First Time Bike Builder

DreamRyder1963

DreamRyder1963

New Member
This is going to be my first motorized bike build. I am looking primary for a toy. This is more for the fun of the build and novelity of the finished product. Reliabilty is not a huge extreme for this build the most I will be riding is probably around my nighborhood. I on a very tight budget and parts will either be fabircated or salvage from other projects. I have an engine from kids motorized bike toy that had a broken frame. The frame is a simple mountain bike. I am looking for advice on what type of problems are common with a build like this, other parts I may have over looked, etc. I will post a pic of the engine and frame. Thanks for your help.
 

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DreamRyder1963 said:
This is going to be my first motorized bike build. I am looking primary for a toy. This is more for the fun of the build and novelity of the finished product. Reliabilty is not a huge extreme for this build the most I will be riding is probably around my nighborhood. I on a very tight budget and parts will either be fabircated or salvage from other projects. I have an engine from kids motorized bike toy that had a broken frame. The frame is a simple mountain bike. I am looking for advice on what type of problems are common with a build like this, other parts I may have over looked, etc. I will post a pic of the engine and frame. Thanks for your help.
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Welcome to the forum, all but 1 bike I built was to be used as a toy "fun". My first was for my son as he didn't have a drivers license but we straightened that out (lost for 14 years). For those that this will be your first build, I have compiled a list of things that “I” do before installing a Chinese HT engine on a bike frame. Some are needed and other will help with the longevity of the engine itself. Happy riding, and be safe.
https://docs.google.com/document/d/1...QUZq2qXXE/edit
 
Thanks for the tips. I'm wondering if I need a fuel pump for this type of engine. Especially if the tank is mount higher than the carburator.
 
DreamRyder1963 said:
Thanks for the tips. I'm wondering if I need a fuel pump for this type of engine. Especially if the tank is mount higher than the carburator.
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On these Chinese HT engines, the carburetor is fed by gravity. It takes such little fuel flow to keep up with what is burned, even at WOT.
 
That's good news. That has been a flaw in my design. The bike I took this off of didn't have a clutch as far as I could tell. Does this engine have one built in?
 
DreamRyder1963 said:
That's good news. That has been a flaw in my design. The bike I took this off of didn't have a clutch as far as I could tell. Does this engine have one built in?
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One with a STANDARD clutch (has a clutch arm mounted on the handlebar) will look like this... What you are looking at is the clutch pads under the cover (behind the flywheel) on the right side. And has a arm like the one pictured just below the intake studs, in the first photo.
....

Check out this album....
http://s982.photobucket.com/albums/ae309/Ron-Becker/Chinese HT breakdown/?start=all
 
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Welcome, DreamRyder1963,

Your toy engine is a 43cc Mitsubishi-clone engine w/about 2hp and electric start. You SHOULD have a centrifugal clutch, maybe even a 5:1 gearbox. You should already have a saddle gas tank on your engine. That'll be good for riding at least 10 miles.

Thatsdax.com has a rear-mount ed friction drive assembly. If you DO have a gearbox attached, remove it. Then your engine will bolt directly onto it. It's the easiest drive assembly available. You should be riding around the neighborhood in a few hours.

The only extra equipment besides the engine drive kit you'll need to buy is a rear tire with flat, not mountain-bike tread.

You'll be pleasantly surprised how fast your motorized bike will run, at least 32mph with 1.5" friction roller. With a smaller-diameter roller, you'll have more low end power. Personally, I like the 1.5" roller. It might have less low end, but MUCH more than a pedal bike anyway.

Good luck and have fun.dance1
 
I posted thinking you had a Chinese engine, as the pictures didn't load up before my first post, now that they loaded (why I don't know) disregard my posts.
 
DreamRyder1963 said:
So if there is already a gear box attached, why would I need a new one. Is any of the previous info correct
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DreamRyder1963 said:
So if there is already a gear box attached, why would I need a new one. Is any of the previous info correct
Click to expand...

If you DO have the 5:1 gearbox already on the engine, you COULD use Thatsdax's rear-mounted chain drive assembly. It's a little more involved, because you have to install a sprocket onto the rear wheel.

If you have an 8mm 22t sprocket on your gearbox, then order Dax's 72t rear wheel sprocket. It's drilled to bolt directly on your rear wheel spokes with their adaptor. That'll give you a 16.36:1 gear ratio, which is pretty good for road use.

If you want more low end and slower speed, you can install a 17t on your gearbox. This will give you 21.18:1 and excellent low end power.

If you want it easy, remove the gearbox's 4 mounting bolts. The gearbox will fall away. Then the friction drive bolts right on. On wet tires, you'll have slipping problems.

With Dax's chain drive, it's a little more involved but more dependable. No problems with wet tire.

Oh yeah, you'll need the battery for electric start. If you have an optional pull start, just use that.

Good luck. It sounds exciting!dance1
 
It has a pull start and magneto. My biggest thing is price I am basically trying to build this just on free parts, mainly as a challenge.
 
DreamRyder1963 said:
It has a pull start and magneto. My biggest thing is price I am basically trying to build this just on free parts, mainly as a challenge.
Click to expand...

For a cheap install, just buy the 72t rear wheel and 8mm chain. Then make your own motor mount.

You will be VERY surprised how fast this engine will make your bike go.dance1
 
Sorry, my bad. "t" stands for teeth. A 72t sprocket has 72 teeth.
BTW, your gearbox either has a sprocket for #25 chain(tiny) or 8mm chain(larger, boxier).

The Dax 72t sprocket is for 8mm chain. If yours has #25 chain, simply replace the gearbox sprocket to 8mm sprocket.
 
DreamRyder1963 said:
Ok that makes more sense. How simple r the gears to swap? Sorry I'm not near the engine right now.
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The sprocket on the gearbox's shaft is held on by a 40-cent snapring/circlip. Buy two spares and keep one in the new toolbag you'll be carrying on the bike. The snapring plier is inexpensive and easy to use. You can hold your breath longer than it takes you to remove or reinstall the sprocket and circlip.

If you use the 11t sprocket, keep an eye on the circlip during maintenance. The chain runs VERY close to it. In a few months, the chain will grind the circlip down to a neat fishook.

Ask me twice how I know this.

After you remove the sprocket, it is a good time to split the gearbox in half, clean it and fill it with grease. Then reassemble with gasket sealer. The gears inside the box are tiny and noisy, but the box is VERY dependable/reliable.
 
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