Race bike

[graydog8josh]

Wanting to build a competitive race bike. I have lots of questions.
The socal races what is the average speed those 66cc bikes are going in the pro class?

What about rider weight?

How much do the bikes typically weigh that race?

Are they typically single speed bikes?

 

[MotorBicycleRacing]

Are you going to be at the June 1st SoCal Motor Bicycle Racing 2 year anniversary race?

If you want to set up a racing series in MS I will help you.

Here is the PRO CLASS starting line on the April 13th race on one of the heats.

So far all the bikes are single speed.

 

[magrider]

Graydog, I can only tell you about myself. My china bike was clocked at 38 mph going uphill at the grange, 2500' above sea level, probably 90-100* 2 yrs ago. I'm pushing 200# and my bike weighs in at 65#, it is a single speed. That day I didn't have the fastest bike, there was another one clocked at 41mph.

 

[graydog8josh]

I want to get our university on the map in the motorized bike scene. I might look at local tracks to see if they are interested too. But i think it would be good publicity to take a mississippi state bike out to the races. I dont know the details but i would like to get a racing bike built this summer and brought out to a race, june is pretty ambitious but possible, but its goign to be hard to get a big
group ready for june.

 

[bairdco]

on the 1100' long straight at the grange the fastest two stroke chinas were clocked at around 43 a while ago. jim rust's bike is probably faster now. that straight can make the all the difference in a race. you can be quick as heck through the corners, and then blown away in a drag race.

the racers are all shapes and sizes, as well as the bikes.

speaking for myself, i'm 135 and my bike is around 60lbs.

on the grange track you need to find the balance between a good top speed in the straight, while still being able to get out of the slow corners fast.

i'm still trying to find that balance...

 

[graydog8josh]

my 4.5 arrow motor seems pretty fast to me, but ive only clocked 33 before i backed off. it gets so loud and wobbly at that speed, i think on a race bike build things are going to have to be tighter to be able to be smooth at speeds like that.

I guess ill have the month of may to smooth things out. Taking all the gaps out of the mounts making sure everything is perfectly lined up and balanced.

 

[bairdco]

the basics for a vibration-free bike is keeping everything tight. anything that can move will cause an oscillation.

when i put my motor on magrider's bike i tested it with a stock gas tank loosely mounted and the bike vibrated like crazy.
tightened up (or removed completely) and it went away. even custom, in frame tanks can cause a vibration. the tank is one place where rubber or silicone or some other soft mounts actually help, but it still needs to be tight.

a simple test is lean your knee into the tank when the vibes start, and see if they go away.

motor mounts should be secure as possible. no rubber mounting, and welded brackets to the frame if possible.

anything hanging, like an exhaust pipe will transmit vibrations, too.

loose chains or poor chain alignment, same thing.

racing a shaky bike at full throttle for 10+ laps is no fun. it's rough on the bike, and tires you out.

33 ain't gonna cut it in the big leagues. you'd have a hard time competing in the stock class...

do some research on what the other guys are doing to figure out what you're missing.

 

[graydog8josh]

I don't see myself as a big racer, im more into building something fast than actually breaking the sound barrier myself. But i threw on the kenda qwest tire today and decided to make myself believe i could go faster. went 36 and it was a lot smoother without a dirt tire in the front. My hands are still tingling though, i probably need to invest in some better grips or gloves or something.

 

[magrider]

Gloves are required for racing as well as other safety equipment. Most racers use Maxxis hookworms 26” great tire, holds your line and doesn’t fly apart. Renthal makes a good gel grip

Like Baird said, finding the balance between top speed and corner speed is crucial with a single speed.

Maybe consider the Oct. race it’ll be cooler, maybe in the 80’s, June will be well into the 100’s it’s in the desert, no water to be seen, tumble weeds everywhere, and it’ll give you more time to get other racers together to make the trek

 

[MotorBicycleRacing]

Maybe consider the Oct. race it’ll be cooler, maybe in the 80’s, June will be well into the 100’s it’s in the desert, no water to be seen, tumble weeds everywhere, and it’ll give you more time to get other racers together to make the trek

Wow, sounds like you are really trying to discourage Josh
from coming with some exaggerated BS. You are painting
a rather bleak but inaccurate picture.

June 1st has an Average temperature of only 83*
with a 54* average low overnight.

The Record high for June 1st is 95*

Last year 2012 June 1st was 87*
In June 2012 the max temperature went from a max of 95* all the way down to 77*
June 2012
2 87
3 84
4 78
5 77
6 86
7 93
8 87
9 80
10 84

June 1st 2011 was 77* with a 69* on June 8th

June 1st 2010 was 73* with a 68* on June 9th & June 10th

SoCal Motor Bicycle Racing has never had an event where the
temperature was over 100*

It doesn't get really hot at Grange until late June or July.

There are no tumble weeds, lol and even when it's 90* there is a
cool breeze in the afternoon.

 

[bairdco]

i say if you've got the time and the money and you think you're ready, come on out.

i also say, if you're not ready, don't rush it. it's a long way from missouri just to sit in the dirt with bike problems.

if you could make a little vacation out of it, even better. not much to see in the victorville/barstow area, but you're a few hours from vegas, laughlin, or the beaches.

and it may not be 100 degrees, but add a helmet, leathers, gloves, pads, and no shade, and 85-90 turns into hades real quick.

Neil, at the next race, i might have to stand next to you. the only "breeze" i remember is the one that rips through the pits every afternoon and knocks over everyone's bikes and ez-ups...

