HOW I MAKE A FRONT MOUNT
1. Preparing the front fork:
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The first thing I do is to attach a piece of angle iron to the front fork. This piece is to give me an attachment point for my henge. I make it about five inches long with a hole drilled dead center of the angle iron. I run a 1/4 bolt all the that hole and the brake holder hole in the front fork.
Next I need to get the angle iron square with the forks then drill one more 1/4 hole through one side of the fork. Just through the angle iron and one side of the fork tube. One of the big problems with mounts is that they slip and allow the engine to twist so that the roller is tilted on the tire. I want as much contact with the tire as possible. Thats why the second hole is necessary.
First I coat a short 1/4 bolt with super glue, then I slide that into that second hole. A couple of minutes later it will be set. There is no pull on the bolt, so is it really just a pin to prevent it twisting. I’m sure there are better ways to do it, this is just simple and seems to hold up okay.
2. Preparing the engine.
From the humble weed eater to the mighty Ilfan, engines seem to have a mounting around the drive shaft. It it doesn’t then this won’t help you much. The guys who have machine shop tools can do this ten times better than I can, but this seems to work okay.
The pattern is there are two holes on top with a space between them that doesn’t quite clear the fan blades on the weed whacker. On the larger motors the fans aren’t the issue stability is. The engines also have two more holes below the drive shaft.
You can reuse the small screws that you would have had to remove to get your weed eater to the point to mount, but I drilled and tapped my holes for a standard quarter inch bolt. I felt like it gave me a little more beef but I can’t prove that.
Anyway the top piece is an angle iron with two hole drilled in it to mount directly to the engine. the top piece should be a couple of inches longer on each side than the engine mount. What you want to do next is to run a reinforcement piece of metal from the bottom holes on the engine to holes you drill a couple of inches away from the two top mount holes. It makes a kind of stretched out W pattern. Now be sure to use washers on the bottom holes in the motor between the reinforcement piece and the motor frame to build it out, so that the engine isn’t tilted too much.
3. Building the mounting frame.
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Buy yourself a 4.5 inch steel hinge from Home Depot or Lowe’s. When you get home attach a one foot long piece of angle iron to each of the outside holes on one wing of the hinge. Then attach another piece of angle to the two loose end of the angle iron. At this point you have a rectangular box on which one end is a hinge.
What you want to do at this point is to bolt the motor’s top angle iron mount to the box you have just built. Remember to get it on the correct side depending on which way the motor rotates. A weed whacker mostly rotate counter clockwise so they would be on the left side if you are sitting on the bike. Once you have a couple of 3/8“ bolts holding the engine to the frame then take the whole thing to the bike.
Attach the unused wing of the henge to the mounting point you bolted to the front fork. Slide the hinge around until the roller on the engine is on the tire as you think it should be. Then mark the holes in the henge. Now drill the holes and bolt the engine on. If you did it all correctly the engine is square and the roller is flat on the tire at this point.
4. The comfortable scissor hinge. (so named for the lady who taught me how to use it)
take two pieces of flat bar stock. I use the stretcher bar from a chain link fence. It is a good width and thickness and best of all it is cheap at the home depot. When fitted to your fork and the right side of your motor frame, the two piece should form a hinge Double bolt them at all three points so that they will move but stay together. This simple hinge will keep the motor from sliding too much and guide it up and down. Even better it makes the foundation for the simple lift clutch.
5. Tension for the engine.
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The engine has to have tension on the tire to create the drive. Too much tension and you work the engine too hard and it won’t perform well. Too little and it will slide on the tire and doesn’t perform well. If the tension is right the engine will pull most of the time but it will slide on a steep hill so it doesn’t unduly stress the engine. With the small engine it is a helper you do have to pedal some. Larger engines this is not as much an issue. So I use a spring and a turnbuckle when I can to create tension yet still allow the engine to lift. That ability to lift is your clutch.
After all a clutch is no more than a disengagement of the drive chain. That is what lifting the engine does. HOWEVER since I spent a little time in the hospital and a lot of pain, suffering and money later. let me warn you. On an engine with high compression, do not lift it until you are almost at a stop, then do not reengage it at any speed other than a slow pedal. It will lock your rear end and trow you off the bike. the low compression weed eater isn’t a problem, the others are. I routinely drag start my weed eater but the high compression engine will throw the bike in a spin even doing that.
6. Building the lift clutch.
Building the lift on the front is different than building it on the rear. I build using the bmx type handle bars, but there is a way using any handle bars and I will explain that way. When you attach a brake cable to the bolt that holds the two ends of the comfortable hinge together, it becomes and easy way to open the henge and lift the motor. Use the brake lever and cable to change the geometry of the henge and lift the motor. You will probably have to tie the engine up to move it around the shop. You might engineer a way to keep the brake lever pulled when the engine is not in use. I ran a second cable to use to lock my engine in the up position
Building it on the REAR mount is a cable attached to the Comfortable hinge as well. When you pull on the cable the hinge opens lifting the engine. It is easy to use a brake lever to pull that cable and open the Comfortable hinge. Unfortunately it is almost impossible to lock the motor up this way. I like to drill a hold in the bike frame and make a lever for the lift so that I can lock it down. Then just flip it up to lower the engine.
Thats all there is to it.
