Be sure to visit the SOHC/4 Web Site for more information on Honda and the SOHC/4 Motorcycles.
0 Members and 1 Guest are viewing this topic.
It's a 1975 CB750K5 frame with a CB750K1 engine, but I'm discovering more and more that it's a bit of a Frankenstein in terms of parts. Here's a couple pics, let me know if you need other angles, and thanks.
Quote from: SCRob on September 07, 2012, 02:05:20 PMIt's a 1975 CB750K5 frame with a CB750K1 engine, but I'm discovering more and more that it's a bit of a Frankenstein in terms of parts. Here's a couple pics, let me know if you need other angles, and thanks.You have the same forks as in the video... Well the process of taking them apart. Really simple for a newbie if you are one... I was able to swap out fork tubes from one bike and rebuild another set in less then 2 hours..
AIR FORK: If your Honda is going to weigh less than 500 pounds, install a set of S&W's No. SP1530-19 springs. For a normal weight 750, use the same company's No. SP283BH spring set. The spring preload is critical for proper operation of any fork and especially so with air-assisted forks. After you have chosen the fork-cap assembly you are going to use, you must shorten the fork springs so that they will be compressed one-half inch when the fork cap is screwed completely into the fork tube. The easiest way to do this is to place the spring in the fork tube (with the front wheel off the ground), set the air cap on top of the spring and measure how far the cap will have to travel to seat fully on the fork tube. If it will have to compress the spring 1.5 inches, you will need to cut one inch from the length of the spring; if it must go two inches; remove 1.5 inches from the spring, etc. Trim the spring's length by filing a notch where you want to cut it and bend it back and forth a couple of times until it fractures. You can get the nice flat end by cutting the spring with an extra three-quarters turn and then grinding it on a bench-grinder until the end is flat and the overall length of the spring is correct.Buy a set of 1976 YZ250 (No. 509-23145-L0-00) fork seals from your Yamaha dealer and install them in the fork legs. These seals are designed for 36mm fork tubes (the Honda's are 35mm), but they work very well in the Honda, having less friction than anything else available. Also, since they were designed for air fork use, their grip on the fork tube is not increased much with increased air pressure, as with standard seals. Put them in carefully by tapping around their edges with a soft punch, or use a large socket. If these seals are distorted, they will leak, but they will last the life of the bike if straight.Air forks work best when there is a higher than normal compression ratio in the fork assembly; the oil volume of the Honda's forks should be increased so that there will be a useful rise in air pressure as the forks compress during braking or when negotiating a large bump. Raising the forks' compression ratio is accomplished by adding more oil which lowers the total volume of air. With the fork caps off and the springs removed, compress the forks completely. Pour about 200cc of KalGard 5W fork oil in each leg and pump the forks until all the air is out of the lower portion of the fork assembly. This should take only a few strokes of the forks. You can hear the air bubbling through the damper orifices; when all the air is purged, the forks will move smoothly. Bottom the forks again and fill each leg until the oil is six inches below the top of the fork leg. Install the springs and fork caps.