MattG

Ha ha! I'm still after OEM.....cos whatever "artefacts" I get to in my life...I wanna make damn sure they're OEM ones! back!

Yeah, I know what you mean re. the timing wheel and then bringing the Meteor to spec. I don't have an old 460 jug to compare too, however! But on ope-forum mastermind has posted those degrees somewhere.... The thing that makes me most nervous with the above approach is the transfers, since ideally, I'll need a right-angle attachment for my grinding tool. Now I did see some RA dremel attachments on amazon, eg. (hmm... tried to embed the amazon link right here, but after about 5 tries I gave up fighting arbtalk's mental message formatting algorithm!!) but on the questions and answers there was much vagueness as to whether the above can be received by the flexidrive shaft. So I guess I'll wait for a bit longer for good 2nd OEM jug to "materialise".

Take a butchers at the pics in this thread: My Buddy Dave's MS260 and an AM vs. OEM Jug Comparison | Outdoor Power Equipment Forum They are not good advertisements for AM quality.....you get what you pay for! The QC on the intake port for meteor on post #4 is horrendous.

I'm bearing the meteor option in mind. But I'm curious about the differences in porting between the OEM and meteor. For example are the heights, weights, angles identical? You may remember from a previous discussion re. casting artefacts on the top of a head on a 200T to know that I'm somewhat of a perfectionist!! I'm not going to all the bother of putting together a 44/46 hybrid etc. and then failing to hit the max. possible with a reduced port areas. If the meteors porting figures are on the nose, then cool, else I'm continuing my search! thanks Matt

Yes, I know that they are rare as rocking horse sh!t, however......has anyone got a decentish 460 cylinder they want to part company with in exchange for local currency???

Yup, I'll certainly keep you updated.... I've just very carefully taken off ~0.5mm of the exh roof. Much trickier than my old Yammies (mine was air cooled too - DT175MX - cracking bike), and now the jug's all slapped back down with a slip of sealant (instead of the stock gasket). I'm gonna give it a final press/vac test, though I can't see why the base wont seal pretty nice as is, but just to be sure. I probably won't touch it for a little while now, plenty more things to do round here alas. But I'll get a youtube of her running when it's all good.

I think I'll be good I'm not trick enough to dare to touch the transfers, and the gasket delete will have increase inlet duration already. 10-4 on what you said re. the CR, however at operating revs. the actual cranking pressure will be different. I've done this stuff before like 25 years old on MX bikes, widening ports (in my humble opinion) is more contentious, since you can run into ring bulge issues. Experienced this myself, when I made my Yammy DT175's exh too wide. F**king blistering performance, but destroyed piston and rings every 400 miles!!!

I know what you mean on the safety thing. Even a small saw can kick back nasty on a misfire at start time. FWIW I always cold/hot start anything with the chain break on, I've got a pretty face and I sure don't want it scratching!! Well, the next job, is that given that I've lowered the cyl by 0.5mm by the gasket delete....the next thing is to raise the exhaust port roof by the corresponding value - I'm not after higher revs - just perfecting the specification of things as much as I can. And hopefully maximising the torque output.

A couple of piccies as promised: Firstly here's the setup rig to machine the squish band.....started on P80, then worked down to P240. Secondly, after a few minutes grinding, managed to rid the squish band of those stupid manufacturing artefacts, and hey presto, now have a proper squish.

Ha ha! You wanna try drop starting my 064 on a cold day, cos it aint got a decomp......so the 200 with raised comp will be a piece of p!$$ ! But yeah, getting squish right, also means more of the fuel/air charge will be confined to the actual combustion, and yes, thats the crucial detail.....not just a marginal compression ratio increase. Matt

I done the "machine the top of the dome" trick using a old piston with disc of emery stuck on top, as suggested by bmp01. Have to say, it was a lot easier than I thought, and I reckon I've got a pretty squish clearance without the base gasket now, rough measurements being between 0.45 and 0.55mm in the 4 different measurement points. Will try to get some piccies up in the next day or so.

Dude, Missus has caught some double-sided taped she reckons. I've got fine paper already, but I've requested that 800, 400, 240 is purchased, and I'll see how things pan out. 10-4 about keeping it clean!! I never ever want to repeat the exercise of my late teens, where not having any valve grinding paste, led me to mixing sand with grease, and unfortunately getting the odd grain between the valve stem and guide. You live and learn it seems Your comment re. "1mm from edge" Hmm..... unfortunately the crappy moulding extends right to the edge, so it will be flying on the seat of my pants type of work. I've done worse in the past - so I'll just have to play to cool. later fella

Ha! Yeah they are little sods to get "just right". I personally use my own version of the one in the manual for the L side of the tune, but seeing as I'm not up in a tree all day long, I'm probably not as fussy as some over the exact throttle response!

That's a good idea. Any thoughts for holding the paper down though? I'm thinking superglue, since I'll probably want to start coarse and work down finer. Do appreciate that those things you describe as "lumps" merely look that way when viewed on a screen, they actually protrude down no more than that thin ring, the very very outermost annulus - of about 2mm which you should be able to just make out by viewing my piccy. They are merely D-shaped bosses on the existing casting process artefact (for want of better terminology). The entirety of those things you refer to as lumps and that very very outermost ring on the dome, all do protrude down by about 0.15mm into the cylinder, repeating myself, into the available squish clearance space. Sorry for waffle! But yeah, the paper idea is a good idea - and I'll keep you posted. Matt

Finally, I found a 0.1mm (4 thou) thick flyer at work. Pinched it. And made me a replacement gasket.....with a razor blade and belt hole puncher as my cutting implements. Using this (instead of the stock gasket) should give me ~17 thou at the crappy periphery where those stupid bosses are, and about 26 in the area without that sh!te. Ta da!