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Post by GrumpyUnk on Apr 24, 2019 9:32:24 GMT -5
I got my new rings, and they seem correct. I placed the old top ring into the bore, and squared with the piston. The tips of the ring ends are modified to have clearance for the locating pin, making them very narrow. Is it the same procedure for those tiny ends of the rings as 4T ring end gap checking? I did not measure, but it seemed both old and new had similar gaps. The old ring seemed to have a lot less spring against the cylinder wall when compared to the new ring. The new rings each have a black wipe(paint?) on the outer diameter. Nothing to differentiate top from bottom, so how do you know what is the top? Left is top, thinner, right is second ring with tension spring Note the black paint/ink wipe on both ring edges. Doesn't mean a thing to me. Anyone? tom
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Post by GrumpyUnk on May 22, 2019 9:36:52 GMT -5
Finally got the head and base gasket and tried fitting the new rings just to feel the 'friction' level of the new rings. Ohhh. Those rings are tiny. They don't want to go into the taper, and will slip past the groove in the piston if you are not super careful.
I am looking for hints on how to get them in place without breaking. I have tried tilting the piston and twisting it so the rings are in a position where I can see the 'pins' and ring gap, and then trying to push the piston down into the bore to get one ring compressed.... doesn't seem to want to go. I did check ring end gap, and the new rings are at about .010", the old closer to .020", with the Kymco outer wear limit being .040" per the manual, (from memory) but I need someone who has done 2T rings on one of these to give some pointers... Have looked at youtube, and got a bit, but it just seems the rings squeeze out of position and don't want to compress. Any takers? tom
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Post by geoffh on May 22, 2019 15:15:24 GMT -5
Tom,I have done my piston a few times,I assembled the piston on the con rod then slid the bore over the piston using quite a smear of oil on both to help.it is tricky try a few bench fitting runs,ensure every thing is in its correct orientation or the rings will catch in the ports.keep at it.
Geoff
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Post by SMALL CC TEK on May 22, 2019 17:56:48 GMT -5
You should check that cylinder it's 39.0/39.025mm limit is 39.05 then check that ring gap 0.10/0.25mm limit is 0.40 just see where it falls that will give you a decent look at the condition of the motor Change the water pump seal if it sat more than 6 months or so ... That oil pump works good if that o ring at the top is in good condition and the wide open arrows line up properly . That oil pump will only support a stock bore don't trust it with a 47mm just be on the safe side if i was you ..
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Post by GrumpyUnk on May 22, 2019 17:57:57 GMT -5
I did a 32cc(?) string trimmer the way I have seen, the way you describe. BUt. This piston & rings just seems to get loose and not want to go into the grooves. Get one side lined up, in the groove, start to push the piston into the bore, and it feels 'jammed', so I look and examine, finding another section of the ring is out of place, not even in the groove, just out there ready to get broken off. One vid suggested placing the piston at an angle, and then worrying the rings around the 'pin' and then pushing into the bore. It just doesn't want to cooperate. Service manual 'install rings, install piston into the bore' more or less. The rings don't even want to go between the two skirt extensions, an inch or so away from the cylinder 'ring ramp' which would encourage the rings to slide into place. I don't see any way to do this with the piston on the connecting rod, and expected to put the piston into the bore, and then install onto the wrist pin. Just doesn't look as if it can be done the 'normal' way, piston on the rod, and slide the cylinder over the rings... etc. Is there such a thing as a ring compressor for a 2T. tom
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Post by geoffh on May 24, 2019 15:20:58 GMT -5
They do make "small' ring compressors and I was experimenting with with a soda tin and hose clip contraption,I think there is something wrong maybe the rings do not suit your piston,hard to help,do those tapered ends close over the locator ,looking at the picture one end of the taper looks longer maybe they have a top and bottom??
Geoff
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Post by geoffh on May 24, 2019 15:27:55 GMT -5
And once I managed to fit the piston in the barrel on the bench then attached the assy with the wrist pin but fitting the clips was a nightmare,I should mention it is possible to fit the piston upside down or the ports in the wrong spot,just basic mistakes easily made.
Geoff
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Post by GrumpyUnk on May 26, 2019 7:41:30 GMT -5
From trying a test fit, there's no way I am getting the rings into the bore while the piston is attached to the connecting rod. Well, getting the rings into the bore in one piece. I'm sure I could get them installed if I didn't mind them being in multiple sections. The way these rings fit, there is so much ring extended out from the groove that you can look between the ID of the ring and the OD of the piston. Get that into the installation 'taper' of the cylinder, and I am not so sure the ring would/could move into the groove without a LOT of help. The 4T ring and piston assemblies just need a little coaxing, and the rings didn't seem to stand out so much from the piston as these rings do. They do fit into the bore with a proper ring gap, but getting them there in a groove in the piston seems to need a technique I am not aware of. yet. tom
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Post by geoffh on May 26, 2019 9:56:26 GMT -5
I think you have a miss match of parts,I would call time and if you can buy a barrel with matching piston,garage art is a good use of old stuff.
