Saturday, May 17, 2008

Rear Break - Done

And it works too!

Just need to machine a spacer for the break plate so it fits onto the axle I plan on using.  Sadly it will not work with my rigid frame, the upper brace contacts the bracket and there is not enough clearance for both. I could probably make it work with a little grinding to my frame but I like my rigid frame more than I like the idea of having a rear disk break.

Build info - I chose a bicycle disk and caliper for the rear wheel, I ended up running a cable type break vs a hydraulic system just because it will be easier and I have a larger option when it comes to lever choices. I started the process by removing the ribs on the pedal side of the hub on the lathe. I also faced the hub so the side will be perfectly aligned with the wheel. the original bolt spacing for the disk was too small to clear the hub, I put it on the lathe and removed the offending parts. Then I brought the disk over to the vertical mill and set it up on the indexing head (a device that allows very precise 1/2° rotations of the object clamped into it) to drill 6 new mounting holes 60° apart in the disk. I then drilled 6 identically positioned holes into the hub, then tapped said holes. The disk is bolted to the hub with spacers to allow the caliper to clear the wheel.

Wednesday, April 16, 2008

Back in the Saddle Again

It has been awhile hasn't it?
Been lazy recently and have not made much progress. 

Been in the process of moving, now I have a new garage in South SF that is much bigger. 
Finally have a good work bench and some real tool storage as well. I have some more shelving along the left wall now (and less shit on the ground) to hold the rest of my parts. The garage is 20x25 with a 15ft celling, have of the space is mine. 

But I bet you just care about my progress with the bike.

 I had finished the milling of the motor mount for clearance last time I posted. I finally got around to marking and drilling the mount holes for the motor. The holes were pretty close to perfect, a little massaging and the bolts slid right in. There is a lot of metal on the upper part of the mount because I was unsure of the finial angle of the motor and how low it needed to sit. Now that I have the motor in the frame it looks like it is only going to hang a few inches lower than a stock puch motor. Still need to mark the cut line on the mount and machine round groves into the mount that match the profile of the frame.

Also notice that the intake that was last seen in pieces has been welded together (thanks Zeke) and is as perfect as I could have hoped.

Thursday, December 20, 2007


I have never had a speedometer or any other instruments on a moped before. I decided that should be changed for this build. I wanted to be able to see speed rpm and water temp. I was going to build a dash and mount the tiny tach and the gps speedo I have and then go out and get a water temp meter. I decided that this thing would be a much more elegant solution and the price was right.

Wednesday, December 19, 2007


Sorry no photos...

Just a bit of good news!. I just for off the phone with the DMV, I was tyring to research the magnum. The person I purchased it from removed the pedals and welded some pegs onto the swingarm. Doing this the bike was no longer legally a moped, he actually went out and registered it as a motorcycle back in '94.

Since then California laws have changed regarding registering two strokes for road use. It is next to impossibly to do so. Even if you found a way you would need to bike to be signed off for road use by the CHP and the DMV (another difficult task).

The bike is still in there system, registered to the old owner and will cost me $54 to bring the registration current. I have the title and a bill of sale so I just need to go down to the DMV in person and I will have one Puch Magnum motorcycle titled in my name.

No hassle, no inspection & no more worries about driving a bike that is not legal for road use.

Thursday, December 13, 2007


Yea it's a manual 6 speed, So?
The motor weighs in at about 30lbs, just a bit heavier than a 2 speed puch engine. But it puts out about twice the power and had 4 extra gears to choose from. It was originally in my RS50 till I had a head gasket failure. The end result of the head gasket going south was my crankcase got filled to the brim with coolant. You need to tear the motor down to pieces to get to the crank so that's what happened. This also gave me an opportunity to put a new racing crank and high end bearing into the thing. Thanks AJ for the crank and a big thumbs up to you and Marcus for helping me get the thing back together. I shoved the motor into my rs frame to test how it ran, started right up and it sounded like a champ. 

Not much will be done to the motor, all it needs is a chassis to make it happy. I just wish I had a motor to put into the rs now so I could teach Jessica how to ride. That's for another time and another blog *cough* CRF250r *cough*.

Motor Mount

This is currently my main focus. It is the main component of the bike since everything else is centered around it. I was going to use plate steel and have Brian weld the shit together, I talked it through with him and he suggested square tube stock. I looked into it and everything came together perfectly. The withe of the motor mounts is 3.1" and I found some 3/16" thick 3 1/2 inch square tube. That means that the Inside diameter of the tube is like 3.15" the motor just barley fits in SCORE! 

I took the foot long piece of tube to machine shop class and cut out about 7" on one of the 4 walls. This gives me a place for the rear 2 mounts to attach to. no I need to cut some reliefs to accommodate the round section on the rear of the motor. 

Next step is to cut 3/16 of an inch of either side of the motor mounts on the case. Then I need to make some shims that will allow me to shift the motor left or right to make sure the chain line (path between the front and rear sprockets is perfect). 


I was planning on just using the magnum swing-arm with a mount welded to it for the bike shock. I was going to build a trellis to reinforce the lower section of the swing-arm. 

Since the bike shock is out of the picture and I am building a custom motor mount... 
I guess I am making a swing-arm too. 

I like the tube look of the magnum swing-arm so I want to keep that look. I will add to it and take a page from Ducati and incorporate a trellis into the swingarm to make sure it is nice and strong. 
The main part of the swing-arm will be made out of 1 1/4" .120 wall tube and the lower part of the swing-arm will be made of 3/4" .120 tube. I wanted to make sure it was strong but not make it look bulky. The swing-arm will be mounted through bearings so make it solid and pivot smooth. The trellis section will angle off the swing-arm mounts and meet the other angle of the trellis at the mount for the shock. This will create a nice strong triangle and I will build in a few more smaller triangles as well. 

I will be building motorcycle type chain adjusters and having them welded to the tube swing-arm. These will allow me to use a through type axle that is not actually attached to the wheel. Since I will be using sealed bearings on the axle this will work out fine.

I need to finish the motor mount and get it welded to the frame before I can start work on the swing-arm. Most of the measurements on the swing-arm will be derived after the motor mount is set.