 

[graydog8josh]

if i were able to come up wiht the funds to bring a few bikes out there i would definitely bring someone wiht more cajones than me in the going fast department. Heat is not an issue, we'll drink water before we get there, and we'll collect all the tumbleweeds and build a shady shack out of them. I really dont want this just for myself, i know we have a small community that likes this idea of motorized bike racing and wants to go fast and wants to represent the university talent. I just gotta get the school and the mechanical engineering department on board and get it funded and/or sponsored. Will there be press out there, you did say it was the 2 year aniversary.

 

[magrider]

That’s a great attitude, and supporting the community is always encouraged, get your school on board even better. Just as easy to check weather.com to see temps in June, and google maps to see what is around the track. grange race track, 20455 Central Rd Apple Valley, CA 92307

 

[48ccbiker]

Everyone uses one speed because the multi-speed setup sucks about 8% of your engine power with all the extra gear. If you are serious about racing you should do as much of the following as possible:
balance the engine
more compression
better carburetor
better CDI
expansion chamber

 

[48ccbiker]

Turning one of those sloppy chinese 66cc engines into something competitive takes some doing.

 

[graydog8josh]

Neil? Where are all the official rules and details to the competition posted? I would like information to the classes that compete and how they are split up. I would be interested in building a hi powered motorized bicycle out of a non kit engine and a Racing 2 stroke or 4 stroke china, but i am not too clear how the class divisions are split up. Were driving out to michigan next week(formula sae) and im meeting with a big supporter of my push for motorized bicycle business for the university, im trying to get some details together for a proposal for a trip.

 

[MotorBicycleRacing]

Neil? Where are all the official rules and details to the competition posted? I would like information to the classes that compete and how they are split up. I would be interested in building a hi powered motorized bicycle out of a non kit engine and a Racing 2 stroke or 4 stroke china, but i am not too clear how the class divisions are.

I only have my phone so can't post much until l get back to my computer.
The classes and rules are supposed to be on the first page of every race date thread but that didn't happen for the April 13th race.

Did you see the April race results?
Those were the classes.
What non kit high powered engine are you considering?
Motorcycle engines that have manual shifters are not allowed.
11.99 hp is the top race class with anything over that being in the Unlimited Class.
I have been meaning to lay it all out in a June 1st race thread.

I got another question today by PM asking about using sick bike parts shift kits in the race classes. They have always been allowed in any of the classes.
Sick Bike Parts have sponsored SoCal Motor Bicycle Racing events with great prizes including both their 2 and 4 stroke shift kits along with their other accesssories!

Sent from my SCH-R720 using Forum Runner

 

[graydog8josh]

how long is the course?

 

[MotorBicycleRacing]

how long is the course?

All That info is on the 1st page of every race thread.
Click on the June 1st link in my signature!

Sent from my SCH-R720 using Forum Runner

 

[graydog8josh]

MotorBicycleRacing
Motorized Bicycle Elite Member

Join Date: Jul 2010
Location: SoCal, OC
Posts: 3,190
Thanks: 91
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Sat OCT 20th 2012 @ Grange Motor Circuit SOCAL MOTOR BICYCLE RACING
Grange Motor Circuit SOCAL MOTOR BICYCLE RACING




NEXT SoCal Motor Bicycle Racing Sat June 1st 2013

Gate opens at 6.00am Saturday for registration;
Sign waiver, get a wrist band and to pay entry fee.

Spectators / Pit Crew: $10
Kids 12 and under no charge.
Race track riding & Racing: $35
2nd Race Class: $10
3rd Race Class: no charge.

Practice from 7am to 9.45am
Heats start at 10.15am

Free camping Friday night and Saturday night included with track entry or
as a spectator.

Grangé Motor Circuit GrangeRaceTrack.com
20455 Central Rd.
Apple Valley, CA 92307

Track Specifications: 3400' elevation.

14 turns
8/10 mile
950' straight away
Elevation Changes
25' to 30' wide asphalt
Concrete Curbs on inside turn radius
Concrete Rumple Strips at run-off areas
25' minimum run off

We are running the track Counter Clockwise

 

[graydog8josh]

So i finally have gotten a bike i think could possibly keep up wiht the pack.
I have been getting up to the lower 40's pretty consistantly riding through town every day.
I have some sprocket alignment issues and have been scrounging around to get some shorter sturdier bolts for the old rag joint.

Right now im using my diamondback frame with a 1" threaded suspension fork(a cheap one) I have front v brakes with koolstop salmon pads. 26"x 2.4 tire cst cyclops tire on the front aired up to 55psi, 26" 1.95 kenda quick trax tire on the back aired up to 55 psi.
ive got a cloud 9 seat slammed down so i can get low, but i kinda think i need to get lower, ive been known to play around with different tire sizes to get my body lower, i think i might try running a 24" tire in the back with the cst cyclops fatter tire in the back and a 34t sprocket.


36t sprocket

ive got a 2 liter tank and im running 93 octane ethanol free with 32:1 mix

my engine is :
fred head stage 2 6.0cc
modified fred piston
ported stage 2 fred cylinder
dax f80 gen iv engine
21mm phbg clone carb w 76 jet
snake racing pipe(da best)
bpr7hix plug

So im reopening this thread for suggestions as i am planning on taking vacation time to go out to the races in october if they have them.
Also have gained some weight since last posting and want to get myself back down to about 170 for the races too to maximize my experience on the bike.

some things im thinking about fixing on the bike before racing it are:
Get the seat position lower
shorter rear tire(20" if i can find a 2.4 20" ) i think that would work pretty good
shorter front tire i will get a 24" front tire and put a disk brake and triple tree fork. i dont know how that will handle, but i want to get the bike stanced better.
Maybe a custom tank, if i can get all the weight of the bike centered better, i tend to rest my knee on the tank how it is.
better mounting of the exhaust pipe.