KymcoForum.com
General => Technical | How To => Topic started by: jprestonian on June 11, 2010, 02:26:11 AM
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... and I think it's the head gasket (http://kymcojones.blogspot.com/2010/06/cucumber-slumber.html) (a real shame, since we just replaced this in May, 2009!).
My new gasket arrived today (ordered because I've been bartering a bit with the shop for work). It is NOT cardboard. It is black, and appears to be some type of synthetic material, or perhaps metal...! And it is two-layered, and has what appears to be two brass grommets holding the two layers together. Could they have further determined that the gasket they sent last year was also somehow inadequate, hence the change...? Or [fill in the blank]...?
Any ideers, gearheads? How 'bout pointers on getting the chain tensioner right when I tackle this on my own, as that's what the guy last year goofed on, causing me another five weeks of downtime.
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...damn, jpress..heating again???
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Yeah. If I keep it under 50mph (which is a lot of my normal riding, really), I can go two weeks between burping sessions. At that point, the gauge will read full HOT for a minute or more when idling in traffic, and I just don't wanna let it go like that very long.
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..you reckon there is a "flatness" issue with your head??
..that the gasket can only compensate for, for so long a time??
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..you reckon there is a "flatness" issue with your head??
..that the gasket can only compensate for, for so long a time??
It's a thought, sure, but the mechanic said he used a feeler gauge to check it, and it was well within spec... or so he said. Of course, he didn't get the cam chain tensioner right, causing the chain to break a week later, so...
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...i know, from your posts, that you trust your guys at the shop....
..however, if you keep blowing head gaskets, then there MUST be a flatness issue...
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...considering that there isn't a temperature or coolant flow issue....
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Well, this would be the second one, and the breach is on the inside (towards the water jacket), this time, as opposed to the outside (causing a massive oil leak, last time).
I'm thinking because of the changes in the gasket they supply that they may have identified a materials and/or design flaw that they're trying to correct via the "upgraded" gasket. Read my post over there, and see what you think. I'll try to get a photo of the gasket to include in the next day or two, but this new one looks a LOT more serious than the last one.
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...considering that there isn't a temperature or coolant flow issue....
Well, there is a temperature issue -- hot exhaust gases building up in the cooling system will do that. :) Pockets of gas get trapped near the thermosensor at times, causing the thing to go off the scale. Overall, it may not be all that hot, though. Still, you gotta get that crap out of the cooling system. Leaving it in there can cause cavitation on the pump impeller, beating it to death, over time, etc. Plus, you just don't wanna have to deal with it all the time, right? I mean, this is a quality product, reportedly.
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..once you remove any "air" that would create cavitation in a closed loop system, then it should be gone forever..unless there was an opportunity for the introduction of more "air"..
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..once you remove any "air" that would create cavitation in a closed loop system, then it should be gone forever..unless there was an opportunity for the introduction of more "air"..
Right -- and what I'm theorizing is that I'm burping most or all of it out every two weeks... but it's coming back, 'cause it isn't air. Instead, it's gases being introduced into the water jacket by a very small breach in the head gasket.
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..i agree...it's the same effect...and that leads back to craftmanship of the two surfaces...
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What happens to the level in the reserve tank, Jpres? Does it go up, down, stay the same? I mentioned once before I thought it COULD be just a leak in the hose that goes to the reserve tank. My theory goes like this: Engine warms up and coolant expands and sends a little overflow to the reserve tank. Then, normally, when it cools after shut off, that same amount of fluid gets sucked back into the main system by the vacuum created when the coolant cools and shrinks. If there's a tiny air leak in that hose, it could be sucking air back into the system instead of the fluid it sent to the reserve tank.
It would have to be such a small leak as to allow air IN but not coolant out. But since that tube doesn't have pressurized coolant in it, you'd never have coolant come out -- just air IN.
The possible air leak could be in the hose itself or at one of the clamps on either end.
