|Subject:||RE: One year on....||Date:||Mon Jul 7 05:50:14 2008|
Thanks to everyone for their comments via both the Exchange and direct concerning my update posting. The most popular comment was that my mpg was poor. I know - I said so in the original posting and I also indicated that I would be doing something about it. The second most common response concerned the lighting. Again, I said I felt there were still improvements to be made. I have already converted to a two brush operation amd fitted an electronic regulator (though not one of yours Gene - sorry! Yours came on the scene after I'd done the conversion). It's always good to hear from fellow Hen owners and hopefully we can all share in our experiences and help each other. Even the 'I get 100mpg' and 'my lights are perfect' comments are appreciated although it would be useful if you let us all know how it had been achieved....|
Anyway, the main reason for this posting is to let you all know that the above problems are minor compared to what happened last weekend. Having just said how well everything was going, I took the bike out for a ride and after about 60 miles it suddenly slowed very quickly. Dipping the clutch made no difference, the engine was ticking over nicely but the back wheel was locked solid. Gearbox/rear wheel then. It came home in the van.
I've stripped the engine completely and found a crack in the crankcase in the area of the mainshaft bronze bush - the one between bevel and sprocket. What's more, the bush has revolved and has stripped the thread in the crankcase in the process. Possibly, the shaft seized in the bush and caused to to turn. The shaft shows a slight bronze colour but no damage. The bush still feels smooth and revolves freely enough. I have noticed though that the oil grooves appear to have very sharp edges - I would have de-burred them after manufacture - and I can't think of a reason for that at the moment. If the bush did seize momentarily, it would turn in such a way that it would attempt to screw into the case, thereby taking up all the endfloat on the gears fitted to the mainshaft - I reckon this would lock up the wheel. There are three things that should prevent the bush turning. First, the two bolts either side of the bush should clamp the bush between the two crancase halves. This would have become pretty well ineffective once the case cracked. Second, the 1/4 bolt should screw down into one of the holes in the bush to prevent rotation but it seems that it was not quite long enough (whoops!) The lock ring on the bush is the third method. If the bush rotates, the left hand thread on the ring would tighten up and attempt to pull the bush out of the case. The ring has screwed up to the end of its thread and then taken a lot of load - it is noticeably dished! I'm not sure if the crack was the start of the problem or whether it was caused by the problem.
So there you are! Sometimes I wish I'd keep my big mouth shut! I was tempting fate telling you how well things were going! Yes, I made a mistake in not making sure the 1/4" bolt seated well into the hole in the bush. I don't mind telling everyone my failures (well, some of them anyway!) I'm telling you all this in the hope that others can learn from it.
The cases are now completely stripped and cleaned ready for welding so here we go again.... Watch this space - I'll be back!
----- ORIGINAL MESSAGE FOLLOWS -----
As itís a year since my Model K finally got back on the road after fourteen years of work, I thought some of you might be interested in an update. Some problems showed up very early.
The gear change linkage needed some work. No matter how I adjusted the connecting rod length I could still only get first or third gear but not both. At first I thought Iíd need to re-drill the hole on the gear change lever higher up which was annoying considering how much effort Iíd put into working out where the hole should be in the first place! Then I noticed what the problem was. The brass lugs soldered onto the tank to hold the gate in place both had a square end on the inside. As the lever moved towards the end of its travel, the leverís spring plate hit the lug preventing it from reaching the notch. My original calculations on siting the hole were done before I had fitted the spring plates so I had missed this. Not a problem though - all I had to do was chamfer each lug so that the spring plate could ride up over it. The tank came with my original kit of parts but I found very early on that it was fractionally too long and too high to fit between the frame tubes. Iíd cured that problem long ago but that, plus this problem with the gear change, makes me pretty sure the tank was a repro and had never been used.
The gearing was too high. The parts list I had showed 15, 16 and 17 tooth engine sprockets so I had made one of each. I made some enquiries about what gearing others were using and did some more sums. I decided to reduce the 17 tooth engine sprocket Iíd originally fitted to a 15 tooth one. This, together with the 36 tooth rear sprocket, cured the problem.
The speedo works fine but the odometer part reached 9.9 miles and refused to turn over to ten. I reset the trip and it then reached 0.9 before sticking. Iíve had a look inside and can see where the problem lies but havenít been brave enough to attempt a repair yet!
I didnít find it easy to see the oil level down through the filling hole so I made a dipstick which attached to the underside of the filler cap. It needs to be able to go round a corner so I made it from a piece of control cable outer casing so that it was flexible. On the lower end, I soldered a piece of brass tube with a groove machined half way along. This groove, together with the top and bottom of the brass, were made to line up with the three steps in the crankcase used to determine correct oil level. A good job Ė itís very easy to check the oil now.
