Finally I’m back after what seems a long time. Sometimes life gets in the way of bike building. I still haven’t finished the Honda 750 four project yet, but I felt it was time to to start another project bike. I am re-thinking some of the components on the Honda, so a little more time before completion won’t hurt. I am a man with a lot of patience, which is what you need when you build a quality motorcycle.
On to the bobber project. I never built a bike from spares, so this is a new one for me. A couple of years ago I bought a T140 frame and engine cases with the intension of doing something with it later. I had the idea of turning it into a bobber. I like the idea of a really simple rigid framed bike with no flash chrome, fiddly bits or flashy race parts. I know I wanted a big fat tank and seat and not skinny wheels. I wanted it to look old school, but with a more modern twist.
While I was thinking about the design of the bike I thought I’d start by building the engine, as I knew how I wanted this to look. When you have only the cases this is easier said than done. All the other bikes I’ve done have started from a complete bike, so I now had to source the entire contents of the engine. Luckily over the two years of collecting parts I had picked up most of the big parts like the barrel, crank, head and gearbox. Now commenced months of looking through parts lists and working out what I already had in boxes and what I needed to buy. I did end up buying more than one of quite a few parts, because I couldn’t remember what I had. The tip here is to be anal about it and make careful lists of parts you have and the ones you need. Because I was getting confused with parts I decided to build the engine in stages. I decided to put together the bottom end, then the barrels, then the gearbox and then the cylinder head.
1. T140 engine being built
Firstly I dressed the cases with a file and grinder. I like to clean any casting lines and excess mouldings of the casings. I then aqua-blasted the cases, fitted new mains bearings and then painted the cases with PJ1 statin black engine paint. The crank shaft was balanced and the new standard camshafts were fitted. I mated the two cases together with wellseal. Terry rebored the barrels to fit the pistons I had, and I painted them with PJ1 gloss this time. Once the barrel and pistons were on I assembled the gearbox. Writing it here makes it sound very easy and striaght forward, but my main problems were hold ups due to not having all the small parts like specific bolts and washers. This is the main problem when you are building from spares, also you have no point of reference, because you never took the bike apart to start with. That’s why here at the workshop we prefer getting whole engines in for rebuilding, not in 1000 pieces to start with. Its not to bad with the engines we are familar with and the older British engines, but some of the late Japanese fours can sometimes be a bit taxing. It takes time to read through manuals to make sure you have all the parts. Also when you take an engine to pieces it can give you clues to how its been running and indications of possible problems its been having.
2. Cylinder head prepared for fitting
The engine was now built without the primary. My thoughts turned to the frame. The problem I had was, do I modify the T140 frame or get an earlier frame. The T140 frame is very heavy, because of the oil in frame and unfortunately the one I had was badly rust scared, so this really decided it for me; a new frame was needed. Luckily I found just the supplier in Dick at ‘The Barons Speed Shop’, a top gezzer. The frame was only £350 with the rear rigid back end kit coming in at £99, all made by ‘Factory Metal Works’. Terry made the wheel spindle then made and welded the mounts for it. The spoked wheels I had bought were from a KTM 690 super moto, were twin 17″, so they will require some engineering to get them to fit. This I will discuss in my next installment.
3. The rigid back end is made for the 17″ KTM SM wheel
See you next time.
Colin
