Last time I posted on this project, it had reached a bit of a blockage. One or more of the pistons was stuck because the piston rings had rusted to the barrels.
So far, they've had about 4 weeks of soaking in engine oil, a day of working WD40 in and picking out debris, a couple of days of soaking in white vinegar, then another week of soaking in WD40.
None of those produced any movement at all. But they allowed me to get quite a bit of rust and debris out, so it's fair to say that each different treatment has done it's bit to help work towards a solution.
This evening, I tried a couple of new things;
On the left, my favourite rubber mallet and a piece of the stem cut from a privet bush savagely murdered by evil honey fungus (it's the absolute scourge of our garden, we've lost so many trees and bushes to it). On the right; Plusgas. It's a bit like WD40 on steroids, a kind of aerosol penetrating oil with a strong rust-dissolving action.
I had to chop the stem a bit thinner with my trusty axe so it would fit nicely down the cylinder bores, and needed to make sure I cut it long enough that I wouldn't accidentally smack the studs.
You'll see a lot of YouTube videos where people use lump hammers and metal mallets to do this job. I chose to use a rubber mallet because bike engines are more delicate. I wasn't aiming to apply a lot of force, it was more about jolting stuck bits loose than hammering them all the way out.
It took about 15 minutes of squirting Plusgas, a bit of gentle tapping, and huge amounts of wiggling to get the barrels this far up. I also stopped every couple of minutes to use a soft size 4 artist's brush to sweep out the debris that was falling down from the stud shafts. Realistically, I know some fell into the crankcase and will have to be dealt with, but I'm pretty sure I got 90% or more of it safely out of the way.
This is after 30 minutes. By this stage, it was mostly about the wiggling ! I found the secret was to work each side in turn, hooking my fingers under the fins and pressing down on the studs with my thumbs. But I only did a few millimetres at a time, to avoid twisting it too much. The brownish red you can see on pistons 1 & 4 is rust being washed off by the Plusgas; I tried to mop it off with kitchen towel before it dripped into the crankcases.
After nearly one and a half hours I'd got to this point. Number 1 piston is already free - I had to be careful when wiggling to make sure I didn't hit it and cause damage. For no reason that I can work out, the last centimetre was the hardest !
And they're off !! Just in time, too - the light was just starting to go. I packed all around the bases of the pistons with kitchen towel to stop anything dropping into the crankcase.
Although I need to check and measure them next time, the actual pistons are in far, far better condition than I expected. I have a horrible feeling the piston rings may be beyond saving, which is a shame because they're around 拢140 a set (拢35 a piston, but it's probably a good idea to do all of them at the same time). I've got a spare set of pistons and barrels, so it'll be a case of working out which are the nicest or closest to being usable.
The barrels are frustrating. Three of them could almost certainly be usable with a light honing. Number 3 on the other hand..... just yuk.
I might give it a hone for a laugh and see what it looks like. But more likely it'll be a case of looking at the spare barrels, measuring them up and seeing if they'll work with either the refurbished pistons here or the spare set, whichever looks better.
But despite some of the awfulness and knowing I'll have to go into the crankcase and clean any debris that's dropped in, I feel like getting the barrels off is a huge step forward in this rather leisurely-paced project, so I'm happy 馃榾