Geoff
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Post by aeroxbud on May 26, 2019 17:32:41 GMT -5
I would take the piston off the crank. Then try a test fit into the head on the bench. When you have more room, and can see exactly what is going on. If you can get it fitted correctly a small way into the head. You could refit the piston to the crank still inside the head.
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Post by GrumpyUnk on May 27, 2019 12:10:11 GMT -5
Geoff, these were cited to fit the Kymco Super 9 LC piston, along with the Honda Dio, and another Kymco version. The fit the bore with a .10 mm gap, which is at the tight end, and fit into the grooves properly. They just are BIG in diameter compared to the piston, so sort of hang out more than expected. I have another set of rings that are supposed to fit. I guess if worst come to worst, and I cannot fit them, I should be able to just get a standard kit. tom
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Post by geoffh on May 27, 2019 14:30:35 GMT -5
Tom,if it helps ? When I fitted the rings to my piston it,s close you gotta squeeze them just enough to go on feels like they will snap if you use more pressure if your rings are"easy" to fit to the piston I still think they are miss matched,remember even honest vendors only have the info they got and tend to believe it,s correct.
Geoff
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Post by GrumpyUnk on May 28, 2019 9:47:52 GMT -5
Well, I gave it a test-run. Got the piston down between the two 'legs' close to the tapered area. I had marked the piston with Sharpie to indicate the position of the locating pins. That way I could make sure the ends of the rings abutted and were not rotated out of place. I lubricated the rings/lands/grooves with motor oil, with some going down all the way around the piston, and slid it a bit more while using fingers to compress the top ring. It fit. I pushed it into the bore a little more, and again used fingers on the second ring. It was a bit more apprehension causing, as it was a bit harder, and seemed to be hanging up. I rotated and inspected to see if there was a problem area, and the ends were located to the pin, and wiggled and pushed a bit more. It slid into place. There is a LOT more force needed to move the piston in the bore. The old rings looked fine, should have worked, and the cylinder wall was in what I would have said was excellent shape. But. There was no compression. Rotating the variator, there was no 'pop', no spot where it was harder to rotate than any other spot. My impression was there was no compression, and it would be likely impossible to get running. I have other 2T engines in trimmers, blowers, and chain saws. They ALL have a 'pop', even the one I think is on the way out(which I cannot get started..). This Super had no pop. I am considering assembling as is, even with the wrist pin retainer being difficult to install. I just don't want to try to do this holding the cylinder(it gets heavy, and starts out heavy - cast iron with a water jacket). It can't hurt to try that way, and if it does not seem possible, I can always go back to trying to slip things together the other way. I did slide the piston up to TDC, and then back, and it had no 'hang' of any kind on the ports(that I could detect). I did use a file on the 'horizontal' edges that the ring could have hung up on, just making sure to take off any 'feather edge'. I am going to lube up the cylinder/piston/rings and slide it back and forth a few times to see how much friction there is. As I recall, it had about the same as a 4T piston, perhaps a little more. Thoughts? Cautions? Suggestions are all welcome as I am not any sort of expert with 2T engines. On the 4T, I have used RTV silicone, wiped using a finger, on both sides of the base gasket, figuring a very thin layer of silicone, 99% squeezed out when the head is torqued, would provide a good, definite seal. I planned on doing the same. I have cleaned up the bottom of the cylinder head to the point that there are 'stain' gasket traces, IOW, not perfectly clean as from the factory, and figure that should be good enough. I do not like the stamped head gasket, but that's what I have, so I'll use it. I had to knock the head free when I took it apart, but it did not take much. There was no evidence of coolant leakage or combustion leakage. tom
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Post by SMALL CC TEK on May 28, 2019 11:59:00 GMT -5
Just my two cents here ! Do you have the rings in the right positions? One is square and one is beveled take a look beveled is the top square is the bottom... That will make it tight if to you have put them upside down the expander goes on the bottom.
The super 9 rarely ever overheat only when modified so your clutch locks up at 4 ,5 grand then they get hot that little red light stays on ! lol
Here is a tip ,i noticed in your cylinder the rust deposit from the coolant . If you want that cleaned up you can buy a bottle of Eagleone wire wheel cleaner it's a acid designed for consumer use ,and probably the strongest retail one you can buy. Just spray it in the passages let sit for minute or two rinse and repeat a few time works on outside as well will clean any aluminum up nice like new . It wont hurt the cylinder because it was designed for chrome and painted surfaces .. I would clean it up cause you don't want that rust scale making it's way to your radiator if you can help it ....
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Post by geoffh on May 28, 2019 15:32:01 GMT -5
Tom glad you cracked it,as long as your shooting for the moon a smear of sealant on the base of the barrel is what I used,watch out for those pin clips tricky to fit and catastrophic if loose/not seated properly.I lost a couple due to Sharkey hands and noviceness ,after some practice and thought I tied some fine thread through pin and cut a groove at the edge of some needlenose pliers to hold the clip as I fitted it,well worth masking the crank off so if they do "ping" into the wild blue you will know they are not snuggled next to your innards.
Geoff
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