saving a 75 now with pictures

[srust58]

Pulled the exhaust system off and gave it a quick polishing. It is in decent shape, good enough for my needs but hardly restoration quality. The right muffler has a dent in the side/bottom (shown at the top) and there are a few rust spots but they are solid with no holes or weak spots. In the right one the end cap on the baffle about 1 foot inside the muffler is 80% gone making it a straight shot through but the rest of the baffle is there. On the left this cap is about 80% there. I was wondering why it was louder on the right when I fired it up.

[srust58]

I had a loose faceplate in the speedo as a screw had backed out. I used a paint can opener to pry open the bezel. It is the perfect tool for lifting up the crimped down portion of the metal ring. On the first pass just lift it part way and then make a few more passes around the ring to lift it enough to get the bezel off. I just used a large flat blade screwdriver to bend it back down. I did not know if my speedo was functional so I used a cordless drill to test it prior to putting it back together. My ancient 9v Makita could only mange 30 mph. ;D The tach is lazy so next I need to investigate that.

[srust58]

I rebuilt the caliper. There is not enough clearance to get the pistons out so the caliper has to be split. The catch is once split you can't develop the pressure to get the pistons out. So I took it apart and swung one side 180 degrees and bolted it back together. Using a c clamp to hold one side in place I forced the other piston out and rebuilt that side and then repeated the process for the other. With the caliper in that position it was difficult to get it properly bled but I was able to get it good enough for it to work the piston out. The pistons were in much better shape than I thought with only 2 pits on each one that I filled with JB Weld. They were near the top edge so were probably not an issue. I used a sharp razor to shave down the filler to get it smooth. It is very important to clean out the two grooves the seals sit in. Junk builds up in there and is one cause of sticking pads that don't retract.

[srust58]

I opened up the tach the other day as it was not very responsive and would hang up below 2000rpm. I did not really have a clue on how these work but after seeing it open it is quite a simple device. The input shaft coming from the cable end passes through a bearing and has a magnet attached to the other end. As the magnet spins it turns a bowl shaped piece shrouding the magnet that is attached to the needle. There is no physical connection. This bowl shaped piece also has a watch spring attached that loads up as the bowl turns. It acts to pull the needle back down when you let off the throttle and may also have something to do with calibrating the tach. In the second picture I have removed a piece that shrouds the bottom half of the bowl and here is where the problem was. A clear jelly like lubricant had collected here and was slowing the rotation of the bowl in both directions. Maybe the stuff had thickened with age. The magnet is more visible in this picture also ( the dark round object) Anyway I cleaned it out and the tach is responsive and no longer hangs up at low rpm.

Once the bezel is pried off the two screws on the back on either side of the cable connection are all that hold the mechanism in place.

[wideload]

I look for your next post every time I log in. I take advantage of the info you post quite frequently. Great pics and even better text. Technical writer?

[srust58]

Nov 13, 2009 21:41:04 GMT -5 wideload said:

I look for your next post every time I log in. I take advantage of the info you post quite frequently. Great pics and even better text. Technical writer?

No, but I just try write a good description of what I am doing. Glad you are able to find something useful. I am learning a bit also even though I have owned my 79 for so long it has been so reliable I have never had to do any real repairs. When I picked up the Honda 750 that had been stored for 25 years the biggest issue was rebuilding the disc brake system and cleaning the tank. So this 75 is the deepest I have ever torn into a bike.

I see you have a 74. I don't see them that often. I know they are almost identical to the 75.

[wideload]

My son and I are working on his recently acquired '76. I am thinking the brake system is very similar to your 75 - what do you make of those 1/2 diameter shims on the back of the stock disc pads? Neither of us paid attention to the original orientation. Now that we installed new pads, we are wondering if the shims are meant to be on the forward side of the disc, or the rearward side. Thoughts?

[srust58]

This is a photo of one of my pads with the shim. It was just thin stainless steel and the small half circle tab fits into a hole on the backside of the pad. The arrow points down and forward. The shim is between the pad and the piston and on the lower half of the pad. To me it seems they are meant to keep the pad from rattling. Yours sounds different. With only 10K on this bike I am guessing this is the stock shim and pad. I just cleaned it up and painted the backside.
My Honda has a thin plastic ring maybe an inch in diameter between the piston and pad but it is not used on all models and years.

[srust58]

I pulled the air boxes off as they had some surface corrosion so I cleaned and repainted them. Found a pair off really nice shocks off a low mileage bike. They are spotless with no corrosion. The lever on the headlight dimmer switch was broken so I found an entire left hand assembly for $9.00 from a 76 and swapped out the internal switch.

[xsleo]

wideload, the arrow on the shim points toward the front. The shims helps keep the pads parallel to the rotors. As the rotor rotates forward the pads tend to spread out at the front. The shims conteract this tendency.

[srust58]

Project back on track after a long delay. Got the whole bike home from a friends garage and decided a total frame tear down was in order.

Engine stand made from junk lying around the basement


stripped the frame and primed with two part epoxy primer. The tank and side covers are for my 79 XS. The helmet is my new lid...an authentic WW1 M1916 Imperial German Army helmet.


used a pipe clamp to press in new swing arm bushings.




Got delayed again and winter arrived so no paint spraying. I used Por 15 Hardnose and applied it with a brush. Worked out in the porch with a heater going. The stuff really stinks but goes on nice.

[srust58]

The rear wheel was in tough shape so with a bit of sanding. polishing, and new spokes...


I had this


Front rim was not as bad and took half the time to get it looking good. new spokes too.



made this low buck stand to true the wheels. It worked good and the wood dowels would give a little squeal when in light contact so it's just a matter of getting a nice even squeal all around.

[srust58]

Had trouble trying to put in tapered bearings...the bottom race went in cockeyed and i was lucking to get it out...there is just nothing to grab. The old stuff was in fine shape so I put it back in. Saved the tapered set for my 79 which will need swing arm bushings and the steering head looked at.



Changed the fork springs for progressive wound springs.


Got these nice stainless center stand bolts from MikesXS. They have a grease zerk too.

[srust58]

hopefully the last of the polishing...for a little while at least.


So this is where the project stands at the moment...out of the basement and into the assembly area.

[srust58]

Made up a new rectifier. Three phase ($14) with heat sink ($1.20). Will mount in the same place as the original.