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JR, just a note to again thank you -- used your expertise to test my thermostat (http://scooterdoc.proboards.com/index.cgi?action=display&board=250cc&thread=2151&page=1#13422), and it passed with flying colors.

Given how much blue gunk (darn that cheap coolant), I have a question. I have found crystalized gunk at each point where a hose meets the engine (at the thermostat, and the impeller, and the cylinder block). Any easy way to test if said gunk is also gumming up the innards of the radiator?

On a wholly unrelated note, I read your exchange with mccalli about cooking -- my dad was a food and wine writer and a chef, and I still chuckle when I recall first going off to college and discovering that my roommates didn't know how to make a basic bechamel sauce. I kid you not, my first thought was "Dude, didn't you have a dad growing up?" I thought all dads taught their sons how to make a souffle, etc.

Took the cylinder block to a local auto shop that hones engine blocks, and the owner thought it made more sense to buy a new cylinder block. He looked at the head and valves and said they looked fine, so it looks like I'll get this:

.chinesemotoparts.com/index.php?main_page=product_info&cPath=112_135&products_id=2166" rel="nofollow" target="_blank">.chinesemotoparts.com/index.php?main_page=product_info&cPath=112_135&products_id=2166

Total rebuild (block, piston, rings) for 108.95 (free shipping). What I can't determine is how long it will take -- anyone have any experience with this company?

Been busy doing other things, but picked up a gallon of Berryman carb and parts cleaner (with basket!) and will try to soak top half of cylinder head tomorrow.

Have tried repeatedly to pull cylinder block off, but no luck. (Since piston was at TDC, scooteraddict, there were no cylinder walls exposed to get oil onto...piston was flush with top of cylinder block).

Finally decided to rotate crank at by turning variator nut...piston moved down, and I stopped turning when the piston reached bottom, and then tried to pull head off. No go -- whereas with piston at TDC the cylinder block would rock, with piston at botton no movement at all. When I then continued moving the piston, the whole cylinder went up with the piston, so clearly piston is sticking! I will try to remove it later, but now that most of the interior cylinder wall is visible, I did smear a bunch of oil in it, and will leave it overnight.

I have hope the cylinder isn't cracked, and that what explains the rust is the for the last (nearly) three years, it has sat in my garage with no cylinder head cap nuts on, thus allowing cheap Chino coolant to leak between the cylinder block and the head, and pool on top of the piston. It's surely possible that after 130 miles the head cracked, but here's hoping...

Thanks to all...I have been tap, tap, tapping away and have the entire cylinder block rocking... it doesn't appear to be sticking at any corner, but no matter how hard I pull, it won't move up off the piston. The timing chain doesn't appear to be the problem. Again, I have rotated the piston without a problem, so I am surprised it is putting up such a struggle.

I have been using the very online helix manual you pointed me to, damin, but it never crossed my increasingly cloudy mind to check it for the proper gasket setup. Duhhh....

Closer examination of the removed head gasket reveals that it is indeed one gasket, that has some sort of coating that is separating from the metal, on both the top and bottom of the gasket:



Anyone seen this before?

Finally, if I can't get the cylinder block off, is there any harm to trying to rotate the piston to free up the head, or will that cause major problems with the timing when I put it all back together?

This thread is over on Scooter Doc, but to get JR's opinion (and all other interested parties), I am posting the latest help request I have over here. If this isn't appropriate, my apologies...I just need all the advice I can get. To see the full thread, go here:

.scooterdoc.proboards.com/index.cgi?board=250cc&action=display&thread=4057" rel="nofollow" target="_blank">.scooterdoc.proboards.com/index.cgi?board=250cc&action=display&thread=4057

Okay, after getting the electrical sorted out, I tried to start the bike, and I noticed a leak near the head gasket. Old owner had replaced rocker arm, and when I eventually pulled off the cylinder head cover, I discovered he had not replaced any of the cap nuts on the head bolts. I finally pulled the head, and what I found isn't pretty:

Here's the top of the cylinder itself:



Most of the crusty stuff looks to be old radiator fluid mixed with gas (and perhaps some of the diesel fuel I dumped in there a few weeks ago to try to clean things out). What's on the cylinder head itself is fairly pliable, and can be wiped/scrubbed off.

(1) My immediate question is this: what sort of solvent should I used to remove this gunk? Would Gunk carb cleaner be apprpropriate? And second, is there any sort of scrubber that I should or shouldn't use? My worry is whether taking some fine steel wool to this would mess up piston head...again what's the right product to use.

Second question concerns the head gasket, which appears to be in two parts -- a metal gasket and a non-metal one that is clearly disintegrated:



(2) I purchased a set of replacement gaskets, and I have both a metal and non-metal head gasket. Do both go on after I get this mess cleaned up?

Finally, here's the underside of the cylinder head itself:



Two final questions...notice the bluish gunk clogging up the thermostat. This gunk is also is various places in the water jacket surrounding the cylinder, and clearly needs to be cleaned out. Again, recommendation on a cleaner, or a process to use?

I will take the thermostat apart and check it (for now it won't come out of the cylinder head...it wiggles, but won't pull out. I gather it's because that bluish gunk is deep in there as well.

Again, to summarize:

(1) Best cleaner(s) to use on cylinder head and piston, and scrubbing gear that won't damage any components?

(2) Best cleaner(s) and procedure to use to clean out the water jacket? Is it simpler to clean what I can see, then put it together and flush the #%*&#* out of it? (Though please note the bike has yet to start, so flushing may not be an option at this point)

(3) When re-installing head gasket, do both the metal and non-metal gaskets go on?

Many thanks in advance...