Havasu Dave's - "Mini Bike" - (Just For Fun)

Dave mentioned Rube Goldberg in post #314, He was an inventor who designed contraptions to complicate simple tasks. Google him sometime, the guy was a genius, and comical like Havasu Dave.
Hello fans! No, I am not sand bagging on the video, or this project. Two days ago, I went out to start the bike for a video shoot. I ended up blowing a bunch of blue smoke out of the carburetor. Now I know what you are thinking:

Flywheel key. (Checked)
Timing. (Checked)
Spark under compression. (Checked)
Plug. (Replaced)
Reeds. (Inspected, no problems found, replaced anyway)
Carburetor. (Disassembled, inspected, no problems found, spare carb installed, no help)

Both Louie and Vince, (they're kart guys and West Bend savvy guys) said I was probably losing crank case pressure. I didn't find anything wrong, UNTIL I removed the clutch because I was taking the whole damn thing apart!

What did I find? The PTO seal hanging off of the crankshaft behind the clutch. Yes, when I installed it, I misaligned it, (crankshaft was in) and bent it enough to "look" okay, but it was not. So yes indeed, as we like to say in the Great White North, "I blew a seal."

Down, but not out! What a tremendous learning experience this has been! :laugh:


Well-Known Member
Take 3 steps forward and 2 steps back. It's unfortunate but it's coming along real nice. Sorry for setbacks, that's really gonna be a sweet bike :thumbsup:
DAM...I hate it when that happens and you have to chase gremlins !:censure::censure: But glad you found it Dave .
I stumbled on it. Finding absolutely nothing wrong anywhere, I'd decided to take it all apart. Step one: Remove clutch. LOL, and there is was, bigger than life, just laying there.

That sucks Dave :doah: How soon can you get a new one :shrug:
I've got a new one coming Randy. Thing is, I just found out that this was a recognized problem with these engines, so an after market reducer and seal was made. So hopefully Vince will be sending me the improved version, and I can get this pig back on the road!

Take 3 steps forward and 2 steps back. It's unfortunate but it's coming along real nice. Sorry for setbacks, that's really gonna be a sweet bike :thumbsup:
Thanks, and it's okay to take the steps back. I made the choice of building (and learning) about this engine, and despite the frustration from time to time, it is rewarding to do it myself- as painfully slow the learning curve is sometimes.
A slow day, waiting for parts, so I'll back track a little bit. This is the Max-Torque clutch I use on this bike. I have to run it with sprocket outboard. I got it four years ago for this engine and it has some hours on it. Note that a total of four fiber washers are used during installation. This is to set up spacing between the clutch inner and outer portions, as well as the total space the clutch takes on the 9/16" PTO shaft. One more fiber washer, and the PTO nut will torque the clutch. One less, and there will be slop, and the clutch will hit the engine mount bolts.

Using this type of mount required countersinking the 1/4-20 bolts. There is just no clearance here once the mount sucks it up. Yes, that bearing is where the seal used to be, and what I am waiting for now. Note top 5/16 holes are for clutch guard, because a standard PTO mounted guard will obviously not fit.

No one past, or present makes a clutch guard for this application, so I had to make my own. I made the mount section first, then dollied it around a round anvil (an old Cat brake) to get the lip. After bending the guard portion, I welded it together. It works beautifully, but it took me two tries to get it looking decent.

This is the 4 inch brake drum. I used a 3/4 to 5/8 adapter hub and oversized keyway off of ebay. The key was not staying in place, so I used Loctite 620 (the green stuff) and it stays now! This is the only way the brake will fit and work. Note how loose the band fits. This is so I don't have to use an ugly spring to keep the band spread to prevent binding. The pivot shaft opposite the lock nut contains a compression spring, which compensates for the wow and flutter. This brake easily locks up the rear wheel.

The Tilly Clone carburetor. It is machined better than the Tilly. One inch bore, way bigger than the stock 189E. Fuel feed is on the bottom. It doesn't leak much, if at all. I had to clock it this way to have access to the High and Low Speed needle jets. Gem velocity stack, copy of a V Power manifold and stuffer, as well as WB 820 V4 reed cage.

EC Carburetors' throttle mount. With the roller bearing on the handle bars, and this set up, it is the smoothest, most easily adjustable throttle I have ever had the pleasure of not messing with!

An embarrassing view of my engine mounting job. The cross piece was first welded to the frame, square, then the mounts welded on. I had to do all of this with the engine mounted to the pieces. I am lucky it came out "this" good. It is not as strong as I'd like to be, but adequate for this engine.

A view from the real pleather snake skin seat along the tank. Doing up the bungs was just scary. After both holes were drilled, the top frame consisted of about 1/8" of metal holding it together. The Gerald LSCustoms tank sits on two rubber grommets and is very stable like this.

Another view of the tank mount. The tank doesn't look "this" scratched up in real life. The tank mount bungs are as low as I could go.



Active Member
Even after hearing all the issues with the WB, I still want one! I'm learning a lot from what you've posted. Thanks Dave! Hope you get your seal soon!
Even after hearing all the issues with the WB, I still want one! I'm learning a lot from what you've posted. Thanks Dave! Hope you get your seal soon!
What I am waiting for is an after market spacer that works with a different, smaller, seal to eliminate the blow out problem. I wouldn't say I have had a lot of problems per se with this engine. I tend to document everything, and not gloss over build challenges, so perhaps the appearance is more dire than the reality. Not to mention the learning curve.

I am happy that at least one person can benefit from what I've detailed, so thank you for mentioning it.
Left is original PTO seal, part number 31146. On the right is the PTO insert with the 2770146-1 seal, which is the same seal used on the support plate, or "magneto side." Insert is machined down to fit PTO seal pinning. (punched)

Seal pressed into insert, insert installed, all with "Perma-Tex" gasket shellac. Note divot alignment. Insert seats on to PTO bearing.

Ya Baby! That took me back almost fifty years to to the kart races! I hope your neighbors like hot little two-strokes. If they don't, they should learn to! Good video, Dave.