Extra muffler silencer

Well, that's one way of doing it!  I honestly don't think the stock engines are really that loud, but if you really need to make her quieter, this is another(albeit ugly) way!

BGF engine teardown

Things are kind of slow for now, so if you aren't a regular on MB boards, I thought I'd share an active thread.


Biknut from motorbicycling.com is tired of poorly built HT engines, so he's tearing down a new Boygofast engine to ensure that it's properly put together.  Read more to watch him tear apart an HT!

UPDATE: Unfortunately, it seems that many of the images from the original thread are gone.  It still may prove useful to read, and pictured above is biknut's ingenious way of pressing the crank out of the engine.

Cleaning up your electrical

If you have come across other pictures of my bike, you'd have seen my electric wires hanging out and simply clamped to the bike with zip ties.  These 2-stroke kits pretty much just have the electrical connections hanging out and I really hate that.  Also, I chose to zip-tie my CDI instead of using bolts(since it's plastic and apparently breaks easily), but that caused the CDI to move around and the plug wire would often be hanging out the side. 

Well recently, some guy was tailgating me and I made a sharp right turn and, well, I wiped out.  Got some road rash, but at least I got the opportunity to revise my set up!  I wanted something both visually and practically superior, so this is what I came up with:

• I moved my CDI to the top bar on my frame.  That way it won't slide much even if you zip-tie it.  For some reason I just think it reduces clutter that way instead of having all the wires smashed up on the one bar on the bottom.
• Shrink tubing: People say to solder the wires and use electrical tape.  I decided to go with something nicer looking and less sticky.  You can get shrink tubing at Radio Shack or anywhere that sells electronics supplies.  Just cut a piece, slide it over the bare area on the wire and roll a soldering iron over it to make the tubing shrink.  A heat gun may work well too.  It looks great and creates a nice seal to prevent shortage.
• I took all the wires, including the ones coming from the kill switch, and ran them through a piece of flexible cable tube that I cut out.  This looks MUCH better than having all the wires visibly hanging out.  You can buy cable tubing from Radio Shack or Wal-Mart.  Then I just zip-tied the tube to the bottom frame. 
• Used silicone sealant on the CDI(where the plug wire comes out) and where the magneto wires come out of the motor.  This in combination with the shrink tubing and cable tube should make this setup really water resistant.

P.S. Yes, I know that some paint is missing on my bike.  That's due to B-12 Chemtool and the fact that I spray-painted my frame.  One of the next things I plan on doing is patching those areas.


This post is sponsored by B-12 Chemtool: The world's most powerful paint-thinner!

DIY bike repair stand

Doing work on your MB can be troublesome without the use of a stand.  For some reason bike repair stands can be expensive, so why not build your own from hardware store parts?  Geoldr from motorbicycling.com was able to build one with some pipe from Home Depot for $65, although I imagine you could achieve something functionally similar for cheaper using a combo of PVC and construction re-bar.

A more innovative bike lock

Cable locks and U locks are great but are a bit troublesome to use.  It always takes me a minute to wrap my cable lock around my bike frame.  Wouldn't it be great to have a system that was lock-n-go?


Apparently you can get what's called a "ring lock" for your bicycle.  It securely bolts on to the frame, and all you have to do to lock your bike is turn the key!  It does this by locking through your spokes.  No fiddling around.  I imagine this would be great if you live in a low-crime area or if you just want to park your bike and run into a store(and not have some junior high school student ride away with it).  Still keep a cable or U lock for longer term parking, but I like the added peace of mind!


Velo ORANGE sells their own bicycle ring locks for $25 each! 

Soda can head gasket

Sorry, I don't have any actual photos because the camera I used got jacked up and the photos were lost. :(

You don't need to spend money to replace your head gasket!  If the one you have is in mostly okay shape, you can cut your own from an aluminum soda can!

Simply cut a large piece of metal off a soda can.  Notice how it still retains the shape of the can?  There's an easy way to flatten out the metal; take a clothes iron and iron it as flat as you can.  It won't be completely flat, but you can get it flat enough to be useable.

If this doesn't make sense, the first part of this video shows how this is done.

Once you have made a nice piece of flat aluminum, trace your old head gasket on it with a permanent marker.  Then simply cut out your new gasket with a razor blade or an exacto knife.  Most of it is simple to cut, but the stud holes can be difficult; the key is to try cutting them a little larger than you'd think you'd need.

When you have placed your new head gasket on your engine and placed the head back on, push your bike forward with the clutch engaged to make the piston move.  If there are any air leaks, you should hear(and feel) the air come out around part of the head.  This is very important to check for because air leaks are very bad for your engine.  The first soda can gasket I made had too much cut off from the center and that's where an air leak came from.  I did a better job on my second soda can gasket, and so far there are no leaks.  If you want, you can use Copper Kote to create a better seal.

Are there any advantages to a soda can head gasket?  Other than costing virtually nothing, soda can metal is much thinner than the stock head gaskets, so if you're looking for both a quick fix and less compression, a soda can head gasket might be the way to go.

$5 solid tensioner mount

There are plenty of tensioner mods involving a spring, but sometimes people have issues with a spring-loaded setup.


