The 2 the Max Project

[hodakamax]

Yikes, More minor problems. All the rear linkages are filling up all the available spaces for brake brace, levers and rods, heim joints and associated fasteners along with rear brake plate lever and brace. One of the last things to fit is the exhaust pipe and it has been off and on several times. It seems to have grown somehow. There's been several changes in layout to make things fit as you go and clearance for the exhaust is diminishing to a close call. I finally had to fabricate an aluminum 1/4" spacer to move the foot peg out which seems to have solved the problem. Now I think I can figure out the pipe mount to frame. Whew, close call so to speak.

Maxie

[Bill2001]

First thought off the top o'th head is to shorten the levers on the brake pedal and the outer intermediate lever. That might give a little extra wiggle room. Are the lever ratios sacred? Have they beem thrashed to death or are they just the first guess? I'd be inclined to keep the "stock" Hodaka ratio since it seems to work well.

Would it disrupt the hydrodynamics of the exhaust flow to put a small ding in the expansion pipe cone under the intermediate lever for clearance?

Looks good.

[Hydraulic Jack]

First observation: Shortening the levers will reduce brake authority requiring heavier pressures to activate brakes. If assembly is light to start with, increasing the required force to activate the brakes isn't a good idea.

Second observation: While everything inside an expansion chamber has an effect of how it works, small dings rarely change anything you can feel, and some race guys used to deliberately ding their chambers to "tune" them to preference. There is as far as I know no science to back up the notion that you can tune a pipe with a hammer, but there is lots of real world experience with rock dings that don't stop a race.

So I would seriously consider either standing off the exhaust pipe to create space, or placing appropriate dings in the pipe as needed to create clearance, or both, rather than spacing off the brake assembly which is already soft enough without more leverage in the wrong place. Frankly, lowering the exhaust pipe should be easy to do.

[hodakamax]

Hey Bill and Jack, thanks for your input. When you tighten the screw on exhaust nut to the cylinder you have to twist the pipe around that axis. Rotating the pipe toward you is up and out at the back. Confusing huh? Anyway, I've got the exhaust nut tight on the cylinder and rotated it to clear everything. A change of a few fasteners with shorter heads and shortening the castle nut/bolt on the rear brake plate arm along with spacing the foot pegs out 1/4" and all is clearing properly. I've pinned everything down with clamps in preparation for the pipe mount to frame bracket. The bracket also is adjustable with washers to fine tune the clearances. All appears to be well.

Maxie

[Bill2001]

Good, things aligned well enough through tinkering. I have found tgat the best way to mount the early collar-type of cylinder attachment is to slightly snug the attachment collar and successively adjust the mid- and end-point frame mounts. The idea is to mount it as stress-free as possible. And of course you know it is a good idea to drill the exhaust collar for safety wire and wire it to a cylinder fin to keep it snug.

Have you evaluated the maximum-lean muff-to-ground clearance yet? That will be hard to check until you get tires and suspension underneath.

It'd be a shame if this turned out to lean like a Harley Bagger...

[hodakamax]

Hey Bill. Good question. I'd already done the lean science on the pegs when figuring out peg height. The bike should contact the pegs at at about 30 degrees, about the time the handlebars do. Way farther than the tires and Max could lean. The pipe would still clear. The pipe is an aftermarket flat track pipe of the times and really does fit in tight all the way back.

Hmm, this is really hard to measure without tires and hanging on straps with a loose pipe. Tires should be on soon and pipe mounted securely where I can just tip it over. Stay tuned for the easy way.

Maxie

[Bill2001]

The pipe does tuck in real nice, but the high point where the two cones meet caught my eye. Get wheels and tires on it'll be easy to check.

[hodakamax]

Grrrr, this pipe bracket is eating my lunch. I've been banging on this curved bracket for over an hour. The position is critical for the pipe to clear all the linkage and such. One more mount and mark and I'm off to the welder to tack this thing in place. Tack, check and weld. It's also time to weld the pivot shaft assembly together and see how this all fits.

Max

[Hydraulic Jack]

Regarding the goober welds on the steering head, I would be tempted to remove the gussets completely, clean the frame tubes, and start over.

As for the expansion chamber fitment, if you find a combination that makes the whole body of the pipe work with the rest of the assembly but leaves the head pipe slightly cocked, you can wiggle in the head pipe with a torch. Cherry up a section of head pipe in a convenient spot and tweak and tighten the collar nut. The difference in alignment should be very slight anyway, and should be easy enough to correct. Easier at any rate than trying to move, ding, stand off, and rebracket the rest of the pipe.

[hodakamax]

I just returned from Rod Blackburn's Hot Rod Shop where he dropped everything and welded up the pivot arm along with tacking on the pipe bracket. Wow, what a resource that guy is. Check those teeny welds! I did replace the 1/4 shaft with some tough stuff courtesy of my engineer friend. Now I can put all this together and check all the clearances before some serious grinding,welding and blasting on the frame.

