Mac's 99cc Predator build

Quenton Guenther · Jan 6, 2012

Hi wayne z,

I agree, raising the bar, might be counterproductive. If the time is invested to get the right drive ratios, the motor will have enough power to make a nice motorbike.

The jetting changes are totally dependent on the intake breather and exhaust system, and hopefully everyone won't start drilling out the main jet thinking it will make it run better.

I tested the motor with the stock exhaust system and intake breather, and found the jetting to be close [just slightly lean].

Have fun,

Mac · Jan 6, 2012

Wayne, looking for an aftermarket aircleaner to ret rid of that hidious black air box, think you could send me a linkl? I also have the flex pipe feom Quenton, the one for the HS49 with a hotdog muffler. I was only joking about the nitro and turbo... I like the torque for the big hills with me 230lbs on it!
Mac

wayne z · Jan 6, 2012

Yeah Mac, I knew you were joking. Nothing wrong with imagining posibilitys LOL.

I bought a pancake, pleated filter off e-bay that was meant for the HT engines from BGF. I heavily modified the adaptor plate (lathe, bandsaw) to make it work on the Preddy.
Gonna make my next one from some scrap 1/8" aluminum for endplates, longer bolts, and a small round pleated paper filter about 2" dia and 3" long,made for a Tecumseh push mower.

Quenton Guenther · Jan 6, 2012

Hi Mac,

I also knew you were joking about the nitros, etc. Just wanted to have some fun in the response.

It is very possible to make your own air breather. Use a "tuna" can, drill may holes in the side, and simply use a small piece of foam. I just recently viewed a breather made from an old "Turtle Wax" can. They drilled 3 holes in the bottom, one to match the carburetor opening, and the other two to attach to the carburetor. Next they drilled many small 1/8" holes around the outer edges of the container. They cut a piece of foam, and simply filled the container with the foam. The cover just snapped on, and the foam stopped the lid from "sucking" into the throat of the carburetor. Looks like it only took a few minuites to make, but looked great and worked well.

May hook a turbo to one of these motors in the future [just joking, LOL]

Have fun,

Mac · Jan 6, 2012

I may have been joking about the turbo, but it stays resident in my mind, for example:
I own 5 Subaru's(wife, kids etc) 2 of them have the DOHC 2.5, my wife's '05 GT limited Spec 3 has the same motor, but it's turbocharged(factory). The Stock motor 165BHP, Turbo motor 265BHP, INSANE difference, a family car 0-60 in 5.2 seconds. Unfortunately she doesn't let me drive it much... especially alone!! My point being free horsepower!! If we could find a tiny turbo (Garrett does make one) I'd bet we could all stay "legal" with a Honda/HS49 that would pull just as good as the Pred99, not to mention the possibilities with the HF99's!! Good news is ya dont have to pounce on it all the time, just there when you need it... I;m still thinking!

R/Mac

Quenton Guenther · Jan 6, 2012

Sorry it has been tried, and the turbo is too large [smallest one available]. A friend of mine Ron Dow almost got one to work on a seriously modified Whizzer [138 CC flat head], but the lag was massive and needed to travel "down hill" to aquire enough boost to reduce the lag.

Anyway increasing the power on the Honda or HS motor isn't a good idea as they tend to drop the rod at higher RPMs [above 9000 for extended length of time]. Several companies ship 4-stroke kits with insane ratios and had the pleasure of replacing motors [not us, as we use good ratios] because the motors needed to hit 9000 RPMs to go 28 MPH.

The trick is to add more torque and keep the RPMs within reason.

Have fun,

jbcruisin · Jan 6, 2012

You guys are killing me! I just now ordered on of these engines online. It's going in my blue bike.

Mac · Jan 6, 2012

Darn stuff is contagious!! Motor-Bicycling should be considered a level 5 pathogen, like anthrax or ebolie. Once ya got it, ya can't get rid of it, and if your (wives)/better-half's are anything like mine, well... it'll kill ya too!!

Quenton Guenther · Jan 6, 2012

Sorry Mac, but my wife won't let me sell anymore of my collection [Jay is the only one to obtain any of my personal collection], and thinks I should get a few more. Jay's wife bought one from me last year and gave it to Jay for Christmas.

Get her to start riding with you [may need to build one for her]. I gave my wife a new Whizzer in 2001, and I am still testing it for her, LOL. In fact it was her Whizzer that set the speed record in 2005 at Paducah, KY [only went 62 MPH then]. The last time I ran her bike on the "Roller Raod" it only managed to reach 68 MPH. I was even forced to take her bike to the majory of shows for the rides.

Have fun,

Mac · Jan 6, 2012

Quenton,
Just to let you know it's not impossible, read this:

TURBOKART

Or this little jewel:

http://www.chinese-parts-canada.com/turbocharger_fuel_injection.html

Quenton Guenther · Jan 6, 2012

Hi Mac,

The MBE version is the one Ron used on the Whizzer motor.

Seems the motor needs to be at least 200 CC or bigger to make it work well. I know of several 250 CC Ducati motors that used turbo chargers, but the turbo lag made them hard to use on most race tracks. They really did some serious runs on straight tracks [1/4 mile and road races with long straights].

After reading the articles, looks like it would take serious $$$$ to work out the details.

Have fun,

Mac · Jan 6, 2012

Thinking about repuropseing. Many aircraft that have environmental control systems(heat and A/C) have what they call a "Air multiplier" which is basically a turbochrger(Looks the same too), APU or engine bleed air spins the Hot section and the "cold" side is either blown over evaporators or is cycled thru "A, B and C" valves that cycle to create the orfice effect to cool the air(like discharging a CO2 fire extingusher) Anyway, I may have to get in touch with a friend at the Aircraft salvage place, but that is back burner stuff for now.

R/Mac

Mac · Jan 10, 2012

Back to testing,

Installed a 56T rear, (vice the 68T that I had with the HS motor), AX25 belt 2.5" primary, nice combo with the 29" wheels, top speed(new motor) 42MPH GPS verified, 25-30 cruise is so sweet. Thanks again Quenton for the help!! I did look at the Valve lash which was set at over .020" from the factory, went to .006" on both, allot quieter and of course a little more pull up top, due to "psuedo" More lift/less lash. I did notice there was no valve float at max rpm like there was before, now it's time to take it apart for some paint, lube inspection etc... Maybe an army theme?? Oh BTW, I did this test at 28 deg F., Brrrrr!!
More to come!!

R/Mac

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Mac's 99cc Predator build

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