Tiny Roots Blower for "Tiddler" motorcycles

[Jack Gifford]

hypocycloidal: describes the path taken by a point on a circle as the circle rolls around the inside of a larger circle (coplanar).
epicycloidal: describes the path taken by a point on a circle as the circle rolls around the outside of a smaller circle (coplanar).

Consider a planetary (aka 'epicyclic') gearset. It seems obvious that either term describes the path taken by a tooth of a planet gear. So that explains the 'epicyclic' nomenclature; but why is the redundant term 'hypocyclic' needed?

[Interested Observer]

The planetary gearset analogy is somewhat tricky.  It depends on your frame of reference.  The planet gear can only “roll on” one or the other of the reference sun or ring gears at a time.  If the sun gear is fixed, it produces the epicycloidal path on the outside of the gear.  If the ring gear is fixed the hypocycloidal path is generated on the inside of the gear, which is an entirely different path relative to the reference frame.

[Jack Gifford]

It sure appears to me that there is only one planet gear path, whether ring gear or sun gear is fixed.

[Dead Roman]

"In 2004, a fellow by the name of Fritz Kott set an AMA record at Bonneville on his 750cc flathead Harley using this very same pump."

" I raced a blown Honda S-90 in the seventies for 2 years with the same smog pump (blower) at Bonneville. I worked for Porsche & VW then & these little blowers came to the U.S. on ’68 or ’69 912 Porsches as a smog pump. I wondered then why a U.S. made pump came from Germany on a new Porsche 912 but looking back it was probably a stop-gap measure to make the car meet tightening smog laws. They were driven at about 2:1 with a vee belt on the 912’s and they didn’t live too long (20-30k miles) spinning up to about 12k rpm. What happened was the bearings in the gears ran out of oil and it seized up and broke the belt. It is just a small roots blower with straight steel lobes and sealed bearings at one end. We threw a lot of them away and most owners didn’t put them back on in the Midwest. They didn’t appear to be something you could rebuild. You should be able to find one at some small old Porsche shops.

On the S-90 I drove it with a small chain on the generator side at about 1:1, and that was too much boost. It would make 20psi very quickly. Trying to supercharge a single-cylinder small motor is very difficult. It becomes a rhythmic, surging, pulsing, tuning nightmare. I tried blow-through, draw-through, long manifolds, very long manifolds, short ones, and all kinds of plenums. The surge was very violent. It accelerated like a 350cc, really pulling hard, and the next second it would shut off – about throwing you over the handlebars. It felt like the carb quit flowing air momentarily. We finally got it reasonable by making a plenum out of ½ of a propane torch cylinder with Homelite pyramid reed valves on each end to keep the charge going in the right direction. There was another guy from (I think) Riverside CA. doing the same thing and I think his name was Fletcher Izzard, also with an S-90.
I had no problems at all with the blower. I would say it’s not going to pressurize much more than a 200cc 4 stroke motor because it can’t flow enough volume of air. I ported mine a little bit.
The man that rode my bike was Mike McCann (Lisbon IA) who is the man with the large white sun block on his nose pushing Burt Munroe off the line in the out-takes of The World’s Fastest Indian movie. I then was the young guy hanging out at the old Chevy garage in Wendover during Speed Week listening to all these old guys, Burt, Mike, Rollie Free, and others drinking beer and bench racing - telling tall stories. It doesn’t get any better than that!
Bvilletom
Tom Bruch

Some info I found on another site.

So it says a guy set a record on a 750 4-stroke using this blower and then goes on to say it wouldnt work on anything over a 400??

[Dean Los Angeles]

So it says a guy set a record on a 750 4-stroke using this blower and then goes on to say it wouldnt work on anything over a 400??

I guy running a Harley set cherry picked a record in the 70's by taking the heater blower out of his truck to run the "blown" category.

That's why the rule now says "engine or exhaust driven". That doesn't mean it has to really do anything. If you can't be competitive in the normally aspirated class, stick a blower on it an run an open or lower record class.
Case in point in the 1000cc class.
M-PF    Full House Mouse 2    H/D    08/03    150.150
M-PBF    Dave Arnold    H/D    08/11    125.922

Those two records exist because we made a pushrod class so the lame ducks could set a record.
These are the competitive speeds
M-F    Scott Guthrie Racing    Yamaha    08/04    197.702
M-BF    Ryan Keep    Suzuki    08/10    208.652

Dont' forget the wheel on a stick so that your pushrod can be even more lame duck.
SC-PF    Willie Buchta    Buell    10/07    128.136
SC-F    Walter Kohler    Suzuki    10/07    168.566 (faster, but still 30mph slower than Guthrie's record)

[Stan Back]

Check the Bonneville record lists.

Whole lot more 500cc records than 350cc or 175cc records, but same classes available.
Be interesting if someone had the time to calculate whether there a just hundreds or maybe thousands of "unset" records.

Hope this information doesn't fall into the hands of those that list every record they have with every post.  Sure could lead to a lot of scrolling to read the actual posts.

Stan Back

[Seldom Seen Slim]

I do remember Fritz running a blower of some type on a bike, and think that he allowed as to how the blower was sorta there for looks (read:  to get into the blown class) vs. to provide some pressure to the intake side.  Fritz has gone to Impound in the sky now and can't verify nor deny the story, but don't I also remember that soon after this event -- the rules got amended to require that a to qualify for a blown class (in bikes, at least) the blower had to demonstrably provide in increase in intake tract pressure?

By the way -- if you don't remember Fritz -- he does have a bit part in World's Fastest Indian so you can get a glimpse of the guy.  I remember it well -- Nancy and I were watching the film in a theater (we don't go to movies often at all) and I saw him and shouted out "Hey -- there's Fritz Kott!!".  Nancy elbowed me vigorously to shut me up.  Not used to seeing folks I know in movies, I guess.

[Stan Back]

Fritz was a revered Roadster racer, too.  At El Mirage, he fielded (yes, a pun on words) the "World's Most Raced Roadster" (pickup).  I don't know who kept track, but I'm certain he was the current champ at the time.  Great guy, great family.

[saltwheels262]

great guy, that's for sure.

did not know him that well, but do miss him.

[Jack Gifford]

It sure appears to me that there is only one planet gear path, whether ring gear or sun gear is fixed...

Okay, I'm red-faced; embarassed; all of that. As 'Interested' said, it does truly depend on the frame of reference. I had to view epicycloid and hypocycloid traces to get that through my thick skull.