Incremental Chain Tensioning, Chain Management

[Rogwillsie]

mralaska--Thanks much for your info. Can I assume that the threaded rods in the links you sent fit the threads in the motor block? I know nothing about thread sizes so am dependent on someone telling me what to get. Thanks for the suggestion of zinc plated rods. I'm still hopeful I can get the chain working right, without the tensioner.
Rogwillsie

 

[mralaska]

The threaded rods I linked to are M6x1.00 which fit everything on my 50cc. Some of the larger motors have M8 studs for the head bolts but as far as I know they all use the M6 bolts/studs for the mounts.

I determined the size by taking my engine apart then going to the hardware store with the bag of bolts. I did find nuts and bolts to fit or upgrade but I wanted to use studs to make sure I utilized as much of the thread depth in the block as possible. I probably could have got away with available metric bolts but the quality of the metal used for the China castings did not inspire confidence.

 

[Rogwillsie]

mralaska and anyone else who has had the same issue--

Here is my question: why not just use hex head bolts for the motor mounts? I am probably asking this out of ignorance but I don't understand why it is necessary to use the bolts threaded on both ends with one end going into the engine and the other through the bracket and tightened with a nut. Using a bolt seems simpler to me and would accomplish the same thing. What am I missing?

 

[MotorbikeMike]

Bolts vs studs, a question of lifespan

Hi guys, I wanted to answer this one myself. The castings on the Bicycle engine from China are sketchy at best. Even on a quality-built engine we use studs, not bolts, so that the thread wear is the nuts and studs, NOT the castings.

Ultimately, your best bet is stud-locker on the threads inot the castings to insure they do not turn, and wind the nuts on and off as much as you like.

With a little bad luck, winding the bolts in and out of the castings, will wear them till they are loose, and you face early failure.

There are actually places on my new kits that I'm wanting to have studs, for that very reason. (not sure i can source studs for the kits, tho)

The castings are much nicer than the 2=strokes, BUT I am unsure of the alloy, and accuracy of the threads.

Always try to err on the side of saftey.

Mike

 

[Rogwillsie]

Motorbike Mike--Thanks for your prompt answer, now I understand why to use studs rather than bolts. I located some threaded zinc coated M6 at a place called Tacoma Thread in Seattle and will pick it up today. Thanks, again. Rogwillsie in Seattle

 

[jvirginillo]

Chalk me up for a failure of the front mount casting. I used a bolt which cause a crack which now has lead to complete failure. Luckily I have a second motor. Once I replace I will look at options to repair.

Anyone ever filled a hole wol JB weld and tapped it?

 

[Rogwillsie]

I gave the wrong name for the place I found the threaded M6. It should have been Tacoma Screw Products, 3930 Leary Way NW. Seattle.

 

[NunyaBidness]

Chalk me up for a failure of the front mount casting. I used a bolt which cause a crack which now has lead to complete failure. Luckily I have a second motor. Once I replace I will look at options to repair.

Anyone ever filled a hole wol JB weld and tapped it?

I had a stud in the back side of my motor that stripped out. I just put some JB Weld in it, more than I really needed, then screwed the new stud in all the way, JB Weld was oozing out well before the stud was all the way in. Let it set over night, I did the fix late. and it has not been an issue and I've put well over 500 miles on the bike since that fix.

 

[mechanickid]

pics please! lol

 

[Rogwillsie]

I took care of the chain problem, installed the studs after cutting to length and moved the engine so that the chain would be the proper length and I could get rid of the tensioner. Now a new problem. When the chain came off the last time it damaged the spokes and when I took it to the bike shop to have the wheel realligned and some spokes replaced I was told that it would cost more to repair the wheel than to replace the whole wheel. I didn't realize that there was that much damage. The bike mechanic seemed to think the wheel was not strong enought to take the torque of the engine. Wow. I feel like I'm shot out of the water. Has anyone else had this issue? What do I do now?

 

[Bikeguy Joe]

Yes, I think he's trying to sell you a new back wheel. A lot if bicycle shops don't seem to like us motorized bicyclists...something about our purity, ect....

Is the rim toast? How many spokes are damaged?

You can buy spokes and true up your own wheel for a couple of dollars.

 

[mralaska]

I took care of the chain problem, installed the studs after cutting to length and moved the engine so that the chain would be the proper length and I could get rid of the tensioner. Now a new problem. When the chain came off the last time it damaged the spokes and when I took it to the bike shop to have the wheel realligned and some spokes replaced I was told that it would cost more to repair the wheel than to replace the whole wheel. I didn't realize that there was that much damage. The bike mechanic seemed to think the wheel was not strong enought to take the torque of the engine. Wow. I feel like I'm shot out of the water. Has anyone else had this issue? What do I do now?

Once you put an engine in a bicycle, you often lose the support of standard bicycle shops. I have heard of some of them even refusing to sell parts to a motorbicycler for 'safety' and 'liability' reasons. You are pretty much on your own which contributes to the popularity of DIY forums such as this one where members support and help each other where nobody else will.

Your options, as I see them, are to:
1) learn to rebuild it yourself Building Bicycle Wheels by Sheldon Brown
2) replace it (as I did from a junk bicycle)
3) find a motor-friendly shop if possible
4) after repairing/replacing you might consider modifying a spoke protector to fit the engine side, or I have heard of people using an old frisbee to protect the spokes if junk parts are not available. When I had the tensioner on I threw the chain several times and trashed a wheel. Since removing the tensioner I have only thrown the chain once due to some specific alignment problems I had to make the chain quit slapping my fat mountain bike tire, but I had the tire canted away from the chain so it threw toward the outside of the sprocket.

 

[mechanickid]

find an old bike and take the wheels is what i do. as annoying as the chain tensioner is it can do a pretty good job of keeping the chain in place

 

[Saddletramp1200]

It is no secret that some bikes are made of very cheap materials. I got a new bike paid
54.99 for it. It's pretty, shiny, and it's junk. I let a friend ride it and his weight bent the back wheel. I got what I paid for. I only use Schwinn bikes now. Some say they are junk.
Out of four bikes I have sold I have had one call. He had run out of gas. Schwinn is not what it used to be, granted. My second bike A Huffy mtn bike is built like a tank. It's ugly, rides rough and is my favorite bike of all. I call it second chance. It came from a field over grown with weeds. Abandoned and forgotten. Ill put it up against anything anyone is riding.Sometimes old is better.

 

[Rogwillsie]

Thanks, fellas. I plan to go get my wheel from the bikeshop and replace the damaged spokes myself. I'll probably have to take it back for truing. The idea of a spoke protector sounds good, an old frisbee. Are there other types of spoke protectors? Also, I am thinking of attaching the sprocket to the hub somehow so that there is less tension on the spokes. Has anyone done this? How?

 

[Bikeguy Joe]

Tramp- you know when you buy a dept. store bike they only fully tighten about half the spokes?
Then again the paid monkeys who take them out of the box and put everything on wrong don't help those bikes much either. Besides that, yeah, they are pretty much junk when they are "affordable".

I think the manufacturer knows most people will buy 'em, ride 'em a few times and park them in the dust collector, er, garage.