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Old 07-28-2012, 11:59 PM
zeeohsix zeeohsix is offline
Motorized Bicycle Newbie
Join Date: Jul 2012
Location: Long Island, NY
Posts: 11
Default Re: New to 2 cycle engines

Originally Posted by Pawnrae View Post
Hey all, I recently built myself a mountain bike with a Chinese? "80cc" engine kit that I got from a vendor in town. So far I have a bunch of questions seeing as I'm not very familiar with building these from scratch, I am more the computer type . Thus far what I have for questions are as follows.

Bearings in the crank case / drive train
Which ones are problematic and what parts i might need

Jack-shaft kits
How reliable and usable are these and how will it affect regular pedalling

Alternative rear wheels with better sprocket mounting options.
Belt drive is awesome for the road and path rider, but for off road dirt and gravel type areas, I would like to move away from the pineapple rag's. any suggestions?
(26" 700c size)

2 cycle oils
many different types and which type specifically i should use.

other lubricants/additives
what will help the performance of my engine all around.

separate oil and gas tanks for 2 cycle set-ups\
is this even possible to have these mix at a carb or one of these boost bottle kits I have seen around. Ideally for gas on the go and commuting.

lighting kits and such.
I am looking for motorcycle equivalent possibilities run on led to hopefully be able to keep enough of a charge in a battery from daytime riding when that maybe hour or two comes up at night.

very functional add on pieces.
In my travels around where i live i came across one store that deals strictly with electric that carries a unit for dual cable pulling action. it has 2 separate inputs that operate a dual output in unison. I have looked at it and so far i think for braking it should work awesome with the lever set I plan to order. If you have found other pieces/"gadgets" like this what are they and what do they do.

rear and front gear racks.
such a very limited and for my ideal set-up kind of lacking, have you found anything or anywhere that has "spectacular" hardware in this area.

Ill add more when i think of it, and pictures of my bike after i take them.

Okay, I'm going to answer these the best I can. Keep in mind I'm a relatively experienced small and large engine "out-of-necessity" and hobbyist mechanic. My bike is a '76 Columbia Gold Crest (Schwinn Stingray knock-off) with a Chinese 80cc 2 Stroke with 20" wheels.

1. Bearings- I'm going to assume yours is an 80cc like mine (a popular size), and this point applies to the smaller 66 and 49cc motors as well. Sometimes small engines such as these don't have bearings. However, even though I cannot say for sure that this is true, because I haven't *knock on wood* had the need to tear down my motor, but from what I've read these do have connecting rod bearings. As long as you keep up the proper lubrication and don't beat the crap out of the motor, I don't see why yours would fail. In the case it does, however, these are relatively easy to tear down (4 bolts in the head hold the entire top end together, plus side access covers for the clutch, magneto and bottom end). Like I said, I haven't had to tear it down and I only know because I had to rotate my head 90 degrees to make for easy access to the spark plug--mine was a VERY tight fit; I couldn't even fit the carb and had to make my own custom intake manifold out of copper plumbing pipe to fit it.

2. Jack-Shaft Kits- I haven't even attempted a Jack-Shaft kit on mine because everything on this bike is a tight fit, and I literally don't have room for anything more on it. However, most of the Jack-Shaft bikes I've seen are mountain bikes and use the (I believe, could be mistaken) $144 SBP (Sick Bike Parts) kit. As far as how it affects pedaling, again, I couldn't honestly tell you.

3. Alternative Rear Wheels- Unless you find a wheel with a hub designed specifically for mounting the sprocket, I don't think you're going to find much differentiation in wheels. They're all a pain in the ass to mount to, but if you're lucky and good with your hands you can mount the sprocket in roughly 15 minutes.

4. 2-Stroke [Cycle] Oil- Personally, for both the break-in and regular oil I use Smokeless Semi-Synthetic 2 Stroke oil available at AutoZone. Comes in a little 2.6 oz. black bottle. For the break in I used a 16:1 mixture (approx. 0.75 oz oil for 12 oz of 87 Octane gasoline) and afterwards I used a 20:1 mixture (approx 0.6 oz oil for 12 oz of 87 Octane gasoline).

5. Other Lubricants/Additives- I don't use any personally. Maybe after running it for a while, spray some Sea-Foam or Gumout in the carb, or even pull it apart for cleaning (it's not very hard to do). Maybe some CRC Marine Formula 6-56 in the combustion chamber (pull the spark plug, spray the 6-56 in the chamber, and crank it with the plug out to move it around) every now and then.

6. Separate Oil/Gas Tanks/Boost Bottle- I think it's a cool idea, but kind of unnecessary for the amount of oil you'll be using. If you look back to my mixture information from earlier in the post you'll see what I mean. I pour my oil in one of those 15ml plastic medicine cups to mix it; that's how little I use per mixture (I usually do it in 12 oz mixtures at a time). As far as a boost bottle goes, I think you might be a little confused on the concept of what it does. What they do is really act as a device to prevent the return of the mixture that's lost in the combustion cycle in order to prevent a too-rich mixture entering the combustion chamber.

7. Lighting Kits- This one is fairly easy. Your engine should have a 6V generator built in, with the (usually) white wire coming off the coil for your output. This is enough to run a headlight/tail light combo that's available as a kit on ebay for $27.99 []

8. Add-Ons- To be completely honest I've never heard of such a device, although I have no doubt it exists and functions as you describe. I've had no reason to go into research on that as I only run a single rear brake. It sounds very interesting though, and I think you should definitely look into it.

9. Gear Racks- I'm sure these are readily available on the 'net, and if they aren't, it should be fairly easy to fabricate something.

I hope this is of some help to you.

Best of luck,

Due to inflation, your two cents no longer matter.

Current project: OCC Chopper, plans:

-Briggs & Stratton 5 HP 4 stroke, electric start
-Smog pump supercharger
-disc brake conversion
-tachometer & boost gauge

1976 Columbia Gold Crest (Stingray knock-off), 80cc Chinese 2 Stroke. Custom intake manifold, engine mounts, rim brake, digital tachometer. Stock front tire & larger back wheel with wide street tire.
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