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Discussion in 'Airheads' started by bmwblake, Mar 26, 2012.
Full marks for creative use of sludge in order to show a condition to viewers.
sometimes art is worth suffering for.
On the headlight bucket, those holes can be welded up. The big hole just cut a piece of metal to fill the hole then weld it in place. Might not be perfect once you grind down the excess, but that's what bondo is for. really just time, it would be pretty easy to do.
i forgot to mention that i picked up a used bucket with the switch and all internals included. i was able to get it for cheaper than sourcing all the parts i needed for the ignition switch/cover/etc.
.....speaking of impact phillips... I am re-doing a Yamaha XS650 with my son, and the clutch on that guy has BIG phillips head screws (most would replace with allens), and since I don't have a hit-it-with-a-hammer impact, I improvised with my $39 Home Depot air impact wrench... I drove the nearest-fit socket onto the top of the big phillips 'driver, and used the air impact while pushing down hard....worked slick as snot on a doorknob......
this weekend i made a lot of progress and found a good bit of unhappy news.
it seems that someone forgot to put in a wrist pin circlip on one side of the right piston. any thoughts on repair methods would be appreciated.
i'm not sure if it's related but there's also a good bit of slip in the connecting rod on that side.
in other news, i was able to get the front end apart and remove the steering head bearings and races. i welded beads on the races but they didn't contract enough to fall out, so i added enough material to the welds to get a punch through from the opposite side and was then able to drive them out.
bucket and wiring off:
so now i'm down to the frame and need to determine what i'm going to do for paint, etc.
on a side note, while cleaning up the bottom of the center stand with a grinder to fill in some holes, i managed to hit my left index finger with the flap wheel. it now looks eerily similar to the gouge in the right cylinder.
safety third. i'm renewed my policy on wearing gloves while grinding.
Cool resto! Is the blue framer in the background a Montessa Cota 247 Trials bike per chance?
Looks to my eye like you will need to bore that cylinder out to the next oversize... given the pitting and scoring.
Boring to next oversize for the cylinders will be the minimum I believe. It may need taking to the second size. Those pits look pretty deep. What is the line we see in the bottom of the cylinder? The circlip was completely missing? Those pits were caused by water I think. If saving the cylinders by boring is possible they will have to have new, or another, set of pistons. You might do better with another pair of cylinders all together.
About your comment, "i'm not sure if it's related but there's also a good bit of slip in the connecting rod on that side." Do you mean the rod big end seems loose? After this much investigation and all the damage you have already found you should take the rods out. They can be checked for size at a machine shop and when reinstalled use new bolts and new big end bearings. When they are out you will be able to see the condition of the crank at the rod journals at least.
You need the special rod bolt tool to remove them.
Everything is related. Was water in that cylinder? What does the other side look like? If water got in the lower end of the engine there may be damage to the crank. you need to check this.
the line in the bottom of the cylinder was caused by the wrist pin moving outward from where it should be. a circlip on one side of the pin was missing and i didn't find it in the pan. i'm guessing it was left out on assembly by the last guy working. there was a bit of rust in the cylinders but nothing that made me want to toss them other than the giant scrape from the wrist pin.
there is front to back play in the rod big end on the right. i plan to remove it and get new bearings. no evidence of water in the bottom end.
i was hoping to keep this an r50, but looking around for parts there are way more r75 and r60 parts. that makes sense when you look at how few r50 bikes were produced.
if anybody has an r50 top end laying around give me a shout.
I have an R90 so I think there are more R50 parts and 900 cylinders are rare. I guess it's a matter of one's view point.
it's a 79 bultaco sherpa. it's waiting in line for some attention. i've been ignoring it for months.
this weekend i pulled the front forks apart and was met with the nastiest smelling oil i've ever encountered. i replaced the fork seals and the rubber bits in the bottom of the forks. here's what they had become
i need to drop the springs back in and add some oil and the new fork boots and the forks will be done.
Uuuggghhh, those flap wheel burns HURT like hell...I've done the same thing.
It's good to get fresh oil in the forks. If they seem to not always go up and down easily then you may have to check more but the fresh oil and some parts is a good start. I just wanted to say that the old oil always looks like that. It was in there too long but nobody changes it often enough.
i have a used set of barrels, pistons, heads coming my way.
i also ran into an old friend this weekend that happens to have a media blaster i can use. that answers the question of how to best clean the frame and all the other painted parts that have corrosion.
You didn't happen to buy this bike from Stagehand did you?
find a local sandblasting joint. buy 2 bags of play sand from the local lowes/home depot. pay the guy $20 + 12 pack of bud. Blast down to bare metal.
check for cracks.
strive to prime and paint before further corrosion sets in.
That cylinder with a single scratch in it also looks like it is quit pitted. Just from the photo I'd say it was not usable as is.