My First Motorbike Project

gera229 · Oct 8, 2011

Oil, sprocket, and gearbox came in.

For anyone interested on how this reduction works I attached a picture. I opened up the gearbox an found chain driven gears.

The Drive sprocket (front) that the clutch spins is 9 teeth and the driven sprocket that spins the outer sprocket is 27 teeth.

27/9 gives a 3:1 ratio meaning 3 spins at the drive sprocket gives one spin at the driven sprocket.

lowracer · Oct 8, 2011

Gera,
The spark plug wires that comes on the Stage 2 kit is cheapo Chinese junk. Go to your local auto parts store & pick up a double ended 'L' boot spark plug wire for ~$5.00 & cut it in the center of the wire (so you'll have 2 complete wire/boots for 2 engines).
I do have 2 triangle ports on my piston (saw them after blowing up that one engine).
-Lowracer-

gera229 · Oct 10, 2011

Hey lowracer when I calculated your gearing ratio I calculated it wrong.

22.25/1.5 = 14.83.
and
22.25/1.43 = 15.56

Now if I use a 14T sprocket then my ratio will be:
(72/14) x 3 = 15.43
Pretty similar to yours.

Your acceleration seems decent and maybe even good for a bike compared to the China girl 66cc/ 69cc engines, so I will keep that ratio. I will try 11T to experiment, but I will probably keep this ratio as my main ratio to use.

lowracer · Oct 10, 2011

Gera,
Get yourself a Full Suspension bike.
I've built 3 MB's now, & the only one I wanna ride is the full suspension DH bike.
Trust me on this one...
-Lowracer-

gera229 · Oct 10, 2011

I need a bike with inner frame space because I'm mounting the engine inframe.
I will see what the store has that fits within my budget.

And yes, of course I should get a full suspension bike, but then again I won't be going that fast constantly.

Thanks.

gera229 · Oct 13, 2011

lowracer said:
Gera,
In the 2nd picture, you got it all backwards. The hole you have the barrell sticking out isn't used.
These exhausts only fit the pocketbikes they were designed to fit.
We as bicycle builders need to cut & either weld or clamp sleeves onto the pipes to fit our intended purpose. I use some nice flex pipe I bought online to connect the exhaust header to the cut down exhaust pipe. I then use some ceiling fan drop pipe to connect & clamp the connections (I dont weld).
-Lowracer-

Would you mind tell me how you did yours with pictures of your carb and pipe?

gera229 · Oct 13, 2011

The rest of my stuff came today and I can say I am disappointed with the exhaust because it does not fit due to the gearbox in the way.

gera229 · Oct 13, 2011

.............

lowracer · Oct 13, 2011

Gera,
I posted alot of pics & info of my builds on my threads & I'm sure you can see how I did it.
Everyone does it differently & every bike is different. For me, most of the fun of this hobby is figuring out how to do it myself. Some nights I wake up thinking how I need to accomplish a task that was on my mind & do some of my best thinking in those wee hours of the night. I get ideas from others on these forums, but I still do it my way. You'll figure it out...& if you cant, you should have bought a kit.
-Lowracer-

gera229 · Oct 13, 2011

I WILL figure it out. Whenever someone tells me an idea, it always leads me to think I should do it exactly like them lol. I would rather spend time learning than buying a kit.

By the way, how much did you spend on your motor and parts all together, accessories, spark plug (and all the other replacements including the mcmaster bolts and plug wire), fuel tank, etc?

I total out at 390 dollars all together including engine, every replacement, gearbox, chain, sprockets, mirror, handle and throttle set, spark plug, aluminum 1/4" thick sheet for bolting the engine on it, and all the rest.

lowracer · Oct 14, 2011

Gera,
Here is a pic I took today to show you the cable in the slide.
I think a pic is worth a thousand words.
I have no clue how much I spent on my rigs. I have 3 MB's & a total of 9 bikes in the garage.
I probably would rather not try to figure out how much I got invested (alot!)
-Lowracer-

gera229 · Oct 14, 2011

Haha ok makes sense. You the the barrel is it sitting upwards (vertically) or is it sitting sideways (horizontally) cuz I can't see in the picture.

Thanks.

lowracer · Oct 14, 2011

Vertical, see the cable?

MRJOHN · Oct 14, 2011

gera229 said:
Update: I just realized that the inframe kit with chain drive will just not work. The motor has to be in the rear because for the inframe to work you need to turn the motor upside down due to the direction in which it spins and I do not think that will be good for the motor.

