2-Stroke ****!!!

Cyclin · Jul 13, 2011

So this was my first motorized bicycle which I expected there may be some issues with due to lack of experience. I am using a beach cruiser I had in the backyard and an 80cc engine kit I purchased from PCC Motors. First I sanded off the original paint and any rust I found, then applied the new paint (Rustoleum).

I purchased a brand new chain for the manual pedals and installed it. After securing the engine and the rest of the parts, I took it on my first, and incredibly short, ride. As I was cruising along the chain slipped causing the back wheel to lock up which snapped the rear axle as well as the master link of the engine chain. I then took the bike to my nearest bike shop and had them install a new rear wheel, this time with no coaster brake, as well as a handbrake. I also had the mechanic there install the engine sprocket for me as he had more experience doing so.

After tinkering around with the throttle we had the bike up and running yesterday just fine. I took it on a short 3 block ride when the chain fell off once again. I hooked it back up, increased the chain tension slightly, and had no further problems for another 7 blocks or so.

The chain slipped once more and the rear wheel locked up, this time being forcefully jerked by the engine about 5 inches out of the frame to the left. (My knee hurts a lot now.) When this happened the muffler bent down and slightly horizontal and had broken off at the weld.

What should I do??? (Pictures soon)

GearNut · Jul 13, 2011

After repairing yourself and the muffler weld, I recommend checking the alignment of the sprockets as well as the centering of the rear wheel engine sprocket, and the alignment of the chain tensioner. Also get rid of the kit supplied chain. They are garbage and are known for having stiff links which will not allow the chain to wrap around the sprockets properly.
Things that will cause a chain to get thrown that easily are one or a combination of all of the below problems.

Sprockets out of alignment will cause the chain to run crooked.
Sprocket not centered on the rear wheel will cause the chain tension to rapidly change from tight too loose.
Tensioner wheel not aligned to chain will cause the chain to run a little bit crooked even though the sprockets are aligned.

ferball · Jul 13, 2011

The broken weld is the perfect excuse to go by yourself a cheap welder, or you could take it to a local weld shop and they could put it back together for you cost you little or nothing for the 30 seconds it will take them to fix it.

For the chain issue check your alignment when you remount your engine, do a search of the forum I am sure somebody has posted a how to on that some where. If it was a single speed cruiser the drop outs should allow you enough adjustment to remove the chain tensioner all together.

That is what I would do, but I am only right 18% of the time.

Venice Motor Bikes · Jul 13, 2011

The rear sprocket needs to be installed perfectly centered & without any side to side wobble! Then you can also file the sides of the sprocket teeth so that they will feed into the chain without snagging the sides of the links & causing it to jump off.

Al.Fisherman · Jul 13, 2011

Venice Motor Bikes said:
The rear sprocket needs to be installed perfectly centered & without any side to side wobble! Then you can also file the sides of the sprocket teeth so that they will feed into the chain without snagging the sides of the links & causing it to jump off.

Also
This is how I did mine.... ‪Bearing cap mod‬&rlm; - YouTube

A 4" or bench grinder will bevel the edges (just to get the sharpness out of the teeth)..both sides. Some have used a file. ugg too much work.

The_Aleman · Jul 13, 2011

Besides the chain needing to be straight and sprockets centered, I think a lot of people these days are using bikes with improper dropouts for motorizing.
When you use bikes with semi-horizontal front-exit dropouts, it's entirely possible for the wheel to get pulled at an angle under abrupt power.
Like when starting a chinagirl with excellent compression, and not wanting to fire up.

There goes your chain. Heck, I've done it many times just pedaling on that kind of junk

Norco John · Jul 13, 2011

Had the same thing happen to me when I first built mine.
The kit chain looks like it was put together by 2 kindergartners working with a can of parts, 2 nails and a rock.
Go to the farm store and buy a chunk of #41 chain, a chainbreaker, and some master links.

Goat Herder · Jul 13, 2011

The_Aleman said:
Besides the chain needing to be straight and sprockets centered, I think a lot of people these days are using bikes with improper dropouts for motorizing.
When you use bikes with semi-horizontal front-exit dropouts, it's entirely possible for the wheel to get pulled at an angle under abrupt power.
Like when starting a chinagirl with excellent compression, and not wanting to fire up.

There goes your chain. Heck, I've done it many times just pedaling on that kind of junk

Need to mebbe incorporate something like these? bmx chain adjusters - Google Search

The_Aleman · Jul 13, 2011

Yeah, something is better than nothing. Most of those chain adjusters are for horizontal rear-exit dropouts tho, which is my own preferred dropout.
The wheel can't be pulled out of the dropout under power with those dropouts.

Goat Herder said:
Need to mebbe incorporate something like these? bmx chain adjusters - Google Search

2door · Jul 13, 2011

I agree with the first response from Gearnut. Improper chain/sprocket/tensioner alignment is responsible for most chain problems. The parts of the drive system must be in alignment for it to work properly. Any misalignment is going to cause trouble.
A chain drive must me aligned. That means every component must align with the others.
Chains aren't like belts. They only like straight lines.
The other issue is the rear, driven sprocket. It MUST be centered on the rear hub and have no wobbles, horizontal or verticle.
Tom

Al.Fisherman · Jul 14, 2011

Believe it or not, I'm still running the factory chain. I had bought a chain from Tractor Supply, but ended up using it on my son's Chopper. Had not ever gotten around to buying a new one since TS is 30 miles away. Dirt bike shops didn't have them. Stout and strong since August 2009. Rear sprocket installed as I did in the video, and perfect alignment. Maybe I'll get around to changing the chain one day, but if it aint broken, leave it alone.....right?