OR: Same thing might be caused by a faulty radiator cap!
I'd sure check these things before going for the gasket.
Good luckk and I sure hope it isn't the danged gasket!
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..hoolandr is right...have you replace any (all) hoses?
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..hoolandr is right...have you replace any (all) hoses?
I haven't. Maybe I need to do a chemical test to detect exhaust gases before I decide to replace the head gasket, hm?
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..maybe so, i guess...you'r getting a small amount of air /gas into your coolant system that makes the coolant boil...
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Hoo -- I'll do that. Does the overflow tube extend almost to the bottom of the overflow reservoir? That would make sense, in the physics-sense, I reckon. I'll make sure to check, but I seem to recall the overflow being half-full, every time...
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yeah, I remember you said you did do a pressure test on the radiator and it was ok. But that doesn't rule out the reserve hose or, for that matter, the cap.
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Wow, these posts're coming faster than I can keep up!
Well, if my little theory is right, I guess the reserve tank level would go up a little bit over time, though, maybe not.
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..maybe so, i guess...you'r getting a small amount of air /gas into your coolant system that makes the coolant boil...
I don't think it's so much a "boiling" problem, as that would tend to make it spew coolant into the overflow, and possibly out the puke tube -- none of which has happened, ever. A small bubble of air/gases in the system however would tend to explain the temp gauge's behavior -- not throttle-dependent (unless riding at high speed, continually), and even when it hits full HOT when stuck in traffic, a hop up and down on the seat can cause the needle to plunge 20% or more (perhaps causing the "bubble" to travel along, rather than sitting right by the thermosensor).
That's why I was theorizing on it being a tiny breach of the gasket. When I burp it every couple of weeks, I never have to add more than 3-4 oz. of coolant back into the system. Right now, if it is a gasket leak, it seems to be very, very small.
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YEp, and that bubble could just be air with coolant steam in it.
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..i admit, i need to research your scoot's system before i could give a better educated guess...
..all these theories seem relevant...just pinning down the cause....
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Hoo sez:
YEp, and that bubble could just be air with coolant steam in it.
I appreciate everyone's thoughts on this, and I will make sure the reserve tank is where I expect it to be (around half full) before I go tearing the jug off this mother. ;)
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..no doubt....check the integrity of th hoses too, i reckon...
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Yes, the hose goes into the reserve tank below the level of the fluid. I'd even check the nipples where the hose attaches at either end for tiny cracks. A good ole visual and manual inspection is in order! If not outright pre-emptive replacement.
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Worst case scenario: I now have a very kick-ass lookin' head gasket (that I hopefully don't need, just yet). ;)
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...good luck jp....but your scoot's history in this matter preceeds...
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Would be nice indeed to have a beautiful, not needed head gasket to hang on the wall. :)
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..i got a brand new, 1 mile used, kevlar belt with a nice 1/8th inch deep groove in it on my wall..
..dammit...
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LOL :D
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..live and learn...
:o
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...i'm going to bed...sid's already at work...
..peace ya'll!!
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Sid's about to knock off and go scootin'. Oh, and top up that thirsty little tank. ;)
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UPDATE: Overflow reservoir is more than half-full, so air is not being reintroduced via that route, I think it is safe to say.
Not wanting to pay for a kit that will chemically detect unburned hydrocarbons in the coolant, I think I should simply plan to replace that head gasket. Given that I have a new one (which IS metal -- opened the glassine envelope just to get a better look/feel), it's the only way to be sure.
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...it should be an upgrade, and maybe your troubles will end there...
..bite th' bullet j....
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Ok, been waiting for your update, Jpres. Hey, now, did you check the hose? That's where the fault would be -- not the tank. I'd take the hose off and look it over VERY carefully. Make sure the clamps are on tight too.
The tank being "over" half full lends support to this. It would go up a little during each period between burps.
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Ok, been waiting for your update, Jpres. Hey, now, did you check the hose? That's where the fault would be -- not the tank. I'd take the hose off and look it over VERY carefully. Make sure the clamps are on tight too.
