weed eater bike questions

deacon · Apr 5, 2008

No not the bike that runs off into the field, but the bike that is made from a weed eater type engine. I know this is going to be a high guest read thread because it is so hard to find any information on them. I have looked and it really is a jump all over the net for bits and pieces of information.

So I decided to start this thread and see who shows up.

First question is, okay I have a couple of weed eater engines on the way. The one i bought on ebay I found out has finally been shipped today. One of the members here has kindly sent me an old weed eater of his that matches my motor to fix or use for parts. Thank you again Joe.

Now here is my FIRST QUESTION

I know the engine had a square hole in the drive shaft to receive the flex cable from the weed eater cutting head. Now what exactly holds the end of the cable securely to the engine.

I think I have the design for the mount pretty much in my head, it is the same as for the electric motors more or less. It's just how to attach the drive wheel that has me wondering.

Big Joe · Apr 5, 2008

Deacon
There is a screw that holds the shaft (hollow tube the cable is in) into the housing of the clutch. These tubes are apprx 2 ft in length. (too long for box engine is in) I will save these until you are sure you do not need them.

deacon · Apr 5, 2008

Okay but I'm sure I can rig something. I have seen the drive wheel mounted right up on the end of the engine. The centrifical clutch was still there so somehow the bolted the wheel to the clutch. I'mn just gonna have to see it to know how to work it. thanks for saving it. I might need you to tell me what it looks like later when i start attaching the drive wheel.

deacon · Apr 6, 2008

Ive been chewing this over and here is the mount I designed

it is a flat mending strip attached to the bike, then a strap gate henge attached to that on one side, then an "L" bracket as a lift handle.

http://i25.tinypic.com/hun1c1.jpg. I might have to add a platform onto the henge to hold the motor.

I think it has a square box on the end of the clutch. I can imagine fitting a nut in there and drilling a hole through the housing and the nut for a pin. then having three nuts welded together to make a holder for the drive wheel.

A simple screen door type spring to keep the tension on the tire.

That should do it. At least I think so. With a little luck it will be the ultimate simple inexpensive motor bike.

elegant in it's simplicity...

Bikeguy Joe · Apr 6, 2008

Ace hardware has a massive spring collection/assortment if there is one near you.

deacon · Apr 7, 2008

Good to know I am going to need some small ones for the throttle return Im sure.

deacon · Apr 7, 2008

Engine arrived from the ebay dealer, now I need to know which way a ryobi 31cc engine turns when it is running... If I am looking at the fly wheel does it turn clockwise or counter clockwise when it is runing. I have a feeling it is counter clockwise but im not at all sure.

It seems it should run counter clockwise but that is just a guess based on lawn mowers I have had.

Big Joe · Apr 7, 2008

Deacon. The engine I shipped has the rope still attached. Just pull the rope and look at the cable housing (you can see it) Or just stick the cable in the hole and pull rope.

deacon · Apr 7, 2008

I got the one from ebay to start. I don't have a gas tank hooked up yet so I couldn't keep it running but it ran on the gas i poured down the spark plug hole. It is going to be an easy build I think.

There are threads on the Ryobi drive shaft. the are 3/8 inch 32 threads. If I am not terribly mistaken the foot pegs on some trick bikes have a 3/8 32 female opening. It should just screw on. The only problem I see is the threads require a clockwise turn and the engine turns counter clockwise. Sounds like a job for lock tight or jb weld on the threads of the peg.

I have decided to run a cable from a brake handle to the bracket to lift the engine off the tire from the handlebars. If that works this will be one sweet build. Of course it wont lol.

deacon · Apr 7, 2008

Now I need advice. I have the motor started once.. so I'm good there for now... I had my neighbor weld the bracket so I'm good there. I can't mount things till My new wheels get here but,, I need some advice...

The bracket is a large henged L ... So now how do I attach the engine (had no mounting holes since it was hand held as a trimmer...

I'm thinking to get it set as flat as possible... shim it in place then put a band of some kind to hold it. Maybe a cable with a spring for tension to hold it flat on the frame. I am open to a better idea...

