Mini Bike Chain Adjustment Trouble?

The sprockets are brand new.  The guy never started this bikes engine, and I put a brand new chain on.  They are off by ever so slightly.  Plus I am not sure as to how to align them.  Could I add a washer or two on different sides until it lines up, or bend the frame a bit?  I deal alot with engines but I really just got into motorized 2 wheelers this summer.  Took to them like a fish to water but don't have tons of experience, my knowledge is in the actual engines themselves so guidance is needed.

Not to the point where metal fatigue sets in and cracks form.

I don't have the bikes anymore. I had about 5 and then sold them. I enjoyed them, but I am 6 feet tall and 120 lb, so not extremely tall and skinny, so I didn't have a problem contorting into odd shapes on them. For less flexible people, larger people, and such, probably wouldn't enjoy them. The fifth an final bike I acquired, which I wished I had kept, was a mini dirt bike instead of a street bike the the other 4, now that was comfortable, and I would suggest those to anyone. They have the same engine, but they are taller and have suspension, so no contorting to sit on it and smoother ride. The reason I got more street bikes was because there was a racing league at a local track every Saturday where I lived, and they had different classes, stock, modified, over 50cc...etc. I didn't get into t as much as I hoped though. Still wished I kept the dirt bike one, it was great for cruising the community on.

So as for how I liked them, if you can ride the street bikes comfortably, then 5/5 if you race them at a local track, and 4/5 if you cruise around the neighborhood on them, if you don't find them comfortable, 1 or 2/5. The dirt bike ones, 5/5 for everyone, no matter where you ride them. They are fun little toys though as they can be found on bargain finder type sites for $50 - $100 each.

No unfortunately, the guy that I was getting the frame from took the $50 deposit and stopped returning calls and emails. So after that, I couldn't get air in the sails again. Got a 1963 Ford Fairlane 500 I am fixing up now. Might try and make a few 'Ibles from it on how to do body work, or this and that. I really like this car, but I am still somewhat disappointed that I didn't get to finish the bike, I had some great ideas for it too. Oh well.

Also, that bike of yours sounds interesting. If I had an electric one, I would have converted it to gas as well! Haha!

Looks good! Good size too, not too big, not too small. And wouldn't it be easier to go for a bigger engine rather then 2? There is that bike on the Internet someone made with 50 chainsaw engines...I can only imagine how much a pain in the arse it would be to hook up 50 engines together to run one rear wheel...now that I think about it, 2 would be no problem compared to that! Haha! Good luck, I would love to see it when it's done! :)

Make sure they are identical engines, that would help soo much! That way they rev around the same RPM. Both will need clutches that engaged at roughly the same RPM, then some sort of transmission that couples them without slowing/over revving one down if the other runs faster/slower, but allows power from both to be used. I know some helicopters use 2 engines, spinning opposite directions to balance out. Not sure how to do it exactly...

The only easy way to go about this, (Maybe), would be to remove the carbs and install a pipe that connects both intake manifolds and this pipe, at its mid point between the two engines you use one larger carb. This avoids problems with having to try and sync up both carbs. Next, remove the clutches, and have the exact same size gear on both engines and a chain to connect them, that way when one starts, so does the other. This would allow you to have them offset, one at bottom dead center while the other is at top dead center, which would reduce vibrations considerably. You would have to have a clutch on one of them to drive the wheel, but only on one, and it would be independent of the chain that connects the 2 engines, so both engines would stay timed together. Also, use one engine as a "Master" the other as a "Slave". The master would control when it, and the other one (Slave) fires, preferably 1 stroke apart, like before to reduce vibrations. Something like this should allow both engines to run perfectly synced, if they are identical engines to begin with.

So to sum up, you would have to make a pipe that connects the 2 intake manifolds and in its center, as to not favor one engine over another, mount a larger carb. Next you would have to weld on/bolt on a gear on each shaft of the same size and link the two engines with a chain. Time both of them 1 stroke apart. Mount a second ignition coil, exactly 180 degrees from the ignition coil on one of the engines, use the coil from the slave engine. If done very accurately this will fire both engines 180 degrees apart and keep everything synced. Lastly, off of one of the shaft mount the clutch, independent of the chain drive linking the engines, and this will what drives the wheel.

Does this make sense? The way it is set up in that picture, you are trying to sync 2 carbs to give engines the amount of gas they need to run at the same speed, impossible (Almost) to do. Because they both have clutches then linked together, when engaged they could engage firing at the same time, which would make the whole bike shake. Also, without having a feedback system of sorts that can adjust each engine with the other, once both engage, the faster of the 2 engines is driving the wheel and driving the other engine faster and therefore will get less power then a single engine. Its surprising, but if one engine but in the setup in the picture, if one engine runs slower, it will actually cause resistance to the other engine, reducing power.

Sure, I will get right on it! :)

Will post something for you by Wednesday night. Been really busy, plus I want to make sure its a decent diagram. :)

So first, weld 2 identical sprockets right to the crankshaft of each engine so they can be linked with a chain to keep both in time together. Add a clutch to one so that the power can be transmitted to the back wheel. The clutch is independent of the 2 sprockets you welded on to time the engines together. Use one engine to create spark for both (Make sure the spark is timed properly for BOTH engines otherwise one could backfire etc...). Lastly, upgrade the carbs to a larger carburetor and link the 2 engines to that via a pipe. Put that large carb in the middle of the pipe so that it should feed both equally.

When doing the spark, you might be able to use the magneto from each engine for them selves, rather then use one to drive both spark plugs. And when you link the 2 engines with the chain, make sure one has its piston as high as it will go, and the other has the piston as low as it will go. This will greatly reduce vibrations.

Good Luck! I want to see it when its done! :D

That won't work, that will actually give you less power then just one engine. The reason you can't do it this way is no matter how hard you try, one engine is always going to run faster and its going to be driving the wheel as well as trying to turn the second engine faster then it wants to go, so you actually get less power. The only way to do it is to have a transmission unit that couples both engines to one shaft independently of the other.

Ya! Haha! Factories usually avoid making defective products! :P