The tank being "over" half full lends support to this. It would go up a little during each period between burps.
Both mechanics I consulted on this found it pretty inconceivable that any leak that could draw in the quantity of air that is being introduced would not also be at least leaking some coolant. Plus, with the radiator cap open, topping it off as the "air" leaves until it becomes hot enough to require shutting off the engine (so as to keep the coolant from belching out), I can never get all the "air" out. Shut it off, top it off, let it cool down, and repeat the process, and there's always more "air" there.
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Well, I hope the new gasket does the trick for you, Jpres. Sorry for your problem. Say, would you consider doing a little experiment? When you've got it all apart for the gasket work, don't do anything to the hose or it's clamps. Then, if still a prob after the gasket replacement, we might zero in on that hose again. At least we'd have a better idea if it IS that at that point -- process of elimination.
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No way! I'd have to beat myself with a stick! :)
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Right -- and what I'm theorizing is that I'm burping most or all of it out every two weeks... but it's coming back, 'cause it isn't air. Instead, it's gases being introduced into the water jacket by a very small breach in the head gasket.
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I jumped ahead on the posts for this. Exhaust gas will not be the hot spot at the sensor. It cools the second it hits the coolant. The trouble is (in my opinion) the coolant is being displaced thru a leak in the head gasket, and being burned in the normal cycle. When you shut down the scoot the coolant is still hot, and under pressure. It is very likely the back pressure of the coolant is enough to "clog" the leak. That way you will have air in the system, and not be losing any real level in the bottle. I agree w/ slinger that the head MUST be checked. It is easiest to have a machine shop inspect it, and have a few thousandths milled off. Feeler gauges won't cut it. Inspect the gasket for ANY discoloration at all. That will pinpoint the problem. Anything else seems unlikely to me. The new design on the gasket may be enough in itself, but I would have the head checked. If the old gasket shows anything on the cylinder side you may want to have that squared as well.
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Got Big Red Ugly back, today. I've only ridden it about 15 miles, but so far, so good. No overheating, almost no vibration, whatever (very noticeable!), and I have a new drive belt, Dr. Pulley sliders (20g) and a Stebel horn, now.
It's been in the shop over six weeks, and I won't tell you what caused this issue. All I can say is that I got the repairs at-cost, and that was a whole lot less than I would have otherwise paid. I have an awesome dealer, and I can't say that enough! Even through the repairs, I always had a loaner scooter, every single hour of every day. Who does that, in this day and age?
Even so, there's a chance that we're not done with this. I'll update my blog (see .sig) as time passes. Right now, I'm gonna go run it up the interstate to see how Dr. Pulley has affected the power band, and to see if I can cause it to overheat. :) Let's be happy for now.
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..i wish you the best, jp...
..i know this has been a thorn in your side for a while...
:-\
..it's also good to hear of a GOOD dealer story...
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Got Big Red Ugly back, today. I've only ridden it about 15 miles, but so far, so good. No overheating, almost no vibration, whatever (very noticeable!), and I have a new drive belt, Dr. Pulley sliders (20g) and a Stebel horn, now.
It's been in the shop over six weeks, and I won't tell you what caused this issue. All I can say is that I got the repairs at-cost, and that was a whole lot less than I would have otherwise paid. I have an awesome dealer, and I can't say that enough! Even through the repairs, I always had a loaner scooter, every single hour of every day. Who does that, in this day and age?
Even so, there's a chance that we're not done with this. I'll update my blog (see .sig) as time passes. Right now, I'm gonna go run it up the interstate to see how Dr. Pulley has affected the power band, and to see if I can cause it to overheat. :) Let's be happy for now.
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Is there a difference now that you have Dr.P?
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Is there a difference now that you have Dr.P?
