Sprocket Alignment + other issues.

[Cr9ck]

My friend is helping me put my bike together and he has it at his shop right now. Its 80-90% done but we've run into some hiccups. He took the thing to his work today and said that the sprocket is off by 3/8 of an inch or so. The sprocket is mounted with the donuts on both sides. He thinks that he will need to grind them down to get the sprocket into alignment.

Also the idler pulley needs to be modified. Who knew it would be so much hassle to get this thing up and running. Heck putting on the rear sprocket took about an hour without having to align it. Oh yeah and the sprocket had to be machined to the wheel hub to get it to fit. Well at least alignment is perfect in that sense.

Has anyone else had similar problems???

Thanks

 

[Bikeguy Joe]

Can you turn the sprocket around, or will that make your alignment issue worse?

 

[Bikeguy Joe]

I've build five and had no problem (eventually) getting the chain run straight.

There are a few threads around here about the tensioner and what can be done.

 

[Cr9ck]

Hmm i think it would but I haven't looked at it closely. The donuts seemed a bit bent out of shape when i got them, uneven too. I was thinking about a bike chain though because a derailer keeps it straight at an angle. Do the 2 sprockets have to be in 100% alignment?

 

[Bikeguy Joe]

Pretty much.
A derailer chain won't work.

Sometimes if you loosen the engine and move it around a little, as you are lining things up, it helps.

Do you have this order of parts- sprocket, rubber, spokes, rubber, metal piece, bolts?
Do you have the sprocket dished to the inside?

Finally, which way are the two sprockets out of alignment? Is the front sprocket to the right or left of the rear looking from the rear?

 

[Bikeguy Joe]

mright is right- If the rubber parts are deformed, it shouldn't affect the sprocket alignment once tightened properly.

 

[Saddletramp1200]

These are "kits". Ever build model car or airplanes as a kid? Kit to ME is it won't work till YOU make it work. It takes time, understanding and some skill. I do know when you take that first ride, you will feel like Howard Hughs or the Wright Brothers! If was easy it would be boaring to me. Welcome to the Forum.

 

[Cr9ck]

Pretty much.
A derailer chain won't work.

Sometimes if you loosen the engine and move it around a little, as you are lining things up, it helps.

Do you have this order of parts- sprocket, rubber, spokes, rubber, metal piece, bolts?
Do you have the sprocket dished to the inside?

Finally, which way are the two sprockets out of alignment? Is the front sprocket to the right or left of the rear looking from the rear?

yes and yes.

The alignment is to the left of the engine sprocket.

 

[hill climber]

you might try removing the donut on the outside of the spokes, there usually about 3/8" plus with the sprocket against the spokes it will bolt down true. you have already machined out the center hole, should make for any easy install.

 

[Bikeguy Joe]

I'd replace the thicker rubber piece with a thinner piece of rubber or leather if you go that route, metal to metal is a bad way to go.

Run the chain loose if you just can't make it work. 1" freeplay.

 

[Cr9ck]

im about 230 and very afraid I will ruin my wheel by removing the outer donut/rag. we are going to shave it down to size hopefully that will work

 

[jburr36]

Well, I'm probably one of those people who seemed to get really enthusiastic (or pathetically perfectionistic) when it comes to my bike engine thingy.

On my first bike which is now completely disassembled and in a box under my bed I attached the 44 tooth drive sprocket to the spokes as per the kit design. To say the least I really hated it that way. One reason is that the spokes eventually became bent either by the torque from the engine or by me tightening the sprocket onto the spokes. I was concerned about this causing my rim to 'dish' and/or becoming misaligned.

The second reason I hated this setup is that because the chain is attached to the engine's clutch shaft it added a fair amount of resistance when I wanted to just pedal the bike. I felt like I was pedalling up a hill or against the wind.

