Honda 125cc Inline 4 Cylinder Monkey Bike
May 30th, 2008 by Paul Crowe - "The Kneeslider"
The little Honda Monkey bikes, the 50cc Z series mini bikes, are pretty popular in some countries. Some fans of the little guy really engineer very nifty modifications, like this 125cc inline 4 cylinder engine for instance. It’s so small it looks like a model but it’s a real engine and sounds great!
Not a lot of detail on their website but very, very cool.
Thanks for the tip, Aaron!
More photos and video below:
Link: Wirthwein Motoren
Posted in Alternative thinking, Custom motorcycles, Engines, Motorcycle Builders
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18 Responses to “Honda 125cc Inline 4 Cylinder Monkey Bike”
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May 30th, 2008 at 11:15 am
That’s amazing.
May 30th, 2008 at 12:22 pm
Where can I get one? This would make a VERY COOL engine to run while having beers in the garage.
May 30th, 2008 at 12:26 pm
It isn’t running at very high rpm like other small inline fours. I wonder what it would be like with four carbs in stead of one… But still very cool. Nice engineering.
May 30th, 2008 at 3:24 pm
Not so different from an Alan Millyard creation but I think he’d have used four carbs. It makes great noise but doesn’t seem to have the oomph! Four carbs = at least a couple hp. Maybe next time they can make a 200cc four and stick it in a CT70 or ST90!
May 30th, 2008 at 3:31 pm
The sound makes me long for my old CB350F. Gawd, I loved that bike.
May 30th, 2008 at 4:13 pm
Why don’t the big manufactures build street-legal fun punky little bikes? The Honda Ruckus comes close but it needs a 100cc engine rather than 49cc (a safety issue with the hills). If this 125cc 4-cylinder bike were street-legal and available in the USA I would buy it in a second as my city scooter.
May 30th, 2008 at 4:19 pm
Honda does make the 250cc Big Ruckus. I hear they’ll do about 75mph on the highway, but I’d still rather have a proper motorcycle.
This little monkey bike is a great example of brilliant engineering!
May 30th, 2008 at 8:18 pm
the rumour is that these guys are working on a v8…
May 30th, 2008 at 10:46 pm
Forget about four carbs.
It would be cool if they could adopt the new Honda Cub 50cc FUEL INJECTION for this. One injector per cylinder.
May 31st, 2008 at 5:59 am
I have my doubts. If you look at the head, I can’t see any way of driving all thoses tiny whiny values?
May 31st, 2008 at 7:30 am
Slap a pair of those together, and give me a V8 250.
May 31st, 2008 at 10:43 am
turbo
June 2nd, 2008 at 9:06 am
That’s brilliant. What a great wail that thing makes!
June 2nd, 2008 at 1:06 pm
Loomis, the cam is run off of a drive belt behind #2 cylinder. There’s a drive “box” back there.
The timing belt looks like a very small toothed drive belt, looks a lot like the drive belts in copiers and medical equipment.
The single cam has a matching drive pulley dead center.
Check the Wirthwein webpage for closeups.
June 2nd, 2008 at 8:07 pm
Why don’t the big manufactures build street-legal fun punky little bikes?
They do. In Thailand and elsewhere in SE Asia. The question is why don’t they import them to North America?
How about doubling up this motor for a 250cc V-8? And twin four-barrel carbs.
August 15th, 2008 at 11:22 pm
Honda competed for the 125 world championship in the ’60s with a FIVE cylinder 125. With five carbs. With four valves per cylinder. But it was built by a factory team and probably worth the equivalent of a quarter million dollars in today money. This is brilliantly done.
August 15th, 2008 at 11:26 pm
Nice to see the Stig fully wrapped for his test ride, too, rather than the usual kid in flip-flops who grins fit to bust until he decks it….
October 7th, 2008 at 12:22 am
Does anyone know what the website is for this engine i tried searching for it but to no prevail. Any info would be nice.