This mod will give you a tensioner that is both solidly mounted and one that definitely won't fall into the spokes!

Motor-mounted chain tensioner

This is a different kind of spring-loaded tensioner I came across, so I thought I'd share it since it's an interesting option.  Most of the time, the tensioners are attached to the bike frame, but instead this one appears to be mounted on the motor.  Not sure how much more convenient it is, but it looks nicer and maybe if you're going to move a motor to another frame it'll help there too.

Backwards cylinder jug

Isn't it strange how the stock engines have the intake on the rear and the exhaust in the front?  Of course the reason for this is to make these kits easy to install on most bikes.  But if you want a more logical approach to running your engine, it is possible to turn around your cyclinder jug so that the exhaust is in the rear and your carburetor in the front.  If you're looking to increase intake flow and to get the smelly exhaust behind you, then this might be a good mod for you.


Before you go spinning your jug around, please keep in mind that you have to do a few more changes in order to make your engine run properly with this setup.  Read more to learn what to do!

Candlestick velocity stack

A velocity stack eases the flow of air into the carburetor.  Wikipedia says that a velocity stack for an engine does two things:

1. Allow smooth and even entry of air at high velocities into the intake tract with the flow stream adhering to the pipe walls.
2. Modify the dynamic tuning range of the intake tract by functioning as a resonating pipe which can adjust the frequency of pressure pulses, based on its length, within the tract.

In other words, it works like this:

Instead of permanently polishing out the NT carb intake like others done, you can get a similar effect by having a velocity stack.  Bairdco made one out of a candle holder from a swap meet.

Piston skirt trimming

Sometimes, with the way these little engines are put together, the piston doesn't completely clear the intake port.  This means reduced flow.  How can this be solved?  By simply trimming the piston skirt to clear the intake!  If you're looking for a little extra power increase, this might be a good answer(if you're careful not to trim off too much that is).  HeadSmess on motoredbikes.com shows how this is done, along with a few other changes like widening the ports.

"Brake noodles" for better clutch/throttle cable clearance

Sometimes, depending on your set-up, it's hard to get proper clearance with your clutch or throttle cable.  A brake noodle might solve that problem.


Bairdco attached a brake noodle to his clutch cable so that it clears his rear exhaust.  You can get brake noodles at a local bike shop, or you might be able to get one off of an old brake system. 


Using a brake noodle may also make the clutch easier to operate, similarly to how the clutch pulley works.

Aftermarket high-compression head

The more compression, the more power!  You can do things like replace your stock head gasket with a thinner one, but you can also do something extra for your compression by buying an aftermarket high-compression head!


Pirate Cycles sells these high-compression heads, and they're high-quality parts made in America! 

EDIT: Some engine/kit distributors seem to now be offering similar products.  Yay!

Awesome MB trailer

This MB'er made an awesome storage trailer for his motorized bicycle!  He used a Burley Tailwagon as a base, and this project looks very professional.  Would be a great way to use your MB to take a trip somewhere!  


Though I noticed this trailer uses two wheels.  I am not sure about the legality, but I think in some states your bicycle can only be street legal if it has 3 or fewer wheels.  But I've seen bike trailers with only 1 wheel, so perhaps something similar could be built in that fashion.

Copper pipe fuel tank

Large copper pipe might be more expensive than PVC, but when soldered together, it makes a sick and solid fuel tank! 

PVC fuel tank

I love projects that can be made mainly with hardware store parts.  If you're looking for an easy, affordable, and practical replacement for the crappy stock fuel tank, you can simply use PVC!

Ferball on motorbicycling.com came up with a fuel tank made of PVC pipe and two end caps.  I was skeptical at first(since PVC on its own is kinda ugly), but the end product looks great!

UPDATE: If building a PVC fuel tank, I'd recommend applying a proper fuel tank sealer.  Some people have claimed success with PVC, but gasoline is known to cause PVC to deteriorate over time.  To be on the safe side, use something like Kreem Fuel Tank Liner.

DIY $15 silencer muffler

I've never been a fan of the stock mufflers, but I really like unique setups like this!  Sure, it doesn't have the "chopper" look, but there already so many chopper bikes out there.  And I think it's great finding ways to reduce noise and maintain performance.

Duke.55 on motoredbikes.com came up with a homemade silencer muffler made from some gas and water fittings, a tin can, and some steel wool!

Homemade magneto

Impression is trying to figure out how to build his own magneto!  Magnetos are a pretty simple concept, so I think this should be possible!


Join the conversation about building a homemade magneto at motorbicycling.com.

12 volt engine generator for lighting

The white wire that comes off our HT motors can power some lights, but if you did that you'd be taking away electrical power from the spark plug.

This modification possibly solves that problem.  Now you can power your lights from your engine and keep your spark power!  From the looks of it, it's a smaller separate magneto coil.  That way you're getting power separately and not taking it away from the main magneto coil.


If you don't want to build one of these yourself(I don't even know how), you can buy the the entire system on eBay!  Ebay user mightywonderful is selling the Mini-Gen Max, which is a complete separate power system for your motorized bicycle.