This started with the idea of reconditioning the head which had worn guides last time it was apart almost 2 years ago, and fitting new rings and shells. It naturally got more complicated. So main bearings have been replaced. Crank split and sludge cleaned out, and re-ground for Mini Cooper shells which are -.050" and a little complicated to do.
One piston was cracked, as was its liner, mainly because I didn't look at it hard enough when fitting, and failed to see the skirt started lower resulting in the piston not being well supported at BDC with part of the skirt out of the bore. I drew up what piston dimension would be needed to keep all the skirt in the bore and Ed V's forged B44 pistons are an exact match.
T/side crank case had a crack to weld and re-inforce, must be the weakest point between the main bearing and cyl, just infront of the idler gear, I've filled the breather hole, which shouldn't matter as its set to breath through the primary rather than the cam.
This is a trial assembly with the old cyls, crank spinns freely and is located by the 3rd bearing outside the alternator. Its even getting new paint, first time I've used 2 pack clear (the softer acrylic wears through so I'm hopeing this will last longer), I'm impressed with how shiny it is straight off the gun.
My expectations were not particularly high, this first set I had trouble getting someone to machine, (Though they did the top and bottom surfaces)so in my hermetically sealed chamber with a cheap drill press, hacksaw, diegrinder, tap seat cutter and file I did the rest, except for boreing and fitting sleeves. I think the basic thing is fine, though I sabotaged myself by thinning the lower sections of the cyls too much because I wanted to fit them without machining out the top of the C/cases and get filings in the assembled motor. I'm hopeing to have a properly machined set soon with Nicasil bores rather than liners.
Re: Overhaul on the A65#212697 12/27/074:19 pm12/27/074:19 pm
This is the new oil can, and pistons in the old cyls, the cases are not a matched set and I've been adjusting the deck where the cyl sits to try getting it exactly square to the crank, which wasn't the case before. I've tried measuring a few different ways with the calipers but it still looks 10 thou or so out looking at the piston at TDC. If I measure off the piston pins the rods can rock very slightly, measuring between the hole for T/S mainbearing or D/S oilseal hole and the case deck, then adding half the dia of the respective hole, is what seems easiest. So I've filed the cases deck to match the measurements, and used bearing blue to get it flat in good contact with the block.
Yes, non slip drying rack I only had the one set up, (probably need to send to France for another)so tank and seat were taking turns, the seat was perfect like glass except for under where the tail light goes, hardly visible when together but I had a little clear still in the gun from the tank (on the spray rack), so I sat the seat on a bucket and sprayed the under bit which made it slip off the bucket and roll along the ground. Reminds me of a Harley I worked on, getting the motor running plus painted a nice flame job all airbrushed etc, back brake didn't work but I still tried it slowly up the gravel drive, there was no way to match in all the airbrusing so I got some little stickers made that covered the offending gravel marks, it probably ended up looking better.
Re: Overhaul on the A65#212700 01/01/085:36 am01/01/085:36 am
The std twin carb A65 head weighs 9LB 9.5oz, it can be lightened to 8LB 7.7oz; a worth while weight saving, useing a tool like this:
When I first went to buy a tool for this I could so strongly imagine a brake cyl hone neatly grinding out the alloy I bought it even though the salesman said it would be absolutely useless for my purpose. My son Ben suggested I use a texta to mark the valve seats so as to be able to clearly see the angles I was cutting, trying to accomplish 3 angle seats, to optimize gas flow.
The exhaust seat is black where the 30deg top cut and 60deg cut is in the throat with the 45deg showing a silver ring, the 60 deg is not real wide and blends into a steeper angled port, same with the bigger dia inlet which also shows a 70deg silver throat inside the black 60deg ring and silver 45 ring and black 30deg blend to combustion chamber. For a long time I've been useing oversize valves in 650-750-810 and 883cc A65s. 44.5mm inlets and 39.5mm exhausts, (modified 6cyl Jaguar valves.) Std inlets weigh 70.8g these are 77.9g. I've tried 36mm carbs but boreing them to 38mm made an immediate improvement, and reading the formula in the tech papers in the MAP catalogue on the relationship between valve size and carb size 38mm is closer to the ideal.
The dark areas in the port are epoxy JB weld, filling holes. This is a simplistic calculation ignoring some variables but if power is proportional to the burning of air and fuel then with the same head/carbs and breathing at 100 percent efficiency; 883cc at 7,000RPM = 6181000cc of burnable air per 2 min, 744 at 9000RPM = 6696000cc or 8,500 = 6324000cc. 650 at 9000 = 5850000cc. The relationship is like 61.8HP for the rpm limited long stroke 883. 63-67Hp for the shortstroke 744 depending on RPM peak or 58.5HP for the 650 at high rpm. Feel free to tell me where these calculations go wrong, but note the HP is just to show relationship not actual. At the moment I'm riding a modified SV650 8valve twin with 39mm carbs with 62HP on the data logger at around 9,000RPM it had 55-57 standard. The best from the 883 before was 72HP on the data logger. So in my theory if everything can be made to stay together and the A65 breathing be made to match the 8valve it should make similar power at similar displacement and RPM? So thats what I'm trying to do with the head.
