Having done a number of Super Hawk repairs/restorations in the past two years, it becomes apparent that some of the parts necessary for a complete, running motorcycle have become very difficult to obtain recently.
Honda sold over 80,000 CB72, CB77s, just in the US, with other variations such as the CP77, CYP77, CBM72 and even the 1961 CM72 all using the same basic parts. Only the 1961 models had a slightly smaller petcock assembly, using a smaller lever and body. The parts were standardized in 1962 and continued on until the end of production in 1967. Honda chose to delete the crossover tubes in the 1967 editions, which called for a petcock without the extra cross-over fitting, as well. But for the vast majority of the Hawks and Super Hawks, the petcocks are the same.
Recently, it was necessary to “repair” one, as much as possible for that last 1963 CB77 BlackHawk Special, as there were no spares left in inventory and nothing was available on eBay auctions. A NOS petcock offered at $100 was shown briefly, but someone snatched it up quickly, just last month.
A recent purchase of a used unit, plus another which came to me with a box of spare parts, both displayed some deterioration and splitting of the brass fuel tubes. While you can order all the soft parts for the petcocks, like the 4-hole gasket, fuel bowl o-ring, fuel cup, petcock nut seal and brass screen, the body comes with the fuel tube installed, pressed into place and is not available as a separate part. As with the petcock bodies on the Dreams and Scramblers, the main petcock body for the Super Hawks has been discontinued and is hard to find in decent condition.
It was necessary to hand file the threaded portion of the BlackHawk petcock, because part of the threads were ripped loose. About 20 minutes of hand-filing squared up the end just enough to get a seal to seat on the edge, but it leaked in the first installment. The threaded portion was reworked once again and a brake fitting washer was ground down on the outside in order to become somewhat of a crush washer that also added material height to the threaded section of the body. That, coupled with a generous application of Teflon tape, created a fuel-proof seal, but it isn’t the best solution for the long-term.
Looking at the two latest acquisitions, the fuel tubes were obviously not going to do their jobs in separating the top half of the fuel load from the bottom half, where the reserve ports take over. It seemed that the tubes were just pressed in, so a method was developed to replace the tubes with new material.
First the old tubes needed to be removed and that was a challenge due to the lengthwise cracks of the original brass material. A matching sized drill bit was slid down inside the tubing, as far down as possible and the reinforced tube was clamped with Vise-Grips positioned near the petcock attachment nut, which was left in place to protect the threads. Using some wide bladed screwdrivers as wedges against the Vise-Grip jaws, the old tubing was jacked out of the hole in the body, coming out in one clean piece.
This confirmed that the tubing was just a pressed fit and not otherwise secured with adhesives and was not cast in place. The tubing measured 5mm on the OD, so a quick check of eBay listings turned up some 5mm OD tubing at a hobby/craft seller’s site. So, for the sum of $7.90 a set of three were shipped to me with free postage, as well. Each tube length is about enough to make three fuel tubes, so it’s a cheap and easy way to find the right material for the repair job.
Once the tubing was cut, the ends had to be squared up and slightly tapered to get a start into the petcock body hole. I measured the end of the original piece and it was down to about 4.85mm. One supposes that it compressed/crushed down from the original 5mm diameter during installation. The rest of the used tubing was about 5mm, so it was just the end that was made into a pressed-fit tip. At any rate, with some judicious use of a brass hammer and holding all the parts in alignment, the brass tubes were tapped into place and feel securely located in the process.
So, the end result is that two petcock bodies which most people would probably throw into the scrap pile are now kitted out and ready for use. The next time the BlackHawk CB77 comes back in for service, the petcock will be replaced with one of these two, so that full petcock function can be assured for the future.
Bill “MrHonda” Silver