Pocket Bike Engine Project

Strangely, I have been considering a similar engine to plug in on my 31cc 4stroke FD. Will be watching your build closely. Feel like I should load my welder in the car, and come over to give you a crash course in welding. You must get tried of drilling holes. On the other hand, I guess you can unbolt it and shuffle it around for the next project, thats a plus. Any way will be watching to see what kinda magical beast you create this time!

Whats the top RPM, I have heard as high as 11K? If that is the case a 1" roller would show nearly 33mph. Wow!

Youre not going to have a lot of belt in that little pulley, may have to baby the take off. Still an 18:1 ratio is gonna be great because it should pull hard, aka fast from the bottom to the top. The high rpms will make for a good top end.

Yeah, I forgot about you using the idler. Was assuming the relationship for the two pulleys which would make for scant contact in the little pulley. The engine may be weak on the low side, but I bet it has a higher clutch engagement speed and if you were to grab a bunch of throttle initally my gut says it could be a bit of a bear. Ive seen kids squirting the little pocket bikes around and they dont seem to lack power anywhere.

The two strokes are known for having a higher power band then the fours. Fours are great for the lower end but once you go to the dark side and get use to the two stroke you'll have a blast. A plus too with two strokes and Ive come to understand , and Im sure someone willpoint me if Im wrong into the right direction, but two strokes like to revv where as the fours would rather chug at about 3/4. Used the two and four strokes on my boats and in rc things and the two strokes were always my fav's.

Low racer
used the stock cag engine on a friction drive with a 1 1/4" driver roller and it seemed fair. camparing to my "up-right common pocket bike 49CC engines"

then installed the cag engine on my rack mount cvt right hand dual free wheel drive. After a day or two the cag engine would not run, no spark. We spun it with electric drill (with plug removed), used coils of a couple other new cags and could not get spark, we tried hard.

I had a new cag with the red anadized head =52cc. You could sure tell the difference in power and sound. The stock cag engine had a plastic gas tank mounted of top of the engine. When we mounted the tank on the top of big bore 52cc, we did not notice the bigger separate cyclinder head touched the plastic gas tank and melted a hole in the tank. We rode the new 52cc around for an hour or so with the cvt tranny and was impressed. Then the tank melted a hole and i seen the gas running on the ground. Put on a new tank raised up but it would not start.

Then i started building my diy scooter guy type shifter build with the hs titan 4 stroke which is awsum. I must have about a dozen of the new cag motors in my china closet!! Lol.

Kinda like the king that had 10 wives, 9 of them had things pretty soft.

Took the bell housing with the little sprocket and dis-assembled it. Took the shaft with the little "tiny 9 tooth" sprocket and screws into the clutch drum to a machinist and had him machine the sprocket and little shaft off level with the out side of the housing where the support cap and bearing bolts on.

Then he drilled and tapped the shaft 5/16' nf thread. Used a 1" long allen head set screw and attached a golden eagle 25 tooth cog for the cogged belt. Now that looks nice in one of my parts drawers!

After several months thinking about how to use the bell housing it came to me laying bet one morning, so simple and cheap. Paid him a 12 pk of mountain dew.

Have posted the pics before, cant repost them. Can resize or retake easy if anyone wants to see them. Have a kawasacki 49cc polished alum engine with the double bearings like you have from staton. Which cost near a hundred with sh. Many of the cag engines come with the little bell housing, it will be a couple inch`s narrower which may help.

Ron

lowracer

Most of the 49cc cag motor`s come without gas tank. That engine did have a gas tank. It was a couple years ago. I pulled a inner thigh muscle and can`t go out to shop for a couple days. I need to find a good repair method for the white plastic looking tanks.

Will post some of the pics I took a couple days ago. Was sorta waiting for approval for posting pic`s on your thread. The pic`s are explained in my previous post.

Will try to get tank info to you later. I have never even checked to see if any of my
49cc cag engines have reed valves! I do have hopes of mounting my cags.

Ron____________________________________!

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Also;

I had the dime size sprocket that use`s #25 chain cut off the clutch drum shaft. Then bored and 5/16" nf thread`s tapped into clutch shaft. Then the 1 inch dia belt cog can be attached, and use other tooth count cogs.

My plan is also to use a longer allen set screw, have end machined to fit into the 1/4" id bearing in the support cap/


The clutch shaft could be bored and threaded @ 3/8" with no proplem, maybe even 7/16" with a stable outer support bearing. The shaft is 5/8" with a short shoulder so it will clamp main sealed bearing against clutch drum. We left just enough shoulder so cog clears housing. Thin shaft spacer`s can be purchased.

If the whizzer type wheel sheave is used, my thinking is to secure a 3/8" wide v belt in the 1/2" channel to provide grip for a cogged belt, don`t forget a moderate spring tension = tensioner.

Or if bicycle rim is modified for a wheel sheave, secure a length flat belt in the channel.

All of this effort is to save a buck of course and narrow engine width.


Ron

Lowracer

Looking good. Does the engine need much help getting going?? The more help it needs starting out, the less it will rev when cruising.

Have been wondering if the flywheel fan blowing on just one side of the cylinder is problematic. When using one of mine again, plan on making a full shroud with a couple soda cans or something. just a thought. Almost thinking a lack of fan would be better than cooling one side, but am not sure.

Been thinking of trying a wide rim fastened to rear wheel rim for tire clearance. the belt should track to the left to align with engine cog/pulley.

You no doubt have a lot of guy`s thinking about simular builds. Thanks for sharing.

Ron

Hey Lowracer, how is it on vibes?

Wow!

50mph is FAST !

(I'd be trying to slow it down some, and improve my start-off a bit in the meantime!)

Good luck with that!
rc