Uploaded with ImageShack.us
Uploaded with ImageShack.us
1. Preparing the front fork:
Uploaded with ImageShack.us
The first thing I do is to attach a piece of angle iron to the front fork. This piece is to give me an attachment point for my henge. I make it about five inches long with a hole drilled dead center of the angle iron. I run a 1/4 bolt all the that hole and the brake holder hole in the front fork.
Next I need to get the angle iron square with the forks then drill one more 1/4 hole through one side of the fork. Just through the angle iron and one side of the fork tube. One of the big problems with mounts is that they slip and allow the engine to twist so that the roller is tilted on the tire. I want as much contact with the tire as possible. Thats why the second hole is necessary.
First I coat a short 1/4 bolt with super glue, then I slide that into that second hole. A couple of minutes later it will be set. There is no pull on the bolt, so is it really just a pin to prevent it twisting. I’m sure there are better ways to do it, this is just simple and seems to hold up okay.
2. Preparing the engine.
From the humble weed eater to the mighty Ilfan, engines seem to have a mounting around the drive shaft. It it doesn’t then this won’t help you much. The guys who have machine shop tools can do this ten times better than I can, but this seems to work okay.
The pattern is there are two holes on top with a space between them that doesn’t quite clear the fan blades on the weed whacker. On the larger motors the fans aren’t the issue stability is. The engines also have two more holes below the drive shaft.
You can reuse the small screws that you would have had to remove to get your weed eater to the point to mount, but I drilled and tapped my holes for a standard quarter inch bolt. I felt like it gave me a little more beef but I can’t prove that.
Anyway the top piece is an angle iron with two hole drilled in it to mount directly to the engine. the top piece should be a couple of inches longer on each side than the engine mount. What you want to do next is to run a reinforcement piece of metal from the bottom holes on the engine to holes you drill a couple of inches away from the two top mount holes. It makes a kind of stretched out W pattern. Now be sure to use washers on the bottom holes in the motor between the reinforcement piece and the motor frame to build it out, so that the engine isn’t tilted too much.
3. Building the mounting frame.
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Buy yourself a 4.5 inch steel hinge from Home Depot or Lowe’s. When you get home attach a one foot long piece of angle iron to each of the outside holes on one wing of the hinge. Then attach another piece of angle to the two loose end of the angle iron. At this point you have a rectangular box on which one end is a hinge.
What you want to do at this point is to bolt the motor’s top angle iron mount to the box you have just built. Remember to get it on the correct side depending on which way the motor rotates. A weed whacker mostly rotate counter clockwise so they would be on the left side if you are sitting on the bike. Once you have a couple of 3/8“ bolts holding the engine to the frame then take the whole thing to the bike.
Attach the unused wing of the henge to the mounting point you bolted to the front fork. Slide the hinge around until the roller on the engine is on the tire as you think it should be. Then mark the holes in the henge. Now drill the holes and bolt the engine on. If you did it all correctly the engine is square and the roller is flat on the tire at this point.
4. The comfortable scissor hinge. (so named for the lady who taught me how to use it)
take two pieces of flat bar stock. I use the stretcher bar from a chain link fence. It is a good width and thickness and best of all it is cheap at the home depot. When fitted to your fork and the right side of your motor frame, the two piece should form a hinge Double bolt them at all three points so that they will move but stay together. This simple hinge will keep the motor from sliding too much and guide it up and down. Even better it makes the foundation for the simple lift clutch.
5. Tension for the engine.
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The engine has to have tension on the tire to create the drive. Too much tension and you work the engine too hard and it won’t perform well. Too little and it will slide on the tire and doesn’t perform well. If the tension is right the engine will pull most of the time but it will slide on a steep hill so it doesn’t unduly stress the engine. With the small engine it is a helper you do have to pedal some. Larger engines this is not as much an issue. So I use a spring and a turnbuckle when I can to create tension yet still allow the engine to lift. That ability to lift is your clutch.
After all a clutch is no more than a disengagement of the drive chain. That is what lifting the engine does. HOWEVER since I spent a little time in the hospital and a lot of pain, suffering and money later. let me warn you. On an engine with high compression, do not lift it until you are almost at a stop, then do not reengage it at any speed other than a slow pedal. It will lock your rear end and trow you off the bike. the low compression weed eater isn’t a problem, the others are. I routinely drag start my weed eater but the high compression engine will throw the bike in a spin even doing that.
6. Building the lift clutch.
Building the lift on the front is different than building it on the rear. I build using the bmx type handle bars, but there is a way using any handle bars and I will explain that way. When you attach a brake cable to the bolt that holds the two ends of the comfortable hinge together, it becomes and easy way to open the henge and lift the motor. Use the brake lever and cable to change the geometry of the henge and lift the motor. You will probably have to tie the engine up to move it around the shop. You might engineer a way to keep the brake lever pulled when the engine is not in use. I ran a second cable to use to lock my engine in the up position
Building it on the REAR mount is a cable attached to the Comfortable hinge as well. When you pull on the cable the hinge opens lifting the engine. It is easy to use a brake lever to pull that cable and open the Comfortable hinge. Unfortunately it is almost impossible to lock the motor up this way. I like to drill a hold in the bike frame and make a lever for the lift so that I can lock it down. Then just flip it up to lower the engine.
Thats all there is to it.
Uploaded with ImageShack.us
Uploaded with ImageShack.us
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