torsdag 21 juli 2011

The pocket valve (Google translation)

There was a Harley 1926 model J 61” with sidecar for sale among classified ads in the Daily News. They asked 35,000 kronor or 5100 USD and the bike was in a barn north side of Stockholm. I went there and met a nice gentleman who showed the bike that was in parts and he told me the bikes history.

His father had bought it sometime in 50ies and rebuilt the bike for hill climb race.
He lowered the sidecar frame 8 inch and mounted cross tires, but otherwise the bike was standard. He took the fenders and side car cage off in for a race.

He competed successfully with the bike in the area around Stockholm. The bike was painted later on sometime in 60ies in a green / yellow hue and a very primitive red hand striping. It is ugly.

His son took over the bike 1968 but did never get it back together again so it was lying in almost 30 years before he put out the ad.

I went home after the screening but found the bike very ugly and also a bit pricey and forgot about it, but a few months later I saw it in a dream and could not let go of the dream, I had thrown away his phone numbers so now it was a challenge to get hold of the bike again. I drove in to DN and sat for hours and read old ads to finally find it. I called the seller and ask if it was for sale? The answer was yes so I went there again and bargain it down to 30 000 kronor or 5000 USD and I struck.

I got it home and started to check that all parts were present and found none were directly damaged or too worn for use, so I picked it up piece by piece until it finally was ready for take-off without any more jobs than new piston rings and grinding of valves.

This was my third Harley half top with sidecar, I had previously owned a 1925 1000cc and 1200cc 1929. Before them, also a 1936 VL with sidecar. Unfortunately, where I had to sell them because I needed the money. But this bike has stayed in my possession since 1992. The reason I initially run old vintage bikes were of economic nature, pocket valve bikes were cheap and so even the side valve bikes at the time.
My first 1200 flat head chopper cost me only about 10 000 kronor or 1500 USD to put together and then I had extra engine and gearbox mm. This was early 70's. I drove the VL for 7-8 years before I sold it cheap, with the promise to buy it back with a lower interest rate. The person later sold the bike and I was blown on the repurchase.

Then came 1925an up, a bike that was circulated among several shops but no one had sorted out the bike so the owner got tired and told me that he do not care about the bike, it's only a problem and I can let it remains on the studio until the rust away. When I said that then well I take care of it instead as we can ride it. Sure, he said, and so we did. But after a few months when I assembled the bike and he got a test ride so he took it back and sold it and I did not get a dime for the job. Stupid as you are so confident you on people, I was going of course have made sure to get registration papers at the same time with the bike. Anyway, it was this bike that hooked me on pocket valve Harleys.

I'll never forget the first time I got it runnig, I had run with the over one kilometer, it refused to strat, it just poof and slammed. I sat by the roadside and gasped, it was the yarely morning sunrise (wonder why all the premieres starts usually occurs in the middle of the night?). When a car stops, it is a friend from a biker club with his company car, full of tools, on his way to work. We discuss a moment and check it one thing or another. We pull the intake bolts properly and set the valve timing. Then I try to kick. The bike started on the first kick and runs like a clock. I ride it home to the garage and fell asleep exhausted on the sofa.

After that day, I have driven half top Harleys all year round, with a short interruption when I could not afford to renovate the machine. As my finances were not the best so I maintained was not done properly without it, I took any part what i could find to run a few more days, it has been pistons from all car and motorcycle of possible and impossible brands. This, in turn, helped of course that when the engine was warned out, it was completely worn out. Everything needed to be fixed, for example, I've probably worn out and cracked 10's pair of cylinders through the years.

I especially remember the first time I welded a half top cylinder ruptured. When I discovered the crack rang a welding company which was near my home. I asked the finnish guy to be ready to go by the MIG welding machine when I get about 10 minutes for us to weld a hot cast iron cylinder. So I started up the bike and drove it really hot, then down to the blacksmith. Then he stood there with electro-welded and cast iron stick and asked where the cylinder was so he could weld. When I tap on the bike and the cylinder that was cracked. He wore stare at me like I was crazy (which I am) and said it's not possible. Well then I said, it is hot now and after we have been welded on so we start immediately and so I drive an hour and keep it warm so that all tension is released. Yes I said the Finn, and persisted in welding with electro-welded in place for MIG. He tried four different sticks, but none was successful. Then I said, get the MIG here now and I'll show you how.