Oh, sure -- 0-50mph is like being shot out of a cannon. From there, it takes longer to get up to top speed, which has been slightly reduced (http://kymcojones.blogspot.com/2010/08/stress-test-ii-scottsboro-blues.html). So, I suspect the stock rollers are like 24g or more.
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and started to be concerned about the local constabulary. ;)
..I HEAR Y'!!..
..i wish i had that seat on my ppl 50....
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It's been in the shop over six weeks, and I won't tell you what caused this issue. All I can say is that I got the repairs at-cost, and that was a whole lot less than I would have otherwise paid. I have an awesome dealer, and I can't say that enough!
I know this is an old thread, but my P250 has a similar issue and I would love to know what fixed the problem with this scoot.
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Well my 09 P250S has been in the shop for a month and they cant figure out the issue with the over heating.
It has a new thermostat and the thermo sensor works fine. No leaks, radiator holds pressure.
They filled it up again and it keeps over heating, even though it is pumping coolant. Anyone have any thoughts? I am shocked the dealer couldn't find the issue.
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Your cylinder head is warped. Have it machined/milled flat, put it back together with a new set of gaskets. DO NOT OVER-TORQUE THE HEAD when reassembling!
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Is that what happened to yours?
Anyway I can tell if that's the case before I disassemble?
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Also, is it the head that needs to me milled or the head and cylinder as well?
Does this change the compression or stroke clearances after milling? Maybe I should install two head gaskets to keep the spacing correct...
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Is that what happened to yours?
Anyway I can tell if that's the case before I disassemble?
1.) That's the working theory, at least;
2.) You can test the radiator contents for exhaust fumes. There are kits that contain a chemical that will change color to indicate the presence of exhaust gases in the cooling system -- I do not have any first-hand experience with this, but several mechanics have described this to me.
3.) (in answer to compression, stroke, etc. in other post) -- Good questions. I'm guessing buying replacement head & cylinder is the only way to be sure, but I'd ask a machinist or very knowledgeable mechanic who rebuilds small engines.
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Two head gaskets are a bad idea since sealing between gaskets is always a problem. It depends upon how much is milled off to get the head flat. The old-timey hot rod engine builders used to put dabs of kid's clay on top of the piston(s), torque the head back on and "bar" the engine over by hand then take the head off and inspect where the valves squished the clay. Shiny spots at the thin part meant the valves probably would hit the piston. The usual fix for that was to mill a "smile" on the piston top to clear the valve(s).
Karl
PS: I must say that Jeff and Wild are the most patient and forgiving men to have put up with this issue without killing someone. I think this has all gone WAY beyond asses and elbows time to be solved.
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1.) That's the working theory, at least;
2.) You can test the radiator contents for exhaust fumes. There are kits that contain a chemical that will change color to indicate the presence of exhaust gases in the cooling system -- I do not have any first-hand experience with this, but several mechanics have described this to me.
3.) (in answer to compression, stroke, etc. in other post) -- Good questions. I'm guessing buying replacement head & cylinder is the only way to be sure, but I'd ask a machinist or very knowledgeable mechanic who rebuilds small engines.
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Ok, I will plan on testing the vapors in the coolant for combustion fumes.
If its a negative result I will assume issue with radiator or water pump
If its a positive result I will assume a warped head/cylinder.
Sound reasonable?
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re: the hoses,. a hose on the suction side could be collapsing at high rpm.
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re: the hoses,. a hose on the suction side could be collapsing at high rpm.
Maybe, however it still overheats at idle.
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1.) That's the working theory, at least;
2.) You can test the radiator contents for exhaust fumes. There are kits that contain a chemical that will change color to indicate the presence of exhaust gases in the cooling system -- I do not have any first-hand experience with this, but several mechanics have described this to me.
3.) (in answer to compression, stroke, etc. in other post) -- Good questions. I'm guessing buying replacement head & cylinder is the only way to be sure, but I'd ask a machinist or very knowledgeable mechanic who rebuilds small engines.
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JP you fix your 250S yet?
