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Post by GrumpyUnk on Apr 5, 2019 21:23:46 GMT -5
Just acquired a Super 9, not even sure of the year. Someone jammed the kick starter, and the battery was dead, but the price was right.
Took the CVT cover off, and found I could turn the variator with little effort. The kick starter spring had sprung free of the post, and jammed into the variator, so it appeared locked up.
Question is twofold: 1) I suspect low compression as it is easy to turn, though I can feel a little compression, so should I look for rings, a piston & rings, or cylinder piston and rings? 2) where to buy them.
It is the liquid cooled version. Is it worth putting any money into? I do not want it to ride, but promised my wife if she bought it, I would fix it, and she could keep anything she made. So, it is investment of my time & skills and her money for parts purchase.
Looking at older posts, the links I follow seem to go to nowhere or to 'new locations' that have seemingly purchased web site addresses and forward.
Who has Super 9 lc 50cc parts? Not looking for an upgrade per se, but want it to run well so someone who is into 2T's will want it. Should I pursue replacing the compression bits, or just sell it on as is?
Thanks inadvance.
tom
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Post by 190mech on Apr 6, 2019 0:16:31 GMT -5
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Post by tiny on Apr 6, 2019 6:45:16 GMT -5
Just be careful as the S9 LC and the AC are based off of 2 different engines so not everything is interchangeable particularly on the engine aide of things and don't be fooled exhausts between the two are not interchangeable. My friend that has worked on many LC & ACs and when i talked to him about getting one for my LC he assured me that they are different . Very minor but different.
But all other parts are interchangeable.
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Post by GrumpyUnk on Apr 9, 2019 22:07:13 GMT -5
If I get it, there is no compression release or any mechanism to make the compression seem inconsequential from the factory. I could turn the crankshaft with my fingers using the variator. Slight pssshh noise as the piston moved.
Took it apart, found a nice shiny cylinder with no apparent scoring. Rings were shiny, and I plan on checking end gap. I ordered some rings and a head/base gasket and await delivery. The pistons still show the machining marks with very slight indication of wear. The piston top is coated with carbon, but the cylinder head is very clean. Coolant was present until I drained it and made a continuing mess.
There was no rust on the cylinder walls, and the ports looked clean. Wanna see-a pic? Tell me how to post. Only other 2T I did much with was a string trimmer that was 30cc.. upped to 33 with replacement piston & cylinder. It is working fine. Circlip was a bear to get out. Big end seems tight and smooth. Little end bearing has no noticeable play and is smooth.
What can make one lose compression? Ring wear? There is no ridge on the cylinder after 24k km. Or could it just ave needed some oil on the rings?
tom
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Post by 90GTVert on Apr 10, 2019 6:13:12 GMT -5
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Post by GrumpyUnk on Apr 10, 2019 15:28:24 GMT -5
 cylinder head with not much carbon deposit  piston still sowing machine marks  othier side of piston  bore showing intake, I think.  looking down bore with light from flashlight  down the bore again  wrist ping and nedle bearing. Nothing has been cleaned, so what you see is what was there. Surface looks used, but no particular wear mark, smooth all the way around. The crankcase STANK of old gasoline turned to 'the new chemistry' of something... sour. Not looked at carb yet. Any guesses as to the reason for low compression? There was zero pop at all, and I never really felt the piston go past TDC. Hoping for worn rings. tom |
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Post by 190mech on Apr 10, 2019 17:55:07 GMT -5
It all looks very good!A possibility of rings stuck due to rotten gas and when you pulled it apart they freed themselves..I'd throw it back together with new gaskets and try it again..You could check the ring gap while its apart,but the piston shows very little blow-by...
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Post by GrumpyUnk on Apr 11, 2019 9:38:13 GMT -5
It was originally diagnosed as 'locked up' by someone, and had the kick start lever removed when I got it.
Is it actually possible that if some lube or solvent-type fluid had been drizzled into the spark plug hole that the rings would have sealed, and compression miraculously been restored? Is the ring tension that low? They just don't seem stuck. Thick, yes, but stuck, no. For such a small piston, these rings look as if they were made for a Maytag two-stroke from 1937. Okay, for a 1946 B&S 3hp horizontal shaft reel mower. Thick.
