Need help & advice getting an old B&S Mini bike running

#1
This is an old B&S mini bike that I had as a kid that has sat unused in my mother's garage for about 30 years. I want to get it running for my son, but I don't have any experience working on these. (Thanks for your patience.) Amazing that it started right off the bat after sitting for that long. I drained the old oil and put in new. The exhaust is pretty blue, so I am guessing at some point I may need to do some real work on the engine, but I would like to hold off on that for now if possible.

1. Somehow the first chain from the drive shaft/clutch is missing. The sprocket on the drive shaft has 12 gears. Is a #35 chain the correct size, and does anyone know the length?
2. The choke is very loose and will move on it's own when the engine is running. If you look close there is a small crack in it. I am not sure if this can be tightened or it if needs to be replaced?
3. The starter was replaced from the original. The top bolt is missing. Can I use any bolt that fits or does it engage more than just the cover?
4. Is the throttle supposed to have a spring on it?
5. The original throttle cable is missing (it was coiled metal). It looks like it needs a cable just over three feet. Would the "Universal throttle cable" 48 inch work?
https://www.gokartsupply.com/thcable.htm
6. The original twist grip is missing some hardware. Is the "cable adjuster for mini bike throttle" the part I need?
https://www.gokartsupply.com/mbparts.htm

Thanks for your time and attention.
 

Attachments

old shed finds

Well-Known Member
#2
Sounds like a neat project.
1st thing change eng oil 30W.
Top shroud bolt is SAE coarse thread.
Yea needs throttle return spring.
Yea you are #35 chain Ebay 9.95 for 3 feet..
Choke ?? Im unsure. Never seen a updraft choke do this problem?
Usually a junky old bicycle will have the cable couples you need..
Sounds like a fun project to me.....
 
#6
So, I couldn't find the model number, but I found the old flywheel cover/pull start. It looks like the number is 81302-943541-59052.
It looks like this is a 1959 engine. I also found an old manual in the basement.

It looks like this mini bike is a K&S Hardtail Deluxe. Interestingly, they came with Tecumseh engines and there was a Tecumseh manual where I found this one.

I managed to get the broken throttle screw out without drilling it. I took the carburetor off and when I removed the choke lever, there was just enough broken bolt standing proud that I could score it with a hacksaw and back it out with a screwdriver. 20200502_211828.jpg 20200503_152832.jpg
 

rugblaster

Active Member
#7
I've got a very good reproduction of the "HORNET" decal which adored the front fork of these bikes. PM me your address and I'll send you one.....freebee!!!!
 

Harquebus

Well-Known Member
#11
1. Don't worry about fitting the proper chain length, just buy more #35 chain than you need and 'cut' it to fit with a decent a chain breaker tool and get yourself proficient in breaking chain. As to finding the proper length of chain, you need to factor in that the slotted holes for the engine on the mounting plate is your chain adjuster. As the chain wears, you typically slide the engine forward and re-tighten the bolts. *Or slide it backward some, since you must have some chain slack for proper operation.

Don't have your engine mounted all the way forward when you measure your chain or you won't leave any room for chain adjustment. Hope this makes sense.

2. Not sure. Ebay is your friend though, for all kinds of new and used Briggs parts.
3. That's usually a 1/4-20 screw but yes, it only holds the blower/starter housing on.
4. Yes, your throttle needs a throttle return spring.
5. Should work. You want some excess cable so you can turn the handlebars lock to lock and not have any binding. A sewing tape measure is handy for this, as you can place it along the bike's frame and estimate the length you need.
6. Looks like that is the missing part. Hopefully the threads match.

I'd use the old starter/blower housing. THAT one shows your actual engine ID. The white one appears to be from a vertical shaft engine (a pushmower most likely).


Any updates?
 
#12
1. Don't worry about fitting the proper chain length, just buy more #35 chain than you need and 'cut' it to fit with a decent a chain breaker tool and get yourself proficient in breaking chain. As to finding the proper length of chain, you need to factor in that the slotted holes for the engine on the mounting plate is your chain adjuster. As the chain wears, you typically slide the engine forward and re-tighten the bolts. *Or slide it backward some, since you must have some chain slack for proper operation.

Don't have your engine mounted all the way forward when you measure your chain or you won't leave any room for chain adjustment. Hope this makes sense.

2. Not sure. Ebay is your friend though, for all kinds of new and used Briggs parts.
3. That's usually a 1/4-20 screw but yes, it only holds the blower/starter housing on.
4. Yes, your throttle needs a throttle return spring.
5. Should work. You want some excess cable so you can turn the handlebars lock to lock and not have any binding. A sewing tape measure is handy for this, as you can place it along the bike's frame and estimate the length you need.
6. Looks like that is the missing part. Hopefully the threads match.

I'd use the old starter/blower housing. THAT one shows your actual engine ID. The white one appears to be from a vertical shaft engine (a pushmower most likely).


Any updates?
Well, I got sidetracked for awhile, but I am back at it.

All the retaining tabs (that hold the starter pulley in place) were all broken off the original starter. I have been having a lot of trouble with the replacement starter too. I have had to disassemble and reassemble a bunch of times. As a result, one of the three tabs is broken and the other two are about to break. Is there an option other than trying to get another whole replacement blower/starter housing?
 
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