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Sorry for your troubles. Long post, here's some thoughts:
1. The dealer is weak at trouble shooting - this is normal.
2. Don't guess at whether the head / cylinder jug is warped test it with a straight edge. Basically a perfectly straight ruler on edge laid against the cylinder head. There are fancy gauges but this is a start.
3. Pressurize the radiator with a tester and see if the needle falls under pressure which indicates a leak.
4. Compression test dry and wet - provides good basic info about possible leaks - head gasket, valves, total max compression dry/wet (adding a squirt of oil to the cylinder provides a temp seal).
5. Leak down test - look it up, it should have been done and should catch a leak from a warped cylinder / head.
6. Most likely exhaust gas is getting into the coolant. Consider taking the scooter to a small engine builder - have them tear it down, measure the parts - or send to a machine shop to test if the parts are in spec then they put parts back together if good and replace any if bad (out of spec).
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The head is in a shop right now for mill work. They are going to remove .002 from it, which is .05 mm, which is the variance the manual calls for oddly enough.
I found a chip in one of the coolant ducts in the head. The shop tech told me it was a scratch? If so no clue how it got there considering I removed the head myself.
Anyway, I will get a new gasket and re install the thing. Hopefully that will correct the issue. I dont know if I should pull the cylinder or not? Now would be the time if needed.... Anyone know?
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Shop said head was warped, they took .002 off the head, that's about .05 mm like the manual calls for.
Should I have the top of the cylinder checked as well now that the bottom of the cylinder head is fixed?
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I have also removed the cylinder, it was warped somewhat. About .0015 according to my feeler gage. I am going to take it into the cylinder shop today to see if they can hone the top .0015 off it. I will then use a brand new head gasket and head gasket sealant to fill in any gaps or missed low spots.
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Shop was offering to take another. 002 off the cylinder. I declined. It was not as warped as the head thus I didn't want to take that much off. I also am afraid of changing the compression ratio on the bike, so the less materiel removed the better. My local kymco tech told me you could get a copper gasket that is + .002 thicker than stock, but you have to custom cust them out, and I dont know the thickness of the OEM head gasket. As such I ordered a brand new cylinder head gasket and honed about .001 off the cylinder with 600 grit sand paper, just to ensure it was flat. I can go into detail on this process if anyone wants.
So to review,
cylinder head - wrapped by .002 - cylinder head shop took that much off and make it flat again.
cylinder - wrapped by .0015 - i honed .001 or so off it to make it smooth and flat again, really just removed the high spots.
head gasket - replaced with a brand new one.
All coolant is out of the bike, I have also drained all oil. I will start re assembly tonight and advise on progress and how she does once it start it back up for a test idle. Be sure to add coolant and oil to bike before you start it up again! Also, I am slightly nervious about the cam timing and cam chain tensioner, I need to be sure to get them installed correctly as to not bend a cylinder head valve.
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JP you fix your 250S yet?
Mine was a P, not PS.
I sold it for scrap.
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Well thats not good to hear.
update for all - scoot is not put back together yet. I will let you all know how it goes.
Mine was a P, not PS.
I sold it for scrap.
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Well after machining the cylinder and head to flat again the scooter has the same problem again.
The only thing I noticed was hot water getting to the radiator but no warm coolant getting out. Maybe the radiator is clogged or has blockage. Anyone know a way to test radiators for pressure and flow of coolant?
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no chemicals added to the antifreeze instead perform a compression test and report the numbers then perform a leak down test.
the compression test will show how much compression the motor is makingnwhich is a factor of piston rings the valve seated properly a top dead center which involves your timing chain and of course the head gasket. This is a fairly easy test to perform and when you do the wet test as you can read about online.
the leakdown test can be done with or without a gauge. basically with the motor at top dead center you put compressed air using an air blower usually with a rubber end that is shaped like a cone you put it up against the Pistons you pressurize it then you listen and look for leaks from three different places:
1. carburetor or throttle body if you have fuel injection - intake valve not seating properly.