Nothing about the deposits on the cylinder head or piston crown? Anything I should watch out for if I take the carb apart to remove the deteriorated fuel? Any way to check the oil level as the light goes out, but I can't see a thing. Book says 20W20 two stroke. Recommendations? Do you clean out the crankcase if a bike sits for a while or just let whatever's there stay? It sure stank.
tom
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Post by jackrides on Apr 11, 2019 13:01:55 GMT -5
Cylinder needs to have the ports chamfered and to have a good honing then cleaning. Do the rings move freely in the grooves? If not, very carefully clean the grooves. The needle bearing has pits in it, replace it.
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Post by GrumpyUnk on Apr 12, 2019 8:56:51 GMT -5
Jack, do you mean the edges of the ports hit with a file so the rings can slide past w/o catching when you say the ports need chamfering? That makes sense. There is a difference of opinion about cylinder honing per a discussion on a turbo dodge web site. If using chrome rings, it seems, honing will create a surface that will cause the 'break in' edge on the chrome rings to seat quickly, giving good ring action from installation. Seems some makers add a tiny ridge of non-chrome that wears quickly to conform to the cylinder. The chrome rings being so hard faces, they need some abrasion to conform. Dunno what I am getting as far as chromed or not. The current rings seem to move freely, not rotate, but expand/contract when pressed without hangup or feeling 'gummy' or 'sticky'. I have not removed them, nor checked end gap as yet, given other projects. I will check the grooves and lands for deposits when I remove the rings. Likely will clean with a brush and carb cleaner or other solvent prior to re-assembly. I will examine the needle bearing more closely under magnification as what may be there is detritus from moving it around. At a casual glance, I did not see any pitting, but will be sure to check closely. We have had a lot of pollen, and that may be what is on the rollers as I never cleaned nor flushed the bearing after removal. Read here if interested: www.turbododge.com/forums/f11/f69/245224-cylinder-glaze-myth.html Leaves me questioning 'known' facts about honing. tom |
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Post by geoffh on Apr 12, 2019 9:23:09 GMT -5
You might be over thinking this if your just selling it on,I,d clean inside the crankcase with rags and degreaser rebuild it and check the compression with a gauge.the carb is easy to clean on a bench with wires drinking straws tiny implements,ect, to check every orifice is clear,set the screws to factory and get it running.
Geoff
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Post by jackrides on Apr 12, 2019 12:21:00 GMT -5
Yes, port chamfering is putting a small radius or angle on the top and bottom of the ports to be easier on the rings. I think really wide ports are safer with an angle, only a degree or two from vertical. Cratex rubber/ abrasive in a dremel tool works great. If using a file, use a very fine round or half round one. Hone afterwards, then Clean. Or; applying a Brush (brand) or ball hone first one direction, then the other does great also. Ball hones require their own lubricant (it's cheap) and a thourough cleaning with detergent, hot water and a cylinder brush to get all the abrasive down the drain.
The lengthly articles on honing will take a little bit to get thru, then the collective brilliance of 49cc Scoot will show the best path. I'm a total fan of Brush hones and procedures. The pamphlets on micro surface finish tell the whole story. A quick summary is like pulling a phonograph stylus (with only the tiniest weight) the length of the bore and measuring how much it moves up and down. (Millionths of an inch?) There is the bore surface! This is lab work and we learn from it.
Hones come in grit sizes like sandpaper and the 'valleys' hold oil and that's good.