I had some years previously tested all welding processes on one flathead cylinder, I cracked and it worked best was MIG. It had cracked off in cylinder foot because I “forgot” tightening the cylinder base nuts. I thought then, this means I have to unscrew the engine, remove the cylinder, heat it up in the oven, welding with Castolin or braze, after cooling in three days and then see if it went well. I wanted ride so I hit a block of wood under the tank and frame to drive down the cylinder base, brushed clean with a wire brush and treated the crack with the weld. Micke Edlund stood by and laughing, (he has built maybe 1000 rigid Harley frames) and asked to try out a seam. 5 minutes later I was riding again. This welding was also functional for years.
Weld´n run
No welding work optimally in the old rusty cast iron cylinders because they both have an extremely high carbon content but they also have roasted the way through so it is quite impossible to find pure goods to weld in how hard you grind.

My technique is to point weld with MIG, first just so you hit the crack and burns off the carbon, then next round and get some of the weld to attach to the rusty iron, then welds it together is the third round by targeting only the thread of the previous welds and allowing the melt to flow together by itself. This is repeated a few times until it receives a dense and wide weld. It will drip and drain a lot of dross, and that's probably the only way to succeed. Through the spot welds that cannot keep all slag run off without interfering with the welding rod material, then gradually after a few turns, so does the content of weld material in the melt and eventually welded passably. It is not pretty but it works. I had to go back to the blacksmith two times to add more welding but then kept it going with for over 4 years. Of course it is possible that both the braze and weld these cylinders but they may not be as rusted as I have gotten hold of, but in good condition. But even then there can be problems, well.

I ran the engine red-hot again and attacked with MIG, I had to knock out the flanges so that until there was not any left. Because when I welded a top crack as it broke the shrinkage in flange row below, so it's just to weld on, lap after lap until the crack is ended. I split the welded cylinder in the middle to see what it looked like inside. It was completely full of cracks, it looked like a spider web. But I had not welded through in one place. This is also an important thing to consider if you need to weld a cylinder. Be careful not to weld through, add rather a lot of welding on the outside until you get quite close.

Since then it has been drilled on, welded and replaced pistons a lot. Meanwhile, we wondered why the crack and struggles. Partly because it's that you drive with large tolerances and tired parts, given way causing high temperatures which in turn creates serious wear. A well put together half top engine with the proper tollerance is very well suited for everyday use in normal circumstances. But even such an engine is very hot and are hard on the pistons, rings and cylinder bores. Although valve guides and seats may strike.

There are two screw valves on the top of the cylinders, it says in the user´s manual that is for schnapps gas for cold winter start. But I think this is a mistranslation, because I've never had problems starting in winter, it is rather the opposite, so I suspect that these rather is designed to inject oil into the cylinders when they run very hot. Since the lubrication system is not directly push the oil in the cylinders so the lubrication system is difficult to recreate the oil film in the cylinders if it burned up.

If the engine was hot pinch because of high stress and heat build up and stop. So tear pistons and rings coarse scratches in the cylinders before the oil withdrawn to the dry surface when you start it up again. If things go badly then the oil is never there because the cylinders very quickly becomes hot again because there is no film of oil, they run totally dry. It becomes a vicious circle lubrication system cannot cancel. At least I have been using these screw valves to provide an oil shower when it went heavy to run or stuck. I now have even gas cap cover with snaps syringe into the tank so I can easily restore the oil film if necessary.

This applies to race engines or engines that run extremely hard. Pocket valve engine running on road in peace and that is well renovated will probably never be hot pinch without slapping on the many thousands of mil without any problems. But as I said, I run like hell with my bikes and then I have this problem. I bought a thermometer from Hansen Racing, the related probes have tapered thread that fits into the holes for syringe nozzles. On my new engine I have mounted probes in both cylinders cause I do not need the helping oil due to a perfect engine restoration and my secret trick.

Something that has fascinated me since the very first pocket valve engine is that it has both torque rpm. This I learned from the 25 bike, I had driven it a few weeks in the same way as I drove my flat head. Early gear shift and ride on the torque. But after a few weeks with this style of driving the engine started losing power, I turned on full throttle and let it rev like hell. After that it went on as usual, I had sat back and sweetened it with my low speed driving. I am amazed every day that it not spikes when tagged in 4th gear at 40 km per hour and rotate fully, it just takes off without protest. It's really impressive heavy torque at low revs and how it can wind up and also have the power there.

More to come . . .