Edition 3
Edition 1 | Edition 2 | Edition 4

In Build a Bike Edition 2, we extended and winged our oil bag, mounted and centered our 250 rear tire and wheel, and edged our rear fender. In this issue we'll fabricate a top frame plate that will serve as the main mounting point for our 11" wide rear fender, and the base that our seat pan will sit down into.

We're also going to mount our gas tank, pan in the lower tank and frame under the seat post which is a simple trick that really cleans up the bottom of a gas tank. While we're working around the tank area we'll gusset the steering neck area of the frame where we cut out the ugly horizontal support tube in the last issue.

I'm stepping up the pace as Fall and the cooler weather sets in, I don't mind working longer hours in the garage now that it's cooled down, and I've made up my mind to have the bike done, painted and assembled for the final time by late January, so I'm shiftin into over drive!

I'm sure you've noticed by now that I haven't installed my 121" TP motor yet.

While I'm doing fabrication work, welding, grinding and cutting I don't like getting slag or metal grindings on my new motor so I use a mock up lower case to bolt up the primary backing plate to line up the motor and transmission.

With the motor and transmission in line I can then line up the transmission pulley with the rear pulley to make sure everything runs true. Now that I have the motor, transmission and rear pulley lined up correctly I can determine where to notch out the rear fender to accommodate the rear belt.

In photo #1 I've got the fender marked where it needs to be notched to accommodate the belt by using a 1 " piece of iron strap to simulate the belt passing thru the fender from the rear pulley to the transmission pulley.

Using the 1 " strap again, from the bottom of the rear pulley to the bottom of the transmission pulley I mark the lower cut out for the belt.

In photo #2 I've removed the rear fender and am using the saber saw to cut the passage for the rear belt.

After cutting the rear fender I'll re-mount the fender and using the iron strap in place of the belt. I'll double check to make certain I've allowed for sufficient belt clearance.

After a little trimming, just to be sure, I'll take a 1/8" iron rod and form it and weld it around the edge of the belt cut out in the fender. Afterwards I'll grind the welds down smooth and radius them to the contour of the rod.

This takes a little time but I like doing it because it provides additional strength, helps to prevent the fender from fatigue cracking around the cut out and most importantly, it gives it a custom look that separates it from most custom bikes.

Photo's #3 and #4.1 show the finished belt cut-outs with the rear belt installed and adjusted. Later when we mold the frame, we'll run a little filler around the beading on the belt cut-outs for the final finish.

Now it's time to start fabricating the top plate for the frame, which we'll construct out of 3/16" plate steel.

I want to weld the rear fender into the top plate we're making, so ultimately the frame, rear fender and seat base will look like the are part of the frame itself.

To get the proper clearance between the rear fender and rear tire and pushing for that low, " fender molded to the tire" look, we're going to tape a 3/8" black heater hose to the very center of the tire and set the fender on the hose. Giving us a 3/8" clearance between our rear tire and fender.

Now once again using poster board as a template, I tape the poster board to the top of the frame around the seat, rear fender area, and trace the frame outline onto the poster board. After I have carefully trimmed the poster board template to "fit exactly", the key word being "exactly", which is not the same as "pretty close."

I'll transfer the poster board template onto a " piece of plywood, and using a plasma cutter, I'll cut the plywood pattern out of the 3/16" plate steel.

I've also made templates for rear fender struts that I'll cut out of the same plate steel. Photo's #5 and #6 are cutting around the patterns with the plasma cutter.

After cutting the patterns out of the 3/16" plate I'll take a grinder and grind around the edge of the pieces making the edges smooth and fitting them continually to the frame so that ultimately the final fit is like photo's # 7 and #8.

If your templates fit "exactly" and the pieces you made from your templates were cut accurately, They should fit nicely, like these.

While cutting out the top plate, I also cut out and trimmed the fender struts which will be welded onto the top plate behind the fender.

Finally the fender struts will be welded to the fender, making the frame fender and struts one piece.

Photo #9 shows the trimmed fender struts.

Photo's #10 and #11 show the struts being set into place prior to being welded in.

Now that the fender and top plate are cut and fit, I'll clamp all the pieces into place and re-check to make certain that nothing has shifted from place.

In photo # 12, I'll begin to tack weld everything into place and stop to check. I check after I've tack welded my work to make sure everything is still where it belongs, before I weld it in solid.


Photo's #13 and #14 show the top plate after spending considerable time grinding the welds and making the top plate radius into the frame.

Now we're going to fit our new 63.5mm inverted chrome Spyke front forks with our Eddie Trotta 6 degree raked trees.

Photo's #15 and #16 show the assembly process which was pretty simple due to the quality of the components.

I like to coat my upper fork legs with Vaseline before I slip them thru the trees, it helps to prevent scratching the tubes. This front end is 12" over stock.

Look at photo's #15 and #16 and look at the bottom of the tank and the open tunnel.

I want to clean up this area by fabricating a "pan" or "plate" that is about 3/16" narrower than the tunnel and welded to the frame so when the tank sits down onto the mounts, ( 4 recessed mounts on the tank bottom) it looks like a flat bottom, with no tunnel.

Photo #17 shows the templates being made




Photo # 18 shows the tunnel partially plated at the front of the tank.


Photo#19 shows the plating all the way back to the seat post, oil tank area.

This will cover all the "clutter" you see when you look up at the under side of your tank. With a 5" stretch in the down tube and 3" more in the backbone the bottom of the tank will be very visible.

Edition 1 | Edition 2 | Edition 4