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Edited Date/Time
10/9/2020 4:23pm
Anyone here into vintage mini bikes?
And by vintage I mean the stuff from the mid 60s to early 70s that used lawnmower or chain saw engines. Some of the bikes were Taco, Bonanza, Rupp, Flexo, Lil Indian, Arctic Cat, etc. (I am excluding the more modern stuff that came later from the Japanese like the Honda Monkey bike (Z50), etc. Save that for another thread)
There was a time when every neighborhood was alive with the sound of kids buzzing around on these things ... usually after seeing an ad for one at the back of a comic book or magazine and pleading with the parents to get one.
I remember them well and have seen an upsurge of interest in them the last 5-10 years. In LA I go to a show every year and they are all out on display in a nice park setting. Very cool to see. Towards the end of the show everyone fires them up and revs them out. You have two minutes of pure mini bike mayhem.
I'm starting to toy with the idea of putting one together. Since I'm a two stroke guy my main interest would be in a smoker rather than a four stroke. I remember as a kid on my Briggs powered Taco 22 being awed by older kids that had a West Bend, Power Products or even a McCulloch, with the infamous Mac101 being the grand daddy of engines.
But I got lots of questions, so who is into this stuff? Maybe some of you used those motors in a go kart even?
And by vintage I mean the stuff from the mid 60s to early 70s that used lawnmower or chain saw engines. Some of the bikes were Taco, Bonanza, Rupp, Flexo, Lil Indian, Arctic Cat, etc. (I am excluding the more modern stuff that came later from the Japanese like the Honda Monkey bike (Z50), etc. Save that for another thread)
There was a time when every neighborhood was alive with the sound of kids buzzing around on these things ... usually after seeing an ad for one at the back of a comic book or magazine and pleading with the parents to get one.
I remember them well and have seen an upsurge of interest in them the last 5-10 years. In LA I go to a show every year and they are all out on display in a nice park setting. Very cool to see. Towards the end of the show everyone fires them up and revs them out. You have two minutes of pure mini bike mayhem.
I'm starting to toy with the idea of putting one together. Since I'm a two stroke guy my main interest would be in a smoker rather than a four stroke. I remember as a kid on my Briggs powered Taco 22 being awed by older kids that had a West Bend, Power Products or even a McCulloch, with the infamous Mac101 being the grand daddy of engines.
But I got lots of questions, so who is into this stuff? Maybe some of you used those motors in a go kart even?
I have no idea what kind of power they would have in a mini bike and the ratings are all over the map. The WB 820 seems to vary from 6.5 to 10 hp. Wiki shows the MC-101B as 12.5 hp.
How did you obtain your motor and what kind of shape is it in? I imagine parts are somewhat scarce.
Here's a pretty wild build of twin 820s -
The Shop
I also checked out the RLV site. May contact them and see if people have adapted them to mini bikes.
Back in the day everyone seemed to use those short little Azusa headers. Which would still leave your ears ringing after a ride!
Actually, my first attempt riding a 'doodlebug' was on a direct drive and a total disaster. With direct drive, slowing to a near stop and turning is a real art without stalling it. A friend of my older brother was letting some of us try his direct drive but they would stall it every time they slowed down too much. And then the whole bump start chore would have to be done.
I was way too young at the time but gave it a try (wearing shorts, t-shirt and bare feet). Everything went fine until I had to turn around at the end of the street. Determined not to stall it I gave it gas ... way too much gas and slammed into a low brick wall. That resulted in the first of MANY trips to my nearest friends house bleeding to death at their front door and a trip to the emergency room.
Pause it and slo-mo right as the rider gets close and note the perfect form ... even going so far as to help weight the front wheel with his tongue.
I had a blast on that old death trap, and I really wish I had some pictures of it.
I have a basket case Sears that uses a 4hp B&S. It was mine from new, but needs a rebuild. Anybody know where I can source one of those friction brake shoes that rubbed up against the rear tire to stop? High tech!
H
Need to decide if I will go with a Bender or a Mac.
I think a 101 (Mac) would have the edge on power over an 820 given identical builds but lots of different factors besides performance to consider ... engine and parts availability, reliability, cost, vintage value, etc.
Another question is where do I ride the thing? Not going to be popular with the neighborhood if running one of those earsplitting Azusa headers! Was thinking I could drag it along out to the local tracks and maybe wring it out on the kids track or in the pits?
A couple of Mac powered rides -
Also this super clean Hodaka powered Bonanza would probably stomp every minibike out there ...
but it's more of a miniature dirt bike now than a minibike.
Had a 140cc motor with 4-speed manual transmission. It was a shit-ton of fun.
I am 210#, and it would do 50 mph.
Pit Row
Detroit and Milwaukee are both huge in the minibike scene currently, I'm pretty surprised at how popular they are here.
Detroit is primarily drag racing, people build some serious bikes here and race them at Milan and Ubly. A few manufacturers were from the Detroit area so there is good support and lots of resources for restorations.
Milwaukee... people race them on flat tracks, in parking lots, in front of the Harley Museum, and even through bars. I'm #138 on my Lil Indian here, at the time it was clone powered. I completely rebuilt it over the covid lockdown, powdercoated frame, Briggs World Formula motor, bunch of blingy accessories, and I have a 2 speed setup on it currently but it was quicker with a good single speed clutch.
Another video from the weekend. This was the first night of the Flat out Friday weekend, all the events were cancelled but races like this popped up all over the city. There is also a video that made it on Sportscenter of a porta potty going around a roundabout, I'm in that too. lol
I really appreciate Milwaukee as a city for this kind of stuff. They don't take themselves too seriously and really embrace the motorcycle culture.
So where's the smokers?
Hey! No snickering ... when he wanted to the Hoss could lay it down.
Take that Mikeyyy !!!
Or are you gonna argue with the King of Cool himself -
BTW - Looks like Stevie has a left foot ouchie there.
So where are all the karting guys? Somebody jump on that's familiar with Macs.
Of course pops would never get me one...
I don't know a lot about Macs but I do know they have a larger reed cage than an 820 so I picked one up off ebay . The cage on the left obviously. I think it's the main reason a stock 100cc mac is more powerful than a stock 820 which is 134cc .
I know that people have modified their 820 manifolds to accept the mac cage so I'm going to have to hit some kart forums to get some tips.
The other pic is the parts I have gathered for my 820 build .
Should be fun .
Sorry that pic of the parts was blurry. And the other pic here is the bore of the 820 block. I think the stock ports should be fine with the increase in air/fuel of the mac cage but I'll find out more from the vintage kart experts.
But once you start in with the mods the 820s can be competitive. I see chatter on the 820s re the "Bonbright modified Coppeheads". Maybe you're familiar with this stuff? It sounds like Dave Bonbright is / was one of the more respected tuners for Benders.
Here's a comment from a Mac 101 vs WB 820 thread - "Bonbright's "vintage 820s" (same as the copperhead except without the enlarged head/shroud and special paint) on alky and with a good pipe will run just fine with the stock 101's I have experience with."
Also, it sounds like they often just throw a second carb on a stock 820 and run alcohol for a dramatic performance gain.
Of course, I'm not going to be racing a kart so I also need some practical advice such as cost, parts availability, reliability, etc.
Gotta think there are some vintage karters somewhere on Vital ...
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