Not quite a mini...

#1
Not quite a minibike (this is an old photo), but hey, 42mph max top speed, & street legal in CT without reg or insurance... you only need a driver's license. I pulled an average of 110mpg when cruising at 28mph.

I had just under 4000 miles on this engine before the bearings finally ate themselves (cheapo-china bearings). This was an unknown 48cc (confirmed) HT (Happy Time) engine that had some mileage on it prior to my owning it. I had gone through the engine, ported, mildly polished (steel wool), & balanced the rather beefy little crank & flyweights on the lathe. Planed the head & top of the jug down, & deleted the head gasket. Cut a new squish-band on the mill. Grade 8 metric hardware throughout. Surprisingly, the old NT carburetor was dead-on with just a little fiddling.

Required 93 octane, zero exceptions. It did NOT like anything below that. I always ran it on 32:1 with Opti2 after I ran 25:1 with the cheapo-Wally-world Supertech 2-cycle oil.

The frame upon further inspection began to crack at the head-tube weld. Aluminum Huffy frame, and not worth the effort to TIG up. :eek:hmy:


And yes, the chain tensioner was taken off shortly after the photo was taken besides it being on the wrong way in the first place (how I got it!). The stock ones suck, and I shortened the chain enough to run it without one.



It was a fun ride that was a ton of fun to buzz around on this last summer. :scooter:
 
#2
I had a stock one I easily put over 1,000 miles on before it giving up the ghost. I used a raleigh retro glide frame, and some continental white walls and rode hell out of it.
 
#3
Tx, I found the trick to making these little HT engines last, is that you really do kinda have to get in the motor & clean things up. I had one engine last only 200mi. before it crapped out. Opened it up, & surprise... all sorts of nasty junk. I've found some that have had bad seals from the factory (go lean right from the get-go & blow), and ones that had all sorts of nasty crap. One was rumored to have a cigarette butt in it.

If you really want to build a reliable HT, you have to get inside of the engine... it kind of sucks, but they are cool, and they're fun to ride once they're right. Mine never failed to start once I got it dialed in, and ran GREAT.

I figure 4000 miles & then even more is OK for a chinky china motor. It's a far cry from my sportster, but it did outrun a Motobecane 50V... :scooter:



ALSO, the stock bottom end bearings on the crank pin are A-OK. The wrist pin bearings on the other hand are fine as long as you don't wind up over 6000RPM's on a daily basis or race the snot out of it. There are better aftermarket wristpin bearings for cheap however that feature much, much stronger needles & cages.
 
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