Cyclin · Jul 15, 2011

Thank you everybody for all of the advice! Its so great so many people are passionate about this hobby!

Well, I have checked the rear sprocket and it is perfectly centered. I even measured each edge with digital calipers to the .001 of an inch. When you guys says grind the sprocket teeth do you mean the small engine sprocket or the large rear wheel one? I still have a bench grinder in the shed which I've been dying for an excuse to haul out and use but am not adverse to doing it by hand as then I wouldnt have to remove the sprocket again.

Over the weekend I'm going to replace the muffler and this time secure it with some added brackets and replace the chain.

I havent been able to find any chain at my local bike and motorcycle shops that match the 415 weight chain that came stock. Any suggestions for alternative chains? I don't really mind having to purchase another but would rather not have to order.

When I first posted this thread I had already emailed PCC Motoparts and they have sent out a new chain and muffler so those should be here in the next few days. I am taking the original muffler to a local welding shop to see if they can re-attach and strengthen the weld.

GearNut · Jul 15, 2011

Usually a KMC410H bicycle chain will work. Most BMX bicycle stores sell it as it is quite popular on the BMX racing scene. If it does not have the "H" suffix, do not buy it. It will not be strong enough. (H = heavy duty, thicker plates and stronger pins)

By recommending that you grind on the sprocket, I mean only do that if the chain is showing problems wrapping smoothly around the sprocket teeth, IE getting hung up on the tips of the teeth.
Usually all one has to do is file or very lovingly and gently grind the teeth skinnier on the very tip of the teeth 45* angle, front and back, not in between the teeth. It does not take much shaping at all, a little bit can make a huge difference.

If you are having an issue with the engine sprocket, I had one where the teeth were made too tall. The chain would get hung up traveling down into the valleys of the teeth and back up and out. I created a rig to hold it very well centered on a bolt and spun it up in my drill press while carefully grinding it with an angle grinder.
Leather gloves, face shield, and apron were judicially employed on that one!
I had to angle the tips of the now shortened teeth as well.

All that said,
How well are the sprockets aligned to each other, front to back.

Looking from the rear sprocket to the front sprocket, sight down them as if you were aiming a rifle. they need to be within alignment of each other by no more than 1/16 of an inch, less if possible.

flybytaco · Jul 15, 2011

sounds like youve had a terrible first experiance!!! sorry to hear that man. seems like the ragjoints sprockets dont like to hold a chain well yuo should invest in a spkt adaptor. good luck with your ride and welcome to the forum. there are many talented people here that can help you with anything you may come across. dont hesitate to ask..
TACO

Cyclin · Jul 18, 2011

Ok I have grabbed my file and am about to go to work on the sprocket. The new chain and muffler just got here today. It wraps smoothly enough so I'm just going to lightly file the end of each sprocket tooth so the edges of each tooth is not as sharp. The little adapter bracket for the lower frame engine mount is crap, and didn't do much when the engine popped out during that ill-fated ride.

So I'm gonna head over to the engine mounting section of the forum and browse around for some tips mounting the engine more securely. This time I should be able to lower the front end of the engine about 3/4 inch which should help the chain sit more horizontal. Since right now the engine is loose in the frame I am going to re-align the sprockets when I remount the engine as per your suggestion GearNut. I don't think they were aligned just right the first time.

Thanks for the welcome taco, ya my first experience has not been the best so far but has not deterred me too much in my new hobby. I hope to be putting around to work by the end of the week if not sooner!

Oh well, I'll let you guys know how it works out, and I'll be sure to ask if anything else pops up *Knock on wood*

MarkSumpter · Jul 18, 2011

Do yourself a favor and get a universal front mount or fab one out if 1 1/8' tube steel and weld it to the frame with a drilled mounting plate and trash the rag joint, sprocket and chain you got in the kit and get a good sprocket adapter with machined sprocket and good quality 415 chain. Just makes these bikes so much better all around.

Cyclin · Aug 2, 2011

Just an update... I remounted the engine, installed new muffler and chain, and my bike has been running great!

I'm riding it back and forth from work which is 10-15 miles away from my house. Had a small throttle issue where the pin inside broke but secured it better by drilling another hole and instering a tight dowel. Will post photos soon but not sure what section of the forum is the "success, now check it out" section.

Venice Motor Bikes · Aug 2, 2011

That's great to hear!! (^)

Not enough people follow up & post about it after it's fixed!

his196 · Aug 3, 2011

For added feel-goody-ness about your whole drive train -

Try adding a spring loaded tensioner like in the pics I'm including.

The BIGGEST benefit is I just about completely eliminated the upper chain going tight/slack/tight/slack AND any lateral movement!

This totally fixed my chain popping off problem for sure!

Happy riding, links below.

https://picasaweb.google.com/110058597097031274715/BikeChainTensioner#5634533575140086994

https://picasaweb.google.com/110058597097031274715/BikeChainTensioner#5634533565899568802

Cyclin · Aug 4, 2011

That chain tensioner is sweet!! Im still using the stock one which is basically just a bracket, a bearing, and a wheel.

Where do you get those?

Oh and another 2 stroke **** update, the day before yesterday the back tire got a tiny piece of glass in it and busted the inner tube. Fixed it that day. And today muffler #2 snapped off right above the weld. I took them both to a welder to be repaired and he said that the tube leading to the main area of the muffler was made out of metal that was too thin for the weight of the bottom section. I reinstalled one of the mufflers I had repaired today until I can find a more suitable replacement.

So my second question of the post is; Where can I purchase just the muffler itself? Id prefer to order it online if possible.

And yes I am trying to upgrade the muffler not just purchase another of the same quality.

Thanks for all of your help guys

2-Stroke ****!!!

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