If you know anyone who did an inframe kit I will be glad to know.

i have the 54 CC 2 Stroke Engine (Big Bore Stage 3

gera229 · Oct 14, 2011

Hey @MRjohn I am glad you have one now I can have 2 people helping me. To is better than 1

.
What size in length is your pocket bike chain? I hope 44 inches is enough and that was the largest I could find.
What sprocket sizes do you have?
How many miles are on your engine? Is it stronger than your China Girl engine?
Your gearbox seems to have a 3:1 reduction, correct me if I am wrong.

@Lowracer
It looks horizontal. The cable looks like it's bent at an angle there.

By the way Lowracer, I bought a spark plug that came without a pack, how can I verify that it is not made in China? When I look inside the spark plug head inside of it, it looks like a clip on instead of the Chinese coil type. Is that how yours looks?
I got my spark plug from autozone (I hope they do not sell generic wires because then I would be sure that I got a high quality one.). 7mm thickness.
Red in color double headed wire. One of the heads seems to be shorter in length than the other head, is that the same for you?
I think if it is then we have the same spark plugs, just different colors.

I shaved my wire off to have it fit and got to the yellow colored layer which would fit. Do you have this white colored layer on your spark plug? Or at least another layer? If so then we sure do have the same plug wires, but different colors.

How do I check if the spark plug sparks? Cuz I turned the flywheel with my hand trying to do it fast at a time, but I saw no spark. Then tried it with the original Chinese wire, still no spark.
Thanks.

gera229 · Oct 15, 2011

Here is a picture of my wire.
I looked at the picture of your wire and circled the difference. As you can see on the head I have those little things that I circled, but you don't.
But I doubt that would be considered a major difference? Do you think we have the same spark plug wires?
You wire pictures are here:
http://motorbicycling.com/f4/pocket-bike-engine-project-31377-11.html

Sorry for the long previous post, I hope you read it all.

lowracer · Oct 15, 2011

Gera,
You need to buy a bike, hook up the fuel tank & drivetrain & start the thing to check for spark (engine will or wont run). Dont try starting it unmounted!
I didnt remove my silicone spark plug wire coating down to inner cable like you did. I just shaved some outer silicone off until it fit, then screwed it onto the post & used black electrical tape to keep it all secure. Spark plugs come w/ either threads on top or a screw-on metal top over the threads. My plug wires fit the screw-on metal top so I had to remove the one from my old spark plug using a vice-grip & thread it down onto my new spark plug. Buy NGK spark plugs....they are the best IMO. Both my spark plug heads were the same (7mm black wire).
-Lowracer-

gera229 · Oct 15, 2011

Low racer, does your second layer inside also look yellow in color? I had A LOT of spare NGK C7HSA I found in my garage and using that.
Just hoping we have the same quality spark pugs lol.

And my plug wires fit the screw on metal top too, inside the plug head it like clips right on it (Not the coil version type like the Chinese plugs have, its like round metal that clips on), is that how it is for you?

I'll show a picture of spark plug heads.

Thanks.

gera229 · Oct 15, 2011

Here are the pics of what I am talking about.

When I look at your picture I see one of your heads is also like that, but I cannot tell for sure unless you verify by checking them.

I know this is not important lol, just checking if we have the same wires since we both got them from auto zone.

Also did your wire come in a package or did it come unpackaged/ unwrapped?

MRJOHN · Oct 15, 2011

gera229 said:
Hey @MRjohn I am glad you have one now I can have 2 people helping me. To is better than 1 .
What size in length is your pocket bike chain? I hope 44 inches is enough and that was the largest I could find.
What sprocket sizes do you have?
How many miles are on your engine? Is it stronger than your China Girl engine?
Your gearbox seems to have a 3:1 reduction, correct me if I am wrong.

@Lowracer
It looks horizontal. The cable looks like it's bent at an angle there.

By the way Lowracer, I bought a spark plug that came without a pack, how can I verify that it is not made in China? When I look inside the spark plug head inside of it, it looks like a clip on instead of the Chinese coil type. Is that how yours looks?
I got my spark plug from autozone (I hope they do not sell generic wires because then I would be sure that I got a high quality one.). 7mm thickness.
Red in color double headed wire. One of the heads seems to be shorter in length than the other head, is that the same for you?
I think if it is then we have the same spark plugs, just different colors.

I shaved my wire off to have it fit and got to the yellow colored layer which would fit. Do you have this white colored layer on your spark plug? Or at least another layer? If so then we sure do have the same plug wires, but different colors.

How do I check if the spark plug sparks? Cuz I turned the flywheel with my hand trying to do it fast at a time, but I saw no spark. Then tried it with the original Chinese wire, still no spark.
Thanks.

i have a #41 Chain and a 10 tooth engine sprocket on the
gearbox,48T steel sprocket on the rear Wheels i may go down to a 36sprocket

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