micro mini bike

#4
Yes it is we have spoke before it is a SST80.Runs sweet would like to register it but cant find out what year it is.I think its a 1970 serial# isM8-02191.Can you post a pic?What year is yours?A few more things and it will be done.
 
#8
Yeah actually it wouldn't be too bad.. I think I would fabricate some kind of (throttle hooks to the governor) set up though.. I just wired right to the throttle plate so I could go wide open.. :scooter: It's a two stroke.. :shrug:

But they do have a wind vane governor about like a briggs 3 horse.. I think I would attach to that some how, so you can keep the RPM's down to a dull roar for little kids..

A jack shaft is gonna be about crucial too... SOME KIND of gear reduction.. They aren't much for torque but they get going pretty good.. They make power at wide open.. :doah:

I think I would aim for 25 miles per hour, at 6,000 RPM's.. Then govern the engine to like 4,000.. Something in that ball park.. That way you have the power to go without issue, but don't burn the engine up rinning it's guts out..

I've got one with a weed whacker engine that pulls me but is only about 7 miles per hour screaming it's guts out.. :laugh:

 
#9
I have admired your home built bike pictured.Very cool home build.There is a jack shaft setup. Is there a formula for gear ratio for jack shafts or would you figure the clutch side then the drive wheel side?Not really sure how to figure it yet.I like the motor bike also nice work.
 
#11
I have admired your home built bike pictured.Very cool home build.There is a jack shaft setup. Is there a formula for gear ratio for jack shafts or would you figure the clutch side then the drive wheel side?Not really sure how to figure it yet.I like the motor bike also nice work.
Yeah, I original posted looking for the 180 degree exhaust pipe for easy install, VS the square muffler too.... But realized I was dumb after looking at the pic again.. :lol: I do that alot... I'm tarded.. :stuart:

Yeah if your motor doesn't utilize the built in centerfugal clutch.. You can direct link the motor to the jack shaft, geared down some, THEN put a standard 5/8 bore Max Torque clutch on the OUT SIDE of the jackshaft, to the wheel... That will allow the engine to spin up more RPMS before the clutch engages, to give ya more torque at take off..
 
#16
I hope so it seemed to run fine in the vise in that position.Been so long cant remember how it was mounted in blower.Its a diaphram type so should be ok.Just doing little more reaserch and the diaphram carb works in any position.Diapram carbs are on chain saws that is why they run in any position.Had me thinking for a min.
 
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#17
Jeep2003

Yeah it should be fine.. Thats the ONLY advantage to those things.. :laugh:

helix95

The ones with clutches are usually on snow blowers too.. :laugh: They were just the old style ones is all.. I would just link the motor to the jack shaft sprocket to sprocket with no clutch, then just put your clutch on the jack shaft and run the wheel with it.. :thumbsup:
 
#19
well half the shaft is 5/8 correct? I would just take a wide flat file to it while its running to shave it down to 5/8 the whole way. then dremel the keyway bigger if you need to. I had to do that a couple times and it worked out good
 
#20
There is a decompression port under a 2 screw cover near the top of the cylinder. Its controlled with a small steel reed valve. They can get fouled with carbon buildup. I remove the reed and block the port by running a tap about halfway to three quaters through the port and stuff in an 8-32 set screw to avoid any of these issues. The exhaust ports also tends to carbon up, Ive seen the three holes close up more than half way with carbon. The carb wont work in that position, if you pull the diaphram and follow the ports and circuits you will see why, old mr. gravity. Another thing is that fuel is important with these, fuel with ethanol will tend to get the piston crown so hot that the incomming charge will burn off and go right out the exhaust port and back into the transfers. The engine will get hot and become sluggish and heat will carry down into the block and if ran for too long will cook the crank seals. The rods in these tend to let go if held at 7500+ rpm for too long. If you can avoid these issues then your good to go:thumbsup:.
 
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