This is an update to my first article written in 1996 (see Fred's Norton Road Racer), shortly after I completed the bike. A number of things have changed on this bike since it was first raced, so I wanted to do another article updating the changes and commenting on the problems with the first bike. I will assume that you have read the first article and will not repeat things in that article, but highlight the changes.

I am on my fourth engine, and this is the first engine that I have build myself. Being new to racing when I first built this bike, I figured I would leave the engine to the pros and concentrate on the rolling chassis. The rolling chassis has proved to be very reliable, so the only improvements were to enhance handling or efficiency. I will talk about the chassis later. For now I want to talk about the engines. The first three engines were built by different people due to lack of experience or time on my part.

The first engine may have been the fastest, but proved to be a hand grenade. The main problem with this engine at first was the wet-sumping problem with a 1972 crankcase (see my article Oil Pressure Loss, Norton 750cc (1972-73)). After I finally figured out how to keep the oil off the rear wheel and started to feel like a potential racer, I blew up the engine. I broke the left side crankcase in half horizontally through the main bearing race, cracked the crank and cracked the cylinder. Besides ruining my day, I was not appreciated by the two racers that went down driving through my oil after my case broke. Fortunately for me it was a left-hand turn and the oil missed my bike until I straightened up to get out of the racing line. I do not know what failed, but think I will stay away from 12 to 1 compression.

The second engine was a lower compression version of the first with used crank and crank cases and a new cylinder. We used the same head and cam. This engine also broke the crank, which broke the crank cases the same way as the first. Since the cylinder was through bolted, it survived.

The third engine, a short stroke 750cc engine, was an experiment. We used a used Triumph crank, with Triumph conrods, Norton 850 pistons and cylinder. We only had this engine on a dyno once, but the power curve was beautiful. The engine was designed to run 11 to 1 compression, but went to the track with only around 8 to 1. We never got the chance to thoroughly tune this engine before the crank went on it. We reinforced the crankcases so they did not break in half, just pushed the main bearing out the drive side. I do believe this would have been a screamer and will persue this idea again with a billet crank and new cases. I ran a magneto on this engine for the experience and liked the simplicity of it.

The fourth engine, which is in the bike now, is using the crank cases that have matching numbers to the frame. How I have not broken these cases yet I will never know. I am using a version of the PW3 cam, the head from my first engine, new cylinders and a good used crank. I am running 10 to 1 compression with twin Amal 34mm MKII carbs. The exhaust pipes are 1 5/8" diameter instead of the normal 1 3/8". I am leery of used cranks for a racing engine, especially with my history. I have a new set of Andover Norton crank cases, but have been oscillating on what version (normal stroke or short stroke) billet crank to put in them and ran out of time, so I went with used crank and cases. I did not want to use the new cases with a used crank.

I have had a problem in the past seeing my tachometer well into the 7000s and occasionally higher. I blame most, if not all, of my engine problems on this problem and am swearing to use 6500 as my red line. I know you can turn a Norton to 7000 all day long with a new crank, but who knows what the history of used cranks are. I have magnafluxed all the used cranks that I have used.

The original gearbox lost third gear and luckily did not lock up. I took the box out of my MK3 which I bought new and ran that box for one season due to laziness. This bike has a completely new gearbox. I installed an outrigger bearing last year and found that it really helps shifting by eliminating most, if not all, main shaft flex. I only run with a kick start when I run on the street. We start our bikes with rollers and this bike bump starts easily.

I had to change the exhaust system for two reasons. I wanted to increase the standard exhaust diameter to 1 5/8" which allows better flow for ported heads. The first exhaust system tucked next to the frame as close as they could, but I nearly wore the pipes completely through. The new TT pipes are made for Old Britts by Viking and bolt directly to the engine mount where you would mount the center stand. You do not need to isolasticly mount the pipes if they are not bolted to the frame. I am running Supertrap mufflers, which pass our noise restrictions.

After I went to the TT pipes and eliminated the pipes scraping, my foot pegs started to scrape. I took the stock Z brackets, cut off the passenger/muffler mounting part and moved the foot pegs up and in. The foot pegs use the stock front top foot peg bolt hole. I had a problem with the foot pegs rotating and folding down while racing, even though I safety wired them. To fix this, I made a bracket that has a square hole and squared off the mounting end of the foot peg.

I am running 520 chain instead of 530 chain. The 520 chain is lighter and allows me to have interchangeable rear sprockets. Since I am running a MK3 rear wheel, I had an alloy sprocket carrier made to accept OSSA two-piece sprockets. The two-piece sprocket allows changing sprockets without removing the rear wheel. I have not used this feature in the pits, but it is a neat feature.

Oil catch bottles are required to race and you should have one on your street bike. Draining the oil tank on a Commando is a pain, and to check the oil level requires removing the seat. Because of this, I designed an alloy oil tank that has a built-in catch chamber, which allows filling and checking the oil level without removing the seat; and best of all, there are two hoses that run to the bottom of the bike for draining. There is an alloy junction block at the end of the drain hoses which also serves as one of the mounting lugs for the left exhaust pipe. This tank does not require side covers to finish off the appearance--at least that’s my opinion. There is a removable battery box, so when I am running constant loss ignition, I can mount a battery. If I am running a magneto, I can remove the battery box. This bike is licensed for street use, which I only do for testing. When I did this and was running a mag, I hooked up my lights on a constant loss system.

I did remove the alternator and run a constant loss Boyer ignition. Constant loss is a pain making sure the battery is charging; but it removes a bit of weight, increases horse power and makes wiring a lot simpler.

I did add velocity stacks to my carburetors, which I'm not sure is a great idea if you weigh the performance enhancements against the possibility of ruining an engine if you go down and the bike slides through dirt while running--but they are pretty.

I mounted a production racer fairing, which really helps at speed--especially for someone like me with a bad neck who can't get down on the tank. I guess I will never be a world champion. This type fairing normally mounts the lower sides to the front down tubes of the frame. I did not like the mounting brackets that came with the fairing, so I manufactured a bracket that bolts to the Norvil head steady and comes straight out from under the gas tank. The fairing is secured with five dzus fasteners and can be removed in seconds. I also manufactured an alloy dash panel that holds the tack, oil pressure gauge and a space for a speedometer.

For more rear tire, I changed out the WM3 19" rear rim to a WM4 18". This allows me to run an AVON 120/80 V18 tire.

Almost all fasteners are stainless steel and safety wired. It is not required to safety wire as much as I do, but it makes bike preparation prior to a race much easier. All you need to do is tweak the wire and you know the fastener is tight. Safety wire also allows you to use less torque to hold the fastener.

The next two pictures are of me and my bike and me on the bike garage racing. The black pouch on the back of the seat is a transponder which is required at the tracks that we race. The transponder provides finishing positions and lap times.

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