The oil pressure gauge for my Model K should have been 0-20psi but I had only managed to find a later DeLuxe 0-50psi one. The full scale needle movement covers only a small arc and I found that my relatively low pressures were not very easy to see when riding along. Then I found a 0-35psi gauge on eBay. More importantly, it covered the 0-35 range over approximately 270 degrees of needle movement. It might be the wrong scale but it was manufactured by the US Gauge Co and has the correct logo on the face! This was something I just HAD to have so I bid outrageosly high and then won it for peanuts. The new gauge is much easier to read while on the move. Pressure is 20psi when motoring, dropping to 15psi at tickover Ė Iím happy with that.
Iíd fitted a brake stop light (the interests of road safety won the day over originality) but the bulb was rated at 21W which at 6v means 3.5 amps Ė probably as much as I could reasonably expect from a DU5 generator. Not a problem during daylight hours but with the lights on, when I put the brake on, the ammeter showed a very unhealthy discharge. The first night time trip involved about 15 miles with the lights on and they were pretty dim by the time I got home. I broke the glass envelope on a stop/tail bulb and soldered some white leds and resistors in place to make a low current rear lamp. This works a treat - the ammeter doesnít even flicker when the brake is applied. All available power is now used by the headlamp and the generator just about keeps up with demand provided the revs are kept up. I feel there are still improvements to be made here so Iím still experimenting.
Now all the above sounds pretty minor and easily sorted but I have to admit, there has been one real big problem. Iíd done lots of trips up the road and back but was starting to venture further afield. Thatís when I found that I could only do three or four miles down the road before the engine tightened up. First time it happened, instinct made me grab a (non-existent) hand clutch lever and by the time Iíd remembered it had a foot clutch, I was leaving a black stripe down the tarmac..... Luckily, once it had cooled down, it restarted OK. Now I knew there was a problem with overheating, I kept rides short and if I wanted to go for more than a few miles, Iíd pull over and wait for it to cool off before carrying on. Despite this, there were three or four occasions when I felt it tighten up but managed to disengage the clutch before it locked up solid. I hoped it was just a case of carefully running in so persevered with lots of short runs. After a hundred miles of this (yes Ė it took a very long time to cover this distance!) it was time for itís first oil change so it was up on the bench. Thatís when I decided Iíd have to take a look inside. The pistons on cylinders two and four showed signs of seizure. I also found that the inlet manifold had cracked on the rear cylinder flange creating an air leak which wouldnít have helped. I made some aluminium Ďgasketsí and welded them to the inlet manifold. Once cleaned up I had thicker flanges but they were of decent aluminium alloy rather than 1920's cast alloy. Of course, then I had to make some slightly longer studs..... I gave a lot of thought to the pistons and finally decided to reduce the diameter to give a little more clearance. I went from 5 thou to 9-10 thou and also cammed the sides. When it was all back together, it turned over considerably more easily. When I started it up, it sounded fine so I set off down the road. It went straight past the spot where that first seizure occurred and then came up to a red light. No air flow over the cylinders now! But no problem Ė at the green light I pulled away and did a total of 12 miles in one go! Now we were getting somewhere! There followed several evening runs with the local clubs which averaged about 40 miles each time. I also entered a couple of local all day runs, one of which was about 60 miles, the other about 85. In the last six weeks since getting the overheating problem sorted Iíve covered about 500 miles. In fact, whenever Iíve been out on a bike, itís been the Henderson Ė Iíve even been using it for general transport! Itís running in nicely, handles well, is comfortable, starts first kick, pulls easily from 15mph in top if I retard the ignition a little, runs happily at 50mph (for short distances of course Ė well, I am still running in!) and even the brakes seem to be getting better as they bed in!
All the above mileage figures are approximate Ė the odometer still hasnít been looked at - but even so I have worked out some petrol (gas) consumption figures. Iím getting about 28miles per (UK) gallon which gives me a range of only about 60 miles Ė small tank on a Model K! A bit annoying when all my riding buddies park outside the petrol station to wait for me while I fill up! There is no reserve on my bike so if I run out, Iím right out. For this reason Iím currently making an auxiliary petrol tank to fit down between the rear frame tubes on the left hand side. I reckon it should hold enough for maybe 20 miles. Once this is finished next job will be to look at the carburettor. Itís currently running a bit rich but Iím not too worried about that while Iím running in. Itís more than just adjustment Ė Iíll probably have to make some new jets.
So there you have it Ė twelve months on and the grin factor is even bigger than ever!