My solution was to get a wheel hub with a sprocket that screws onto it with a freewheel like this --> bicycle Motorized BIKE GAS ENGINE - 40T freewheel Axle - eBay (item 190258533603 end time Oct-17-08 18:21:00 PDT) however with ths setup I would no longer be able to pedal start the motor which for me is a good thing because I hate having to start it up that way anyhow. Another modification is in order so I had to order a pull start unit like this --> bicycle Motorized BIKE ENGINE parts - pull start - eBay (item 190258704100 end time Oct-18-08 11:02:46 PDT) . *Ehem* another slight problem might occur in that the pedals may not clear the wider part I just attached to the engine so one may have to get a wider pedal crank set like this --> bicycle Motorized BIKE GAS ENGINE parts - wider crank - eBay (item 190258713982 end time Oct-18-08 11:48:07 PDT) to make it work. I didn't do that yet because I'm making new motor mounts that will allow me to mount the engine in a way that clears the pedals. Even though I have the pull start I bought an electric start motor like this --> eBay Motors: Electric Starter For 49cc 2 stroke Super Bike Scooter (item 220290786434 end time Oct-15-08 22:59:23 PDT) that will retrofit onto the magneto cover with some machine work quite nicely. It's just slightly bigger than the pull start mechanism. This project is a work in progress so I'll let all know how it goes later.

 

[Cr9ck]

thanks for the great idea. I would like to be able use the bike without the motor so the freewheel would work nicely. please do let me know. sorry i suck at mechanics how would you install the freewheel hub ? would you have to build a rim and spokes around it?

 

[jburr36]

It's not as easy as it sounds. I have to remove the tire and tube from the rim and then remove all the spokes from the rim and the hub. The new hub I bought is for 36 spoke rims by the way. I have to also remove the freewheel with all the sprockets from the right side. this is the stack of 7 sprockets that is used for the normal pedaling with the crank. I then have to attach the new hub to the rim with the spokes and adjust it to make it true and then screw the stack of 7 sprockets onto the right side and the engine sprocket with the freewheel on the left side. Add tube and tire and that's it.

There are web sites out there that show how to respoke a hub to a rim. I guess they call that 'building a wheel'. This is supposed to be the most challenging part of it.

I had to buy 2 specialized tools to do this. One is the spoke tool to loosen and tighten the nibs and the other tool is the sprocket freewheel removal tool for a Shimano set.

I'm doing a 900 mile engine rebuild at the moment so I haven't gotten that far yet. Still painting parts.

 

[Cr9ck]

yeah i supposed so. only 900 miles? did it die on you?

 

[Bikeguy Joe]

900 miles should just be getting started.

 

[stude13]

why is the sprocket center hole not big enough. havent the vendors been asked?

 

[tyrslider]

jburr36 is that rear sprocket 1/8" or 3/16" do ya know?

 

[jburr36]

The new 40 tooth sprocket that came with the hub is .125" and the stock 44 tooth sprocket is .165" according to my caliper gauge.

The sprocket hole is not big enough because the engine makers know that the hubs they fit over vary in size. My 44 tooth sprocket fit over the hub perfectly. Had it been a bit bigger there would have been issues. They probably wanted to err smaller than bigger because it's more convenient to remove excess metal to make it fit rather than make the hole too big and risk not having it fit at all.

My engine didn't die on me. In fact it was running pretty well. I bought a beach cruiser bike and I wanted to put this motor on it. Since I had 900 miles on it I was really curious to see what kind of wear it had. I also wanted to do a deep inspection to find other issues mainly because of of the problems people are having with theirs. I guess I got a good one for it did just fine.

Also I'm doing other mods to it like adding the electric starter/generator. In the next day or so I will start a thread reporting my progress and findings of this tear-down. I may have found the source of a squeel.

 

[Biker Mike]

I'd replace the thicker rubber piece with a thinner piece of rubber or leather if you go that route, metal to metal is a bad way to go.

Run the chain loose if you just can't make it work. 1" freeplay.

Want to add to your headache? Open your kit and find a sprocket like this staring you in the face. Trying to get replacements.