As you recall, I decided restore the 175 Dual Twin and gave myself a limited budget and time frame to do it in. Judging by what I have seen so far, this should be the easiest project I have taken on. I am not a mechanic by any stretch, (I do plan on taking a small engine repair class in the fall) I have friends who played with Lambrettas and Vespas for years and know two strokes intimately. The fact that the engine turns freely and has decent compression has me feeling good about the outcome.
Here is where we are at so far in no specific order;
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| Peek a Boo! |
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| Massive Air Filter! |
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| Surprisingly, not to bad after a little elbow grease! |
While I was initially worried about my lack of metric tools, it turned out that all I needed was two 14mm sockets, two 10mm sockets and a small wrench with 10mm on one end and 8mm on the other. That last wrench was a snap-on that I found lying on the road when I was out on my Triumph Scrambler one day... staying observant has its rewards!
It all came apart with remarkable ease, no use of propane torch or hammer required. In the course of the strip down I noticed several interesting things. From a technology perspective I will start with the frame. It is a tubular design, most contemporary Japanese bikes had a pressed steel frame (as the Sport 90 does). Not only does this look more attractive, I am certain it handles better as well.
Bridgestone were known for racing and even took their class at Daytona in 1966. The footage of that race can be seen here.
Further to this, the engine is equipped with dual enclosed carbs and a sophisticated yet simply constructed air intake system. This allowed the rider to go off road without anything getting into the carbs. Air was sucked into the giant air filter (this thing is like a little cannon!) then into a chrome tube straight to the enclosure. I imagine it much easier to adjust from the side then from the back of the engine.
The engine also featured 'sport shifting' which would allow the rider to have either a 4 speed transmission or switch to 5 speed. I am still trying to wrap my head around the rotary valve system and some of the other details of this interesting little machine.
Now onto finish. I have never been a fan of Japanese chrome, especially the vintage variety. It tends to be paper thin and can sometimes be peeled off by hand in extreme cases. I was quite worried about the rust on the rims, shocks, bars...etc. I was imagining having to scrap a whole pile of parts, something I loathe doing. I will do anything to avoid scrapping parts, which has led me to do a great deal of experimenting with tools, rust removers and other solutions.
My old standby is WD40 and 0 fine steel wool. I have saved many a British rim with this method and then a treatment with Autosol. I am very pleased to report that these rims appear to not only be salvageable, but should actually look quite good when finished! I was a little surprised that rear tire looked fairly new, no cracking or dryness and the treads are in great shape. It's fairly clear that this machine could not have been used in a number of years, based on the condition of the battery (the original battery from what I can tell) and the colour of the oil. Another mystery I will never be able to solve is the crack in the top yoke (or top tree if you prefer). How the hell does one do that? Probably the same incident that cost the bike its headlight and front mudguard.
I will be leaving a great deal of parts in white vinegar to see how clean I can get them and then sandblasting the larger items. I am also trying out a UK made rust removal product that my father picked up at Lee Valley.
It is mixed with 5 liters of waters, parts are submerged then washed off. I am currently soaking the rear shocks (which seem to have a lot of life left in them) they are badly pitted, I am hoping I can rescue them.
Certain items are going to be binned for sure, they are just too far gone. Shifter and brake pedals, probably the handlebars (which appear to be from a different model anyway) and the rear brake arm.
The rear mudguard is nice and straight but badly oxidized. I will sandblast that too.
Now I just need to pick out some colours.....
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