2. Exhaust - this indicates a problem with the exhaust valve not sitting properly.
3. air bubbles in the radiator you want to remove the radiator cap- perform this with the engine warm so the thermostat is open so air doesn't get wrapped around the engine block.
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Well after machining the cylinder and head to flat again the scooter has the same problem again.
The only thing I noticed was hot water getting to the radiator but no warm coolant getting out. Maybe the radiator is clogged or has blockage. Anyone know a way to test radiators for pressure and flow of coolant?
I have removed the radiator and run water though it, it comes out well enough. However I am not sure what I should be compairing it to? I will try my best to flush it, then put it back on and see. I will also remove the thermostat to ensure coolant is getting to the radiator, hopefully doing these two things will stop the overheat message I am getting.
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It is usually a vapor lock issue. It's been the same on alot of kymcos.
Easiest way is to remove the TSTAT, and toss it. That will improve the coolant flow enough to expel the air. I just did a 250 2 days ago.
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Anyone know a way to test radiators for pressure and flow of coolant?
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Two tests for the radiator:
1. pressure test - a small pump like to pump up a basket ball is used to apply pressure. The system is sealed and the pressure should hold steady but if it begins to drop there is a leak for sure.
2. Flow test: remove radiator and pour water with the garden hose in the top and it should rapidly come out the bottom. If there is a delay allowing water to build up and overflow then there is a clog.
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I removed the thermostat last night and overheat problem is gone. Kymco part# 19300.
I am a bit angry with my shop, as they told me they removed it and tested it, and it was good. I had a heck of a time removing it, the bolts were on like they never had been removed. I will replace thermostat and see if it keeps on working, but it seriously looks like the thermostat wasn't fully opening after my initial coolant change. Debris must have gotten into the unit after the drain/refill and damaged it.
In short - if you change your coolant and then the bike overheats, pull thermostat first! Don't listen to the shop technician and rebuild the motor top end like I did!
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I removed the thermostat last night and overheat problem is gone. Kymco part# 19300.
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In short - if you change your coolant and then the bike overheats, pull thermostat first! Don't listen to the shop technician and rebuild the motor top end like I did!
For What Its Worth (FWIW) The Grandvista 250 and certain other brands / models of scooters have super tiny passages where it is extremely difficult to get the air out after a coolant change. My local dealer confirmed this. I changed my coolant in the GV250 and ran it with the cap off to let out trapped air until the fan came on twice! But I still overheated once I drove on the highway! I then needed to do 3 or 4 more burp sessions to get all the air out. Since that time everything is back to normal - no over heats in 4K miles.
I don't recommend changing the coolant on the Grandvista for several reasons:
It is harder and takes more work than any car or motorcycle that I have ever owned and you risk damaging your motor or head gasket with an overheat.
You will introduce an air pocket that causes the engine overheat even if you follow the instructions in the book exactly. This happened to me after I changed the super dark green factory coolant on my 2005 GV250 @10K miles. I ran the scoot with the radiator cap removed to allow air to escape and reach full operating temperature - twice! I got on the highway and 8 min later all 5 bars were lit up and blinking on the temp gauge!! Not good!
Coolant is capable of lasting 100K miles and most scooters have much less than 12K on them. You might want to change the coolant if it has never been done AND your scoot is 15 years old or more.
Dark Dark Green - remember, the dark green color does NOT mean the coolant is bad. It comes that way from the factory so you can see the level in the coolant bottle.
If you insist on changing the coolant:
EZ method - Look up the quantity in the system and remove about 1/2 by pouring it into a container then measure it. Now fill up with new coolant. Next year or so repeat. While you don't change all the coolant or "flush the system" you DO refresh the chemicals and PH balance.
