So Close!...
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I know, if the weather is adverse I feel obliged to test myself against it
️I cleaned out the bowl of my carb last night before I went out, specifically the pilot jet because it’s not been starting or running great at low revs. It’s like a different animal again! Great starting, smooth revs all through the bottom to ‘top’ mid range. I’m surprised how much of the rev range is actually affected by the pilot jetting!
When I removed the pilot and blew it through you still couldn’t see a definitively clear hole (it was opaque) I had to use a thin, kinda serated wire to clear it till it showed properly to the eye. I don’t know if it’s a hard deposit build up or a ‘gluoopy’ oil residue? But something seems to be regularily obscuring the jets bore. Maybe cause I’m running pre~mix? (Castro Racing) The filter on the fuel tap looks great, also I’ve got a good new filter in-line between the tank & carb. I don’t really understand its cause
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This post is deleted!
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Hoop! Talking to myself!
Bike chewed up a piston ring last night. Just lost power and started clattering, killed it like a heat seize with the clutch. Took the exhaust off tonight and peeked into the exhaust port. One ring down and a lot of shiny new scratches on my (previously pristine) 3MB cylinder head
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I had to nurse it 30 miles to get home to safety. So I’m guessing if any of it dropped down a transfer port I’ve lost the crank and cases as well. Oh well, shit happens…Can’t help thinking that there are loads more worthy candidates out there than me tho’
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@SpookDog wtf! I have never seen someone have as much bad luck with these engines as you.
All I can think is that you are caining it everywhere and you do lots of mileage. But in the 12 years of ownership of my bike I have only blown the head gasket after I used a cheap one after my bike got stolen...
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It feels like bad luck for sure, but the head gasket problems were just my ignorance and previous boners putting wrong jets in the wrong carb. My head problems are totally solved now…
I’ve never had a two stroke or any other engine have a ring let go though. I’m guessing it happens at the exhaust port where the rings have to bridge the biggest ‘void’. My barrel/piston was a bit worn and egg shaped judging by the ‘slap’ movement in the piston. So it’s my own fault. I was really hoping it would see me through till the spring tho! Oh well
happens!… -
No, I didn’t. They were new rings from pjme and they slipped in ok. I just did a quick visual with them in the barrel to make sure they weren’t doing anything extreme
I was just hoping it’d be ok cause I rarely go above 6k and never above 7k (I still don’t know what a late 88-90 engine shoul rev to!!) Just killing time & cruising up them miles till spring
There’s no mystery, I’m just feeling sorry for me~elf
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Nah, if I hadn’t of gotten nearly 6000 trouble free miles I could agree with you. I knew the barrel was oval shaped when I first fitted it. Like I said it was a bit ‘slappy’ You could feel the excess movement in the front to back at TDC, side to side was OK. I just wasn’t expecting anything catastrophic!
I just find it really helpful to document my ‘happening’s’ in this thread for future reference. I used to write it down on all sorts of cardboard, pads & things but always end up misplacing it, let alone keeping date of things…
I need the data to work out the problems. At the moment I’d love to know if my engine RPM peaked so low normally or whether I have a miss-balanced crank that won’t let it rev to 10k+ -
Ditto my first rebore. It’s normal wear, front to back. There is no side to side pressure on a piston/barrel…
I have to make a list of bearings for a rebuild now. I don’t know whether to get the crank rebuilt and balanced though. I wish I could find somewhere that could check the balance…
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The top ring retainer pin came loose and worked it’s way out and up (in a bounceabout kinda way
) into the head and through the exhaust port. So luckily both rings are still intact and never made any shrapnel down into the crank 
. Just scratch (lol!) 1 head, barrel & piston…
Fitting a donor tomorrow I hope…MerryXmess!…
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Like I said before, I didn’t measure, just a quick visual check in the barrel. It’s a jap Mitaka piston. I don’t blame the brand, it’s just a mechanical join between the aluminium piston and the brass pin that can fail in any brand piston, just bad luck
The piston had been overheated (judging by the black inside the crown) before I even brought the top end second hand. Couple that with possible vibration problems?…I think the rings were RIK from PJME…
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Day 1: 40 mile shakedown has shown no problems. Barrel & piston is a lot better condition/fit than the previous one, but by no means new. Choosy Beggars and wotnot
Rehoned the barrel before fitting so am being gentle with the revs to let the rings settle. Nothing above 6000rpm… -
These are the first pics of the Romeu Henrique stainless steel expansion chamber and tailpipe/serviceable muffler that I brought in Dec. I will take pics when it’s fitted to the bike…
Also below, there are the progressive fork springs. Shown next to a standard spring…
The 27mm hex tool (1/2 inch drive) that I got for £25 to dismantle the fork bottoms without drama!
fitted to a 1/2inch extension bar (2 needed to reach inside fork)…
With the fork bottom inners. The inners undid with very little effort…
One of the fork bottom Allen bolts came out eventually. I’d already nearly rounded off the head before I removed the inner with the 27mm tool bit, so it needs replacing…
The second one is still stuck in the fork bottom as you can see. The head is rounded off badly and needs heat and banging out from inside, which is now possible since removing the inner with the 27mm tool bit. It’s corroded into the fork bottom because of the dissimilar metals and the tiny gap between them…
I’m waiting on a new blowtorch since my old one ha given up the ghost!…
I’ve gotten new bottom bolts, seals and bushes (top & bottom) to go with the springs. So the forks should be as good as new when done and powder coated…
you do serious mileage on your bike. I haven't ridden any of my motorbikes since July. Fired up the DT yesterday, took a few kicks but akk seemed well.
I wonder whether the rings were out of spec then?
