Ah yes, young Metcalf, let's talk about that MZ. I seem to remember that you spent an age Rally-prepping it then it blew up on its maiden test run.
And then you went silent on the subject :-)
Please tell more.
GC
Yep, all ready for the Elefant and it seized on the way back from Scarborough!
80 mph laid on the tank and the back wheel stopped. It's funny, I can remember the speedo (driven off the rear wheel) showing zero as all my old MX skills came flooding back. I grabbed the clutch, so I only left about 1000 miles worth of tyre on the A-64 (plus my lunch). Having pushed it a mile and called the RAC I gave it a test prod and the ****** fired up. Called the RAC back to cancel the cavalry and rode home.
I got the head off and found nothing except a bit of detonation marking in the soot on the piston crown to I put it back together. It's now done 2000-odd km with nothing more than a resealed exhaust nut, an extra dose of oil in the first tank of petrol after the seize and taking the bar muffs off.
I'm stumped as to why it seized. Two ideas are left after colourtune tests, chop tests, test runs and so forth. One, the clutch was slipping (I heard it), because of the bar muffs. I think if correct, 80 mph was about 12000 rpm but the stroke pump (as set by the throttle position) was only ready for 9000 (this is probably not good). Idea two, the exhaust was leaking which (I'm told) by some devious means upsets the back pressure in a stroker and makes it run lean and hot. Less stuff in the way to hold each new charge in? Can't get my head round that to be honest, too much going on at once in these strokers, but it runs way better after the firegum treatment. It made a lovely noise blipping through the gears with the exhaust basically open though (Yes, it's not big or clever, only fun, unless you live on my route to work)!!!
So, I don't know. I got a spare piston and barrel, so I can just wait and ride and see. It can't be that bad, it'll still do 85. The journey through my biking childhood continues. I love the light and revvy way it rides, it's just a pity they don't do blue stroke oil anymore, the red isn't the same.
Andy "I love the smell of two stroke in the morning" Metcalfe