Correct full method:
As suggested users on this forum and modified by me.... Loosen one bolt from the thermostat and wire brush the threads to remove the factory Loctite - aluminum threads and a steel fine thread bolt - not a good combination and easy to strip threads! Consider lubing the threads and reinstall. Repeat for all other bolts. The reason is to make sure you are able to loosen the thermostat first! Now drain all coolant. Now add just enough coolant to insure that the engine block has coolant, reinstall thermostat. Fill the rest of the way and run the motor with the cap off to allow air to escape.
Rock & lean the scooter side to side (like throwing over on its side) to get more air out. My dealers mechanic said this is how they do it! Run scooter to full operating temp to ensure the thermostat is fully open.
Drive the scooter around the block and keep an eye on the temp! DO NOT DRIVE ON THE HIGHWAY or a long distance from home. The coolant is very sneaky the passages are so tiny air gets trapped and once the motor is running at 70%+ it gets hot then overheats! Expect to have several air expelling / burping sessions with you scooter before ALL air is truly gone.
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Glad to hear you got it Wild. Long road to a short end...
Great post Bios!
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Two tests for the radiator:
1. pressure test - a small pump like to pump up a basket ball is used to apply pressure. The system is sealed and the pressure should hold steady but if it begins to drop there is a leak for sure.
2. Flow test: remove radiator and pour water with the garden hose in the top and it should rapidly come out the bottom. If there is a delay allowing water to build up and overflow then there is a clog.
Thanks Zombie. Now it's my scoots turn to overheat at ~ 21,500 miles. Only time I had an issue was when I changed the antifreeze. Today in ~ 87 degree temps on the highway i noticed 3 / 5 bars lit - usually runs at 2 bars unless it is really hot out. On the way home I noticed 4/5 bars and briefly 5 blinking bars / boxes. Checked coolant and it was not low, also coolant in the reservoir was only lukewarm. I think I will remove the TSTAT aka thermostat. Will update the forum with results.
UPDATE: I removed the thermostat and it took a while to warm up but still overheating. I rocked the scoot side to side to expel air with radiator cap off. The radiator does not seem to be very hot.
UPDATE: 07/25/2017 The problem comes and goes. Around town short rides no problem. But 8 miles + on the highway sometimes I see 4 bars instead of two. On the way home same stretch of highway no problem - the normal 2 out of 5 bars. Could there be a clog in the radiator? Also, last time it was reading 4 bars I could hear the fan running.
UPDATE: 08/12/2017 Solved? a few days ago I ordered the OEM headgasket on ebay for $15 including shipping (thanks to Sig for suggesting ebay for parts). Came in a few days. Installed the headgasket per the manual (wow big job ~ 6 hours total time!) and many things were left out of the manual such as unbolting the engine top mount to push the motor back so the head would clear the metal frame bar the the seat rests on, removing the carburetor studs and tilting the sprocket to get enough slack to get the timing chain off the sprocket and finally how and when to remove the lower chain guide. I took pictures of the procedure. I reassembled and to my amazement the motor started right up. Added coolant but the problem remained. Today I removed the front plastic and opened up the radiator and it was at least 1/2 empty. I drained the system flushed with the garden hose and refilled with water and test ran it. No overheating. I drained the water and refilled with clean coolant. Running perfect, for now. I suspect the head gasket allowed exhaust gas to enter the system and displaced coolant ( I saw coolant from the hole on the bottom of the scooter from the radiator overflow). Also, the head has signs of coolant leaks around the motor. However, as is often the case no coolant was in the oil and no oil in the radiator.
Also, the radiator inside from the little I could see after removing the large side hose was spotless like brand new even after 22K miles.
UPDATE: 09-14-2017 No overheats in about 500 miles. Mostly runs at 2 out of 5 bars. The test... Full throttle (I have a throttle lock) for 5 miles on the highway mostly climbing a long grade @80F outside temp. Mostly stayed at 2/5 bars and hit 3/5 but then fell back to 2/5. Got off the highway and lots of idling at red lights - 2/5 bars. I consider the problem resolved.