Big single cylinder motorcycle engine?

[Elliot Naess]

All kinds of gearheads on this board, no doubt, so I'll bounce this off'a ya:

Can you name a large single-cylinder ("thumper") air-cooled four-cycle motorcycle engine that is commonly available? The largest I know of for sure is the Yamaha street bike that was painted like a vintage Norton -- I think it was a 500 cc. But I have a pretty good hunch there are some more common dirt bikes at 500 cc, and maybe more.

This is still at the brainstorming stage, but I might be interested in such an engine if I can pick it up cheap at a local motorcycle wrecker. (Or if you have one laying around!) This would be for a Burning Man "Mutant Vehicle" project; motorizing a Grand Piano. I want a thumper for the "bass" sound of it.

Never mind any fancy thousand-dollar engines. The piano was free, and that's my general operating mode.

 

[ramairws601]

you might try a Honda 400EX ATV engine, later years had reverse as well and they are all over the place.

 

[Elliot Naess]

Hadn't thought of that -- ATVs are probably more common than dirt cycles these days! Let's include ATVs in the inquiry. It is important that this engine is quite common, so I can find one, and cheap. (And get parts, if needed.)

 

[the_experience03]

Suzuki makes a 700 cc thumper quad engine. I dare you to try and pull one over with the rope.

 

[Elliot Naess]

Surely, a 700 cc thumper would have electric start?

 

[the_experience03]

It has electric start and batteryless electonic fuel rejection. The problem is that even though it doesn't need a battery to start and run you're still stuck because you need it to start unless you're the hulk. Maybe during the summer they wouldn't be so bad, but everything in Minnesota is rated based on its January-February performance. Even my '86 TRX350 can be a bear to kickstart which is why it has a high dollar AGM battery I tested out to 384cca. That would be another cool motor to look at (also found in the ATC350X) as it's 4 valve design makes if a pretty powerful engine given its size. It's also a sleeved engine which you can probably appreciate being a big truck guy. The best part is that big bore kits are widely available and the sleeve means no expensive machine work.

 

[Elliot Naess]

The idea is to install this engine under a Grand Piano, so the business of starting it is largely a matter of access. I'd rather start it with a key next to the piano keys, than crawl underneath the piano and kick start it while stooped over double!

350 cc would probably be plenty power, since it will be geared for a top speed of 5 MPH. But this is partly about sound, so I figured I'd shoot for 500-plus to start with.

Sorry about the Minnesota climate!
But in the Black Rock Desert in August, we worry more about overheating.

 

[Jarlaxle]

For really weird, some old British Enfield motorcycles were powered by a pushrod 500cc single-cylinder engine.

 

[Elliot Naess]

Oh yeah, I don't doubt the British built some mighty Thumpers back in the day! No balance shafts either, I bet!

As for the Honda 400 EX, I looked at completed listings on eBay and the cheapest one that sold recently was still over a thousand. And complete engines don't seem to appear at all; just parts. But now I know something I can start sniffing after.

 

[the_experience03]

I'm not sure that you're going to find the ATC350X/old TRX350 350 cc motor for real cheap, but it has a wonderful sound, especially if you ditch the 2-in-1 muffler as it has dual exhaust on it, but you're not going to get that really powerful thump if that's what you're looking for. It's more of a raucous sound that seems to want to rev just a little bit higher. I think just about anything with the spark arrestor and packing removed from the muffler is going to give that chest hitting sound, but a heavily oversquare engine is going to do a better job, especially with some compression behind it.

 

[Elliot Naess]

I don't want it loud. That's the piano's job. I want the engine inoffensive. And to my mind, "booof-booof-booof" is less annoying than "brrrrrrrrrrrrr".

That said, I'll take almost anything that I can get real cheap that will do the job. Options include golf cart and small automobile.

 

[Elliot Naess]

I've got a 10 horse B&S off of an old McCulloch generator...can't say it will sound nice though

My ears hurt just thinking the words "Briggs & Stratton".

But if you are serious about parting with it, we ought to discuss it -- price, location, and details of the engine for starters.

 

[SeanF-SKO]

Suzuki DR650 (air-cooled)
Honda XR650 (air-cooled)
Kawasaki KLR 650 (water-cooled)
Suzuki Savage is 650cc (air cooled)
Moto guzzi Falcone, Nuovo Falcone, and Super Alce are 500cc, air cooled. Due to vintage/Euro status, maybe not available cheap (but you never know).

IIRC all of these are carb'ed, if that matters.

 

[Elliot Naess]

Yeehah! Looks like those are the Big Guns I asked for! Now I'll spend a happy half hour poking around on the interweb learning about those.

 

[the_experience03]

Knowing now the expectations of this motor....

Toyota 22r

/thread

 

[Elliot Naess]

The 22R is like the SBC (Small Block Chevy) of small foreign cars, right? Even I knew that.

 

[spirit_of_76]

I had a late 80's XL600R Honda , plenty of power 100mph (on knobbys) 4valve hemi head ,primary and secondary carbs, and likely much cheaper than a 650, kick start only though. XR dirtbike I believe has the same engine also available in a 500

 

[the_experience03]

You could probably pick up an entire rusted out old 2wd Toyota truck for <$500 which would give you a 22R, transmission, and rear axle. Heck, you'd even have steering and brakes if you really wanted. They are incredibly easy to make so quiet all you hear are the solid cam followers clicking away.

 

[Elliot Naess]

And around here, that Toyota wouldn't even have a speck of rust on it! Nah-nah-nah-nah-naaaaaah!
(No offense intended.)

As for using an automobile, I'm thinking I would want it very small, like a Geo Metro. We want to hide the mechanical parts as much as possible. The original idea, and very popular at Burning Man for this purpose, is a golf cart.

But yeah, I'm learning about the thumpers. Most of those "Big Gun" 650s started out a bit smaller back in the 1980s, and that increases the odds of finding one cheap.

The Honda ATV is very interesting. And I could use the rear axle as an intermediate shaft to gear the thing down to Burning Man speed.

Sure appreciate all the information! Keep it coming!

 

[the_experience03]

A Toyota is going to have a 3.92 first gear, 2.28 low range in the t-case if you get a 4wd, and 4.10's in the diff most likely. With small passenger car tires on the stock 15x6JJ rims I think you'd be hard pressed to go too fast.