New test bike for my motor work.

Hello all out there in motorbicycling.com
Sorry I haven't been on the board much lately. Business has been good building bikes and motors. I had a crash on new years day, it was a dumb mistake and I broke some ribs and my collar bone. Slowed progress on the high speed projects but I am trying to keep the things going, With the help of my wonderful wife things are getting done again just a bit slower.
Anyway I was not sure where to post this bike. I built it to run motors and test piston designs, porting, pipe shapes, just everything in the quest to one day attempt a speed record. I have installed China girls, HuaSheng's, and 79cc Predator motors in these so I figured this one will in time probably see all those motors and maybe more so it's the best test bike for me.
The bike is a Kulana frame and fork, zero offset stem, almost flat bar, 24x3 rear tire on a simple free wheel rim, 26x1.125 front with a caliper brake, 5" set back seat post, short crank set, and no chain tensioners either side done with a half link pedal side, a lot of small adjustments, and a thin shim under the rear motor mount.
The motor is not the motor I build in house and sell. It is a cheap online motor traded in to me. I wanted to build a cheap kit motor to the best of my abilities and see how much power I could make. I did this as a reference point for when I get customers asking me to modify their motor.
The crank end play was decent and balance is not great but I wanted to experiment with making the lightest pistons I could and have them hold together for an acceptable time so this was ok for this motor. I brought port timing to the exact specs of my in house kits. I got the port shapes nearly identical to my best and developed some new techniques to get the same finish throughout the ports. Stock intake manifold cut and port matched, no head gasket and I worked the dome by hand until it cleared the piston at TDC, heavily ramped, notched, drilled and slotted piston, 3 prong kit spark plug, quite a few more little tricks here and there and what I believe will be a final shape to my own expansion chamber design.
I will really try to get more pics up and when I can get a little run time on it and get the rings seated in I will post up some performance numbers.



Lee Wommer
520-808-5731
Happy Motoring!!!

Excuse me but where do you get the knowledge of my experience and mechanical knowledge. I hold lap records as a driver AND builder at some of the most prestigious road race tracks in the country. The bike in the picture has a motor with the culmination of experience from a very long line of pistons and cylinders. That is the definition of development. I follow no one or no fad. I feed my family doing this and you are ignorant assuming that I should share my development methods and techniques on a public forum.
Let me help you though since you bring up high school and seem to have missed a few things. The reason your port matched intake did not work was not because you port matched it. It is because you do not know how to shape the transfers and combustion chamber to make the motor flow properly and were getting excessive reversion. The horrible stock intake blocked some of this and you misunderstood what was happening. It's ok though keep trying you may learn.
As the former technical advisor for the University of Arizona Formula SAE race team in the mechanical sciences and engineering department let me help you one last bit. The piston you are holding up in the photo that you tried to make an ash tray out of is seriously flawed. The nice holes you cut in it to hold a cigarette are positioned all wrong. They will only make it hard to empty and clean. Try making them smaller and more efficient, this will make it more aesthetically pleasing and easier to clean.
Happy Motoring

I am working on building a dyno for more accurate testing and comparison but need more time to finish it. So without hard numbers on a dyno I am truly guessing on power. I can take some decent guesses though based on improvements over stock and what other known power outputs will do in similar situations. My latest motors are getting near triple the power of a properly running GT-5 geometry 66cc kit motor.
You are right that less can certainly be more. My porting is not substantially larger than the largest of the stock ports on the better cylinders. While I said strongly that I follow no one, I do try to learn from the best. One example is I knew a motor builder whose CR450F motors could get the hole shot on factory Honda race bikes. THAT is someone you pay attention to when he shows you port dynamic secrets. He actually added metal in certain areas of those cylinder heads. Now I don't add metal any where, but making big power with one of these China Girls is about closely studying the flow pattern. Not punching out the ports as far as you can.
I am more than happy to help people in here and spent many late nights trying to figure out problems people were having and helping them solve the issues.
For now I am chasing 3 records though and don't intend to give away some of the things I discovered thru a lot of studying and trial and error. I will say there is big power to be made in the transfers and combustion chamber. If you think outside the box there is a way to make huge gains not by trying to increase flow but by perfecting and directing it. This will result in greatly improved flow AND when you get it right nearly eliminate reversion.
I have a several other carbs but work almost exclusively with the stock NT carb. At one point on my first motor I was able to gain about 2mph on the top end with an RT carb but it didn't work well overall so I modified it to use in my dual carb nitro/methanol set up and that's where it will stay. Just get the jetting right, make sure there are no vacuum leaks and the kit carb works well on these. The intake is far from perfect but the length seems about correct and there is room in the last 2 or 3mm before the head to shape it all the way out for a good gasket match. As far as the extended Z manifold I have not tried to make big power with one but have used them a couple times on builds that were entry level bikes and they ran fine with no noticeable drop in power on stock porting.

So far my dyno project is on the simple side. Really just to load and test. What I am setting up is a bicycle wind trainer ducted to blow on the cooling fins. I have a need to put electric motors under load for testing also so the project is two fold.
I have a tricky way of flow testing in two strokes. I will probably give it away with this big hint. It doesn't involve air but I got the idea from scale wind tunnels that don't use air ha ha.

And I like the GPS on a flat road dyno that you have used the best. The stationary dyno is great for break in and specific loading and testing. Not to mention when there is snow outside ha ha. But numbers, bar graphs, horsepower/torque claims can be useful tools and stuff to brag about BUT the race track or GPS on a flat road is all that actually matters. I do not and will not say how fast my test bikes go. I'm leaving that for when I call Guinness asking to make a record attempt. I will say the last China Girl I built for a customer asking for a fast bike gave me a budget of $650. He weighs 270lbs and is a personal trainer. The bike hits almost 50mph with HIM on it thru a 44 tooth rear sprocket and power wheelies thru the mid range if you don't lean pretty far forward.

Steve, I don't get mad easy and never feel the need to call out my credentials or justify myself. That said your first post in my thread hit me quite the wrong way ha ha. reading your last entry though I say to myself anyone who has flowed water thru a China girls ports looking for what we were looking for can not be bad. Maybe just too similar to me ha ha. Your philosophy in helping others is also admirable. As well as your thoughts on winning.
I am mostly just competitive against myself but find inspiration in others more than a drive to beat them at anything.
The real big progress I made with the China girl is thru the transfer, into the chamber and right to the plug. Think and work all the way to that point and there is big power there, the rest is refinement once you find that shape.
Glad this thread is off to a better foot.
Cheers

Well I am getting some break in on this motor finally. I have been having trouble getting a stock clutch not to slip under wide open throttle. I knew I would have to deal with this issue but thought I could get more out a proper cleaned and prepped stock set up. I have built one other motor close to this and the clutch held fine. I just want to put more energy into actual speed than chasing my tail with stuff like this. Oh well,if it gives me much more trouble I will have to try some different pad materials and maybe even a better spring.