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Post by rancevas on Apr 17, 2019 14:04:18 GMT -5
Alright, here we go. Most scooters can be turned over by hand, because as you turn it, the air passes through the rings creating less and less resistance. You can't really say much about compression when doing this. Although, when you will be putting the engine back together make sure that the rings don't align or face the exhaust port. This is very important. If this seems like your bike bikez.com/motorcycles/kymco_super_9_lc_2008.phpthen from what I can tell the compression for your engine should be around ~160 psi. You can't test it accurately if the bike doesn't start. It needs to be warm to do so. Because as you assemble all the parts, right, you will have to put oil on them. And that same oil will increase the compression giving you a false reading. So we will move onto that later. As you have disassembled the bike now, take a quick look with a flashlight inside the engine. There should be no debris inside. (just a preventitive measure) If I were you I wouldn't have dissasembled the cylinder just yet. I'd try other methods first. And yours looks in perfect shape! You can really get it going! 1. Check if there is spark. Put the cap on the spark plug and place it onto the metal parts of the engine. The threads must have a contact with the engine, since the engine is grounded. Connect a battery and give the engine a spin. If you can fix the kickstarter - use that. Battery is just an alternative. You will have to look for a spark as you turn the engine over. If you see it, move onto the next step 2. take a look at the exhaust pipe. You have it removed so check the airflow. A visual inspection of the silencer is also preferred. There should be no debris inside. 3. Check the airbox. Is the airflow normal? Is the filter all clogged up and nasty? Give it a clean! 4. Look for leaks around cylinder head and the cylinder head gasket. If you see something that appears to indicate a faulty head gasket - change it. Your cooling system is liquid. Was the coolant level low or normal? Was it contaminated with anything? 5. The carburetor. Have fun cleaning that, lol. There are bunch of tutorials online on how to do that, so I won't get into it. But don't take this step for granted. It's vital that the carburetor is in good shape. It sometimes takes even 3-5 times to clean it properly before it can get the engine running again. So, after doing all that try to start it. Note that a reassembled engine will take loads of energy to get it to start. so be patient with it. If it doesn't start - I'll move onto the next steps. Reed valves and all that other nasty stuff... ((Very important - If it ain't broke, don't try to fix it. I have done this mistake loads and loads of times... so, to get the engine running, first try the easy steps and then move onto the hard ones. Don't buy unnecessary shit until you are sure that it is important. Because fixing a scooter can quickly become a money-consuming black hole...)) Other than that, Some effort and motivation will lift that scooter off the ground. Good luck and report how it goes. |
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Post by GrumpyUnk on Apr 23, 2019 10:45:15 GMT -5
I am familiar with two stroke engines on outboards, chain saws, and various 'string trimmer or similar' applications. They all have a 'bump' when the piston gets up to TDC. You can feel the compression.
This one seemed to have almost zero compression, no where close to being enough to start. I did not even try it was so easy to turn over by rotating the variator.
I figured the rings were cooked as the coolant was still in the system, visible in the 'window' up front, and there were no indications of leakage. It smells like antifreeze, was green, and has that feeling, additionally, it does not want to 'wipe up' when some is spilled on the concrete. Thing wants to dribble and drip for days, it seems.
As far as my knowledge goes, the cylinder looks fine, the piston still has visible machining marks that have not been touched by wear, and you can see crosshatch in the cylinder wall. The rings that are installed don't seem to be stuck at all, and were aligned properly by the pin in the groove, as far as I can tell. I just thought someone may have run it hot, and de-tensioned the rings, allowing poor compression. When I had other two strokes fail, they all had scoring of the cylinder wall, and matching piston & ring scores. (dunno what I did wrong as always used proper mix and good lube. Too lean, likely) The owners manual said to 'adjust to highest speed attainable using the H needle', which I did, but after replacing the jug, have decided to turn the needle a bit towards 'rich' from the highest speed. I think they were run too lean.
Anyway, I have new base & head gasket from Taiwan, and will see if the ring set I got fits properly. Will also check ring end gap on the 'old' rings vs the new set.
I expect that the kick starter might need to be 'stood on' if the compression is good upon re-assembly. My practice is to liberally coat the wrist pin & bearing, cylinder, rings and piston with motor oil just before assembly, such that it would produce a blue cloud on startup. I want it LUBED. Makes things slide together more readily, anyway. It will have oil to improve compression.
Have not even looked at the carburetor.
How do you 'know' the oil injection is working? Book says 20W20 2-stroke oil for the reservoir. Any recommendations? The tube between the filter/airbox and the carb was in the storage bin. Exhaust seemed pretty clean(for a 2T) and I will blow through it using my shop vac to be sure it flows readily.
Pretty sure the Kymco CDI needs 12v to operate as I think they were all DC(anyone know for sure?) Kicking or using the starter is questionable with the piston & cylinder not attached to the connecting rod... so for right now, will skip that.
tom
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Post by geoffh on Apr 23, 2019 15:32:50 GMT -5
Tom,consider a first start up with premix in the tank it will be messy but it,s the only way to be safe,I can kick start my 2t in stocking feet but it,s already good to go.don't miss the reed valve and carb cleaning bit and attach everything before you try to start it.
Geoff
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