One of zillions of reports---

Maxie

[hodakamax]

A bolt together test and all is well. Really close I must say.

Max

[Bill2001]

Ach, ya. Als the Chermins would say, "gutentight".

[hodakamax]

The Dremel has logged some time the last two days as has almost all brass brushes and anything related to wheel polishing including me. Not show quality but better by orders of magnitude and quite acceptable for the project. This has been holding up the tire mounting for awhile. The tires are Avon AV83 rated S for a maximum speed of 112 MPH which should cover the road race version. Front size is 2.75 x 18 and rear 3.00 x 18. I'm finding that these are difficult sizes to find and can be expensive. The Avons helped the budget with total tire bill less than $150 with tubes, rim strips and shipping.

I must say that it does look better hanging around the shop with shiny wheels and real tires, more motorcycle like. At least some of the complicated mechanical work has been prototyped and I can get on with on with some structural repairs. I'm getting close to the initial blasting for repairs and other welding which is always a good visual thing after weeks of rust, paint remnants and grind marks.

Just as I was on a roll my wife tells me that company is coming for the weekend and that I should act responsible for a few days by helping her prep the house. I do have a few messes going. Whatever.

Reporting,

Max

[Makotosun]

Looking SWEET!

[Bill2001]

Nice!!

Wheels are a benchmark. Now you can sit on the bike and make vrooom vrooomm pretend-noises.

[hodakamax]

Hey thanks Gary! Encouragement keeps this project going!

And Bill. Yes! Varoom sounds already made!

Maxie

[Bullfrog]

Very nice craftsmanship on the brake pivot rod/arm assembly! It is just so amazing how installing the wheels and tires increases the pulse rate! Glad to hear that engine noises have already been er, um, voiced . . . heck I did a little "rrrrrriiiiiiinnnnNNNNNGGGGG-ding-ding" right here in front of the computer!
Ed

[matt glascock]

[hodakamax]

Giggle giggle. It's good to know that we're all still kids at heart!

Maxie

[matt glascock]

I think we're all still just kids period. Evidence you ask? Talk to my wife.

[Bill2001]

Ah! "Ring-a-ding". I was trying to remember the proper 2-stroke phonics. All I could do was "Zun, Zun, dap-dap-dap" but thought that'd be a bit obscure.

Bikes are fun. Every kid needs a bike.

[hodakamax]

I thought I'd better give an interesting engineering report after assembling and testing the rear brake assembly. During testing the foot lever effectively stops the wheel but with some pivot shaft deflection noticeable. How can that be was my first thought. Hmm (I always say that when baffled). A quick test of braking with my hand on the shaft between the support bearings reveals that the shaft is bowing between the two bearings. I never realized during all this design that the bearings also gimbal and quite a bit. I guess that's what prototyping is all about.

Actually the braking system works quite well but obviously a bigger shaft or tube would be a better design. The next up bearing replacement that would have the same bolt-in design would allow for a 12mm shaft or tube. The existing 1/4" shaft is about 6mm for comparison. A solid steel shaft would weigh about 1/3 # and a tube would probably suffice. One option would be 12mm stainless with 2mm wall thickness which could then have stainless steel arms that could polish up nicely. Another option could be an aluminum shaft and 1/4" aluminum levers. All things not pressing or design changing and requiring minimum effort to build a new shaft and replacing two bearings for a better design.

Well, that's the engineering report for now and a couple of pix.

Max

[Hydraulic Jack]

The obvious place to support your pivot assembly is between the two opposed levers on the welded shaft, directly over the frame tube. You could leave one of your bearings in place, eliminate the second bearing and any connecting shaft between the two bearings. Quarter inch stub would be enough, so the first bearing can remain the 1/4" you have. Leave enough shaft beyond the bearing for a collar much like the one you have in front of the bearing. This will keep the shaft from traveling along the axis.

The support could be a split block. A welded saddle on the frame, a removable upper piece, and a split block of something along the lines of Delrin, Nylon, or Teflon, and two cap screws to retain the upper half of the saddle. The block will support whatever thrust is generated in the assembly, and the plastic will be sufficiently slippery that a precision bearing isn't needed in that spot. You won't have to disassemble the levers or abandon any of the precision work so far. The whole thing will weigh far less than a half a foot of steel rod, and you will loose the weight of one of the bearings.

Of course this might require careful and somewhat precise manufacturing of small parts, but you already have that covered.

[Hydraulic Jack]

This Image is intended only to give the general idea of what a split pillow looks like.

[Bullfrog]

Custom "block" production in Delrin or UHMW is also still available.
Ed