Not so fast, cowboy.
This is what it looked like after I had taken off the silencer can. I think you'll agree it looks pretty. Pretty awful.
The old studs (or at least the three that were unbroken) came out without a struggle. I expected to take off the nuts and then have to wangle the studs out afterwards, but in fact the nuts were so badly siezed onto the studs that the whole lot came out in one. So far, so good.
Unfortunately, the headers appear to have been welded in place. Not literally, but there is something seriously solid holding them in there. There is not a shred of movement in them, no matter how much force you apply. This meant (because of the way the headers fit around the frame) that I couldn't wiggle them away from the bike to get a bit of purchase as I levered them free. Out came Mr Angle Grinder (you can see that I had by this time get the bit between my teeth and forgotten about getting to work next week) and I cut the headers in two. The single part of the pipe then came away, and the left hand header almost fell off in my hand. Not in a good way - it was so rusty that a bit of wiggle broke it in two. I suspect that this is where the air leak that was causing all the backfiring was. The boss is still in the cylinder head, dammit.
So one side has nothing to get hold of, and the other has a few inches of rusty and rather too flexible pipe. The headers have a large boss on the top end, and this is firmly siezed into the cylinder head on both sides. I have tried chiselling them out, but to no avail. With my luck, the chisel will slip and I will chip the cooling fins. Broken cooling fins are a sure sign that a bike had been badly bodged in its past, and I really don't want to do that. Access for large and aggressive hitting instruments, as you can see from the photo, is very poor. It looks as though I will have to take the cylinder head off and take it to the workbench.
Bugger.
And in other good news, the heat shield on the bit of the exhaust that runs by your foot is not budging either. It's held on by two screws, but I have tried everything to shift them, fruitlessly. Big screwdriver, impact driver, impact driver and vice, heat + impact driver and vice, nothing. I will have to drill them out and find new ones. I need to do this to remount the shield on the new headers, but also because I want to give it a lick of black engine paint before I do. It should look good on the new stainless pipes.
Oh, and one of the brackets on the silencer can has broken off. Mechanics-wise, not a great day.
[1] Not in that sense. I have just broached a new bottle of 10-year-old Talisker, and very nice it is too.
That's pretty much the full set of "unfortunate"! Something I always curse, whenever working on Yamahas, is the way that nothing is ever quite accessible enough to do what you need to do. Well, that, and the incredibly poor quality fasteners that tend hamper any attempt at disassembling any part of the bike.
ReplyDeleteDefinitely looks like an engine-out job from here.
You have my sympathies on that one.
Part of the 'programme' for this bike is always using decent fasteners when carrying out repairs - a kind of rolling upgrade. It's not as bad as engine-out. I just need to take the head off. As it's an OHC engine, that means a bit of buggering about with cam timing and stuff, but that will be an interesting exercise in itself. And having the chance to have a look at the bore and valves will be quite welcome. Not all bad, but not quite as planned, shall we say.
ReplyDelete