Time for an engine overhaul?

[anjames]

Hey guys,

I got a 2000 GZ250 for _free_ which had been sitting for 3yrs and didn't run when I got it. I'm finishing a PhD in mechanical engineering soon so I figured that working over a motorcycle would be a good test of my skills (or lack of them). Since then I've unsiezed the piston (thanks to Mystery Miracle top cylinder oil), cleaned the entire fuel system including the carb with ethyl alcohol, flushed the brake line, sanded rust off the forks and replaced the fork seals to fix a leak, lubed the chain and replaced the oil regularly. I've never gotten around to adjusting the valves, but it seemed to run fine so I wasn't too worried about them. One of the only problems is that it has a moderate oil leak from the head gaskets (both the upper AND lower ones along the cylinder) which over time covers the case in oil and requires occasional cleanup and topoff. The bike and I have gotten along nicely for the most part, and I've happily driven it to work the 5mi along the coast almost every day since getting it running (maybe 6mos).

Yesterday on my way home on the freeway I'm pretty sure I blew the rings. I don't typically ride on the freeway, but I have some friends who I brew with on the occasional Saturday and they live about 20mi down the freeway, so who knows if it was the freeway driving (at speed 65mph), or if the rings were just ready to go and I was unfortunately on the freeway. I had a sudden (brief) loss of power and after that the bike started blowing LOTS of blue smoke (ie burning oil) and revving uncontrollably when not in gear (but not delivering a huge amount of power when in gear). There is also some oil collecting at the end of the tailpipe. When cold it will run ok (with smoke) and not overrev, but as soon as it warms up it just revs through the roof and I have to modulate the kill switch to keep it from blowing up at stop lights. I can only guess that the overrev is due to the oil getting past the piston, vaporizing when the engine is warm, and detonating so that even though the carb isn't putting much gas in, the oil burning is enough to rev the motor up? Anyway while I was able to get it home, it's obviously not a safe ride in this condition, so since I got the bike for _free_ and I'll have some time on my hands while finishing my thesis, I'm planning to take the top end apart to replace the rings and head gaskets which should keep me busy for a while.

So my question to those of you with experience in these things is: are there any hitches I should foresee in this job? Are there any magic tricks to getting the head apart and back together without too much grief?

There is a 'special tool' listed in the service manual for adjusting the valves, which I'm pretty sure is some combination of a hex wrench and a square wrench, but I don't know where to get one. Any tips on adjusting the valves?

Also, since the head gaskets and the rings failed, these are obviously weak links in this otherwise reliable motor. I would be very happy to replace these bits with the best quality parts around, so are there more robust replacement parts in the aftermarket than the OEM ones?

I noticed that the bolts attaching the pipes to the head are pretty rusted, so I'll probably order a new set of those as well just for good measure, but I've heard that these can break off if they're too badly rusted, in which case it's enormously difficult to remove the broken off ends and the motor might be considered a bust (though I could probably drill them out and re-tap the holes if necessary). Any tips for getting these out in one piece?

Also, should I bother cleaning out the pipes beyond just draining any remaining oil out of them?

Thanks! Alex