Uh Oh. War & Peace type length alert on post.
Feel like a thread pirate on this but relevant info to initial post and lots of very interesting comments going on here - enough for several different threads!
Although I'm pretty sure too much coating material was removed, I'm not sure I have much of a leg to stand on with any sort of claim as I didn't measure the thing first, and it was pretty tired to begin with. I see the Ashburton replate outfit refer to a specific diamond hone machine. Apparently these type machines are very expensive - like $30,000 or so. Different thing to finish honing a newly replated bore to honing a worn one though. After finding a couple of in-depth articles, conclusion is a lot more to it than meets the eye. Seems to me the real advantage of a very light hone is to create a good surface for an oil film to cling to, ie not perfectly smooth. I think a light scuff would be OK.
I can't afford a re-plate or new jug so I'll just be trying to extract the max life out of what I now have. I can still get correct 0.055mm piston/bore clearance with bigger piston.
I was told it 'needed a hone to help bed the new rings.'
Really wish I'd gone with instinct now. Although it would certainly help I don't believe this is really necessary and here's why. I hate to admit this on here, but when I did the valves and rings on the KLX I made a stuff-up with (black ring) ring order (bum steer off US site thread is my excuse) I wanted to pass the bike to new owner in proper condition so I stripped it down and re-ringed it again. I'd run it in quite hard as per Mototune advice. The new ring seal faces were quite rough to start with - they came out shiny, after only an hour's riding. Seems as long as you get enough pressure on them, they should bed in fine. Rings are soft, bores are hard.
See photo of before and after hone:
I'm getting into the habit of making notes and taking photos when doing any significant work. Unfortunately no pics of bore after cleaning. My rough guess of hours on the bike was 100-150.
Bore was pretty grubby but the marks looked worse than they really were. Rings were pretty stuffed. The odd looking diagonal smear on bore at left of the before pic is beginning of me cleaning. There was definitely some varnish type glazing that was tougher to remove than the black stuff. The WD40 solvents and scotch-brite broke it down though. I kept going until I got a clean paper towell with white spirit. Main concern was quite a pronounced ring lip.
RE. larger piston. I think changing piston sizes without very accurately measuring the bore first probably not a good idea. I'd actually priced up a telescopic guage and mic for the job but decided not worth it for amount of use (Hindsight now 20-20!). The bore guage the engine recon guys used was a very fancy thing - like a tripod with telescopic guage on the end. Another to be aware of is although my bore measured up nice and round, there is always more wear around ports. 4 strokers don't have to worry about this. There are bunch of ports all the way round my cylinder. Hardly any bore surface at all at bottom of stroke. With straight edge against the light you can see the extra wear curve at port height.
I'm big on warming up engines first too. Apparently the thermostat on the EXC opens up at 55 deg, so when you can feel heat on the radiator tops this gives you an indication of where engine temp is at. Was curious about what engine clearances might be at operating temp so doing an 'oven experiment' on this at the moment. Results pending...
Well put Reckless Re blue printing being 'made' not produced. Mass production processes and product design always involves compromises. I've found a couple of pretty big nasties on mine that weren't imediately obvious - previous owners had missed.
RE Carb slide stuck open: Ha. I had the same thing happen last time at the Sandpit carpark. Scared the shit out out of me. Not a good look.
Apologies again for the mega-post. Just hope this might save others a big pile of time and money. "Say No to Honing" 'T' shirt on order.
Reply With Quote
Originally Posted by kezzafish
..you cant have hot girls in your area ..they keep telling me they are in my area..whats going on ??
Bookmarks