Settling in with 3 1/2 Sport

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I purchased a 1974 or 1975 3 1/2 Sport (No. 05774) about 3 months ago that appeared to be in pristine, almost new condition. However, as with any old bike, there were "issues", nothing major, just "stuff" that needed to be taken care of if it was to be a frequent rider rather than an art piece or Sunday bike.

Problems: Brake cables had way too much friction; clutch was way too heavy; there was blowby from the header/exhaust port junction; the bike did not idle; the bike lacked power; it needed a rear brake cable; two of three idiot lights were burned out; the electrical petcock had been replaced with a manual one that leaked; the taillight was out; it did not have turning indicators; it had a timing belt of unknown age and mileage, and lastly, it did not have rear sets.

From riding the bike I knew it had potential, especially given its gossamer weight. I ordered nylon lined brake and clutch cables and discovered the PO had installed an upper brake cable that was way too long. The new cables immediately fixed any braking issues, they are smooth, make the brake much more progressive, and the action is much lighter. The clutch cable came with too long an outer casing, making installation impossible. A little work with a dremel tool and pliers fixed this, however since this is a common issue with these cables, you think Venhill would have sorted this out by now. Clutch MUCH lighter and progressive.

Turns out the exhausts were lacking the two "C" rings that keep the locknut from overriding the flange of the header. Someone had mickey moused in some wire rather than obtaining the correct parts. Correct parts obtained, and problem solved (and exhaust sound greatly improved as a bonus).

Working on the idle problem, stripped down the carbs and cleaned them, but discovered that they were lacking "o" rings and washers in the fuel mixture and idle screws, and the gaskets on the tops were missing. Also, two clamps on the airbox hoses were missing. Once proper vacume was attained, bike now idled. While checking the air filters, discovered airbox was filled with acorns, grass and other various items of rodent detritous....looked like someone set up house in the airbox....I now consider them evicted, and I hope they do too....took the bike for a spin, and power problem solved... can't believe this bike is only a 350, it runs more like a 750....

I could have replaced the idiot lights with new incandescent bulbs, but opted for LEDs. Got some super white single LED bulbs and soldered them onto the contacts. These are vibration proof and much brighter than the stock bulbs. Should last the life of the bike. Needed to add a 480 ohm resistor in line to prevent frying them, as they consume only 2 volts or so. Likely could have found a replacement LED bulb on Ebay, however this still would have required soldering in a resistor still....

Got a rear brake cable with inline swtich and installed it. Also got a micro switch for the front brake; having to make a bracket to get it to work. Wiring was the most hassle, but now have brake lights for front and rear brakes.

Taillight was a dirty connnector, and while I was at it I went through all connnectors on the bike and cleaned and greased them.

Petcocks were a problem. Could get a replacement that does not look like the "sugarcube" Brev Orlandi type units that came stock, but opted for Brev Orlandi look alikes off of Ebay. Turns out, quality was not too good and I did not trust their longevity. I purchased a square of gas resistant rubber sheet along with a punch set, and made new rubber gaskets which I then glued in to replace the old gaskets. Fix appears to have salvaged the old petcocks, at least for now...

Installed turning indicators with a CEV switch and electronic flasher (rather than thermal/wire) relay, so I could use LEDs for the bulbs. Works great.

Ordered an "A" belt and flywheel puller from NLM and also ordered Goodyear replacement belts, will try to determine which one to install, but this is the next project.

Rear sets are Tarozzis, however the stock lever of course fouled both the footpeg and toe peg. Got a "Swan neck" lever from NLM that fixed the footpeg fouling, but not the toe peg. Got a new shift lever "knuckle" or "boss" from NLM, and this, combined with shaving a few mms from the toe peg, fixed this. The NLM boss has more offset over the stock item.

Bike is now an everyday rider, if need be. Starts first or second kick, idles, and makes surprising power. Combined with its light weight, makes it a great handling sport bike. It will not keep up with a modern bike on anything but a very curvy road, but it is a perfect bike for riding in the mountain canyon roads that abound in Southern California.

[mantaray]

Ordered an "A" belt and flywheel puller from NLM and also ordered Goodyear replacement belts, will try to determine which one to install, but this is the next project.

Changing the belt is a priority unless you know the history of the bike.
Have fun with the 3 1/2

Raymond