Ilikeabikea · Apr 7, 2008

Deacon are there any substantial bolts you could take out and put some kind of strap under the head of the nuts or bolts????????????

deacon · Apr 7, 2008

Nothing at all. I'll send a picture of it so you can see what I'm dealing with. The gas tank is missing from this one so I can't even run a strap around it all I have a big void in the middle I have to shim up. Then I have to run new gas lines to a tank I have. I'm going to put it behind the seat somehow.

deacon · Apr 7, 2008

This is where I am right now with it. Im thinking strap or cable from the vertical post on the right to the platform under the motor. Tie it to the vertical post. Shouldn't be too much pressure since it will be laying against the tire. any suggesting would be appreciated.

Ps dont ask about the orange paint lol.

deacon · Apr 8, 2008

I think hose clamp around the heat fins and the jug connector area will do it.

deacon · Apr 8, 2008

Here are a couple if answers for you.

the ryobi 31cc weedwacker engine has a threaded shaft. The threads are 3/8 x 24 there is a bmx type axle foot peg that fits it perfectly. Makes a great drive wheel. It is already knurled as well. I bought a pyramid at the bike shop that has both 26 and 24 threaded ends. The 26 thread is a non cruiser type bike. The 24 is for cruiser bikes.

So here is where it stands. I have the engine started once with pour in the plug gas. Haven't tried the carb yet since I don't have the engine or the gas tank mounted. I'm waiting for the new wheel I bought to arrive.

I bought a big big push button kill switch since I am not going to bother with a lift cable after all. I think the kill and restart will work just as well. I have seen guys on u tube start them with a single turn of the wheel. I'll be able to hand start it to warm it up, then drag start it from then on. Might take a little getting used to but it should work just fine.

Norman · Apr 8, 2008

Deacon
to mount that engine take off the flywheel and under it is the cooling shroud and 4 bolts throw the cooling shroud and use the 4 bolts to make your mount
I have the same engine and I stopped cause the carb needs a kit and I'm too cheap to buy one the engine is new and the carb dried out and the diphram is stiff. I had it mounted on the recumbent. I started out with a 7/8 shaft and that was too small in dia. I think about 1" or 1 1/4" might be the way to go but I lost interest in my build so its rusting on the back porch.
Norman

deacon · Apr 9, 2008

Norman said:
Deacon
to mount that engine take off the flywheel and under it is the cooling shroud and 4 bolts throw the cooling shroud and use the 4 bolts to make your mount
I have the same engine and I stopped cause the carb needs a kit and I'm too cheap to buy one the engine is new and the carb dried out and the diphram is stiff. I had it mounted on the recumbent. I started out with a 7/8 shaft and that was too small in dia. I think about 1" or 1 1/4" might be the way to go but I lost interest in my build so its rusting on the back porch.
Norman

I know about the cooling shroud but I need the thing to hold the pull starter. I want to pull start it to warm it up then use the kill switch and drag start to run it up and down the road. I put a four inch hose clamp on to hold it to the mount. Went across the butt connection. This thing has no head lol.

Also I plan to use a door spring all the way across the engine, to hold it in place a little as well as keep it in contact with the wheel.

I found that a bmx axle peg works perfect to screw onto the shaft. If it is too small, I'm going to co with an engine mount rubber block Somehow I'll make it work. From the ones on u tube the peg should be fast enough for me.

Dave31 · Jul 20, 2008

Does anybody know what these little white arms are for? They swing to one side with the centrifugal force.

deacon · Jul 20, 2008

Now this is just a guess and I have no idea if it is right or not but, I had two 31cc engines recently. One with and one without centrifugal clutch. I think t they are part of that system. I think when the engine spins with enough force to spread them out they make contact with the clutch housing and cause it to turn, or they are part of the rope/spring starter system. It has to be one or the other for sure.

Dave31 · Jul 20, 2008

You are right Deacon, I just took a second look and they are for the pull start.
Thank You

weed eater bike questions

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