Re: Overhaul on the A65#212701 02/02/082:00 pm02/02/082:00 pm
Working on a new and improved fairing during the last couple of weekends, the previous version had the lights mounted in the fairing which wasn't very convenient, my plan is to be able to remove the fairing with 3 or 4 screws leaving the lights oilcooler and ramair snorkels mounted in place, so I can use it without the fairing, and also access wireing etc easily. The lights are 104mm approx, and I'll run the left for low beam with a 40 or 50w globe wired to the light switch so it stays on with high or low beam selected, with a 100W globe in the R/hand light for main high beam.
Fibre glassing in such hot weather is good because its pretty fast but cutting holes for the lights and oilcooler and trimming up edges, makes one a bit itchy, not being able to stay covered up well enough due to the heat.
This is it from the front, just out of the dodgey mould with holes for lights and oilcooler roughed out. The cardboard box sets the height to keep the fairing off the front guard with the forks compressed. The holes on either side are air intakes for the motor, air goes through 2 snorkels up under the front of the tank to an airbox feeding the carbs. I'll probably also modify the airbox so the whole of the carbs are in it, so I don't have to feed vent pipes (difficult to get at)into the airbox. When it pressurizes a bit if only the carb intake is in the box it can stop the flow of fuel, because the vents to the bowl, unless they are also in the box, will have lower air pressure to push the fuel up through the jets. Like that a light throttle in a high gear into a headwind can get the motor surging to the point of almost cutting out.
Re: Overhaul on the A65#212702 02/02/083:25 pm02/02/083:25 pm
Its had ram air for some years now and provided the carb vents are also in the pressure zone as stated above it seems good. I don't know if it might effect CV carbs worse, because Jap bikes with it can have quite complex systems. Airboxs can be sensative, I enlarged the intake hole on one on a VFR I had and it messed it up, I had a ram air system on that and had to not seal it properly because I couldn't get the vents into the pressurized area, so at least it still got cooler air.
Re: Overhaul on the A65#212704 02/03/0811:27 am02/03/0811:27 am
Mark, Always nice to hear about your projects. We have most of the same hi tech equipment that you have....cardboard boxes, driveways, paint cans, but we lack your ingenuity and brains. You re-invent BSA's, we just try to make what he got run. Can't wait to hear about your project screaming down the interstate at 125mph.
Re: Overhaul on the A65#212707 02/03/086:44 pm02/03/086:44 pm
A bit more progress on the fairing on saturday. If anyone is interested, the front of this fairing gets a bit complex with all the holes for different things, I'd originally made the mould with the outer air intakes and with an opening for a single rectangularish headlight and no oil cooler for Ben's RGV A65. So to fair it in to the twin lights and oil cooler I cut up some cheap thin plastic throwaway pots that my wife had purchased plants for the backyard jungle. Curved the cut strips into the holes and pushed them up against the lights then pushed in second curved rings to give clearence and taped it in place. Removed the fairing, gel coated outside what plastic protruded on the H/light side then added a couple of layers of chop strand and glass. Did similar with the oil cooler hole, and body filled to smooth.
I now need to fit the screen properly and straighten everything up so it looks as square and even as possible, a large difficulty making stuff is getting both sides the same, and its really important on the fairing when viewed from the front.
Re: Overhaul on the A65#212709 02/26/0810:08 am02/26/0810:08 am
This shows the difference between the new and old fairing, should look pretty funky with the motor back in going along. New fairing is 1kg, old is 2kg probably from all the repair after I hit a Kangaroo a few years ago. By the time I make some alloy brackets to secure the upper part it'll likely end up as heavy, but be much more convienient, plus have better air intakes.
Re: Overhaul on the A65#212710 02/27/087:35 am02/27/087:35 am
Cylinders are nearly ready for plating. And I should be able to finaly assemble the bottom end now that I can fit the cyls and position the crank. This doesn't have much room between rods and piston at the pin, plus the bore centres are slightly closer, so it needs very precise crank setting so as not to have rods side loading the pistons. I cut the tops off the old pistons, which are the same dia, so it should make this operation easy.
Re: Overhaul on the A65#212713 07/23/0812:22 pm07/23/0812:22 pm
Getting the crank set in the right position took a bit of doing, its now got about .010" end float between main bearings with the outrigger bearing holding it inside that I hope. So these are the modified old pistons used to see where to line it up, the new pistons have much less clearance at the pin boss to rod so need to be as centred as possible.
The new cyl looking like it will work, just needs the plateing and the top surface set to get compression down around 10 or 10.5-1. The welding on the case just in front of the idler gear seems the location of the weakest point, it started cracking through as the motor tried to drive the crankshaft away from the head I expect, so the breather hole that was there is filled and a plate welded on.
Finally its going together, and the Cyls are plated, and pistons have sharp edges blended, compression should be down to about 10-1 but gapless rings may still make it hard to start if they prevent leak down.
Timing it might be fun because I never did know exactly where it was before, If the carbs are adjusted the same as when I took them off idle speed might tell me when it's close. I'll try around 32deg to start with as it will be less inclined to try taking my leg off.
The motor is pretty much assembled, with an unbelievable number of bodges to make everything fit, and I'm setting the tappets. What I have is alloy head and cyl and C/molly pushrods, the std alloy p/rods flex and lose a little power, and I don't seem to be able to get the bigger tubular alloy ones anywhere, and even then may have clearance problems if I did. The expansion rate of the alloy is different to the C/molly and the hot clearances will be different, does anyone know how much? Or have an idea of the hot tappet clearances for a std A65? Cold is 8 and 10thou and perhaps I should halve that or go even less, like 3 and 4thou?