would need a bore kit, aftermarket pipe, larger rims, tires, tubes, and a longer swingarm. The hardest part of the whole conversion is increasing the size of your engine. If you are working on a KX85, you can get parts from a KX100. The KX85/100s have not changed much, if any, since 2001. One way to convert the engine is to order the complete top end from a KX100. If you do this, you will need everything. The piston, cylinder, power valves, and cylinder head will all have to come from a KX100. If you get lucky, you might get a whole top end for cheap on e-bay. There is a problem though, the stock Kawasaki chrome in the bore is not very good and the porting is aimed at beginner level riders on the KX100 cylinder, so it won’t rev out like most racers want.
I found a great alternative that ended up not being that expensive for what you get. Eric Gorr at Forward Motion has been building two strokes forever and knows how to make them fly. He can take your stock KX85 or KX100 cylinder and bore it to whatever piston size you want and then re-plate it with high quality U.S. chrome plating. The best part is that Eric can port the cylinder for bottom end power, mid range power, or dogs howling in the neighborhood top end power. I chose top end porting because I like to really rev the two strokes out. This is the first engine I can remember that ever rev’d high enough for me! Make sure you check the right box for your riding style when you send your cylinder off. Usually, bottom end power is for indoor riding and vet riders, mid range is for intermediate riders and top end is for big outdoor tracks and expert level riders.
For the piston, I went with the Vertex KX100 piston. Vertex makes pistons that will get you all the way up to 112cc, but I went for the most reliable set up, since I ride everyday and rack up the hours. Since my KX85 was a $500 Craigs List beater to start with (I am funding my own racing career) I decided to install a new crank while the engine was apart. Hot Rods Cranks makes a 2mm stroker crank that adds 4 more cc, depending on which piston you go with. Just remember to tell Eric Gorr at Forward Motion to cut the head to go with the stroker crank. If all this engine talk sounds complicated, it doesn’t have to be. Just go to www.eric-gorr.com, they will give you the options for building an engine that fits you. You can even send them your complete engine and have them do all of the work.
A couple other items that have become standard two-stroke parts are the VForce Reed Valve System and a Fluidyne radiator to keep the bigger engine cool. I also ordered a Pro Circuit pipe. The pipe all by itself adds power everywhere with a nice top end hit. Pro Circuit makes two different silencers; a short one for bottom end power and a long one for top end power. So make sure you get the right one for your riding style.
To complete the conversion to Super-Mini I needed bigger wheels. I ordered up black Pro Wheel rims (16” rear, 19” front) and longer spokes to match. If you are afraid to re-spoke the wheels (it’s easy after a few tries) Pro Wheel can do it for you or you can get complete wheel sets from them. To finish off the wheels, I put on my favorite Dunlop mud riding tires, since I live in Seattle. Now I needed a longer KX100 swingarm to match the larger wheels. This was pretty easy to find on E-Bay. There were at least five of them listed on there at once. I ended up getting a nice one for $40.00 with the chain guide and good bearings.
The last thing I did to the bike was add the BBR Monster Ghost Graphics. It went from looking like a $500 beater to new and modern. How does it ride? Incredible! The two biggest changes were the wheels and the port job. The big wheels and longer swingarm let you go so much faster. The bike lets you just plow into big bumps. Starts are a lot easier with the big wheels and the rear wheel really hooks up. The engine is amazing, it pulls hard everywhere. Where the stock engine used to quit making power, this one really comes alive. It pulls every gear much longer.
At 104cc, this isn’t the biggest super mini engine set up you can do, but it is fast and reliable. If you want to build your own Super-Mini or just rebuild your two stroke, give these guys a try:
www.craigslist.com – “2005 KX85 – Needs new front fender, bars, and levers. $600.00 or best offer.” Paid $500.00
www.eric-gorr.com – cylinder boring, plating, porting, power-valve and head mods. Vertex piston and gaskets. $400.00
www.vertexpistons.com – KX100 performance piston kit $153.70
www.hotrodsproducts.com – 2mm stroker crank $189.95
www.mototassinari.com – VForce reed valve system $148.95
www.fluidyne.com – KX85/100 race radiator $221.99
www.prowheelracing.com – 16 ”rear black rim $128.00, 19” front black rim $110.00, 16” rear spokes $65.50, 19” front spokes $76.50
www.procircuitracing.com – Works pipe $229.95, 304 silencer $119.95
www.ufoplasticusa.com – Black plastic kit $139.95
www.fusiongraphixxs.com – BBR custom Monster Ghost Graphics (call for pricing)
www.eric-gorr.com – Complete engine service. If you are afraid to rebuild your own engine and want an expert to do it, just pull it out and ship it to Eric Gorr. Starting at $795.00 including parts, he will do everything right and ship it back to you ready to go.