KymcoForum.com
Scooters - 50cc => People 50 => Topic started by: Ricfratt on April 29, 2020, 03:51:08 AM
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Hello, I'm new to this forum and to scooters but I just picked up two Kymco People 50's, a 2004 and 2005 (supposedly). They won't start. I got one to spark and get fuel but compression is low 75-80 psi. Figured I'd check/adjust the valve clearance before doing anything more drastic but I can't for the life of me figure out where to adjust the valve clearance/lash.
I've searched dozens of sights and watched every scooter youtube video and cannot find this specific engine. I've torn everything off and still cannot find the valve cover or where to adjust the clearance.
Any helps (pics) would be greatly appreciated!!!
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They make this model with a two-stroke engine?
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Couple of pictures would be cool - if it's standard 139QMB-type lump it's not all that obvious
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They make this model with a two-stroke engine?
Yes. It appears the People 50 came with both 2T and 4T versions.
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Couple of pictures would be cool - if it's standard 139QMB-type lump it's not all that obvious
Looked up images...four bolt valve cover... what is not obvious?
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Yes it's a 2-stroke and I'm generally familiar with car engines and it may be obvious and I'm just clueless but where most scooters seem to have the valve cover on the front of the motor this one has the spark plug. Pics attached. So if anyone can point out the obvious to me it'd be greatly appreciated!
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Yes it's a 2-stroke and I'm generally familiar with car engines and it may be obvious and I'm just clueless but where most scooters seem to have the valve cover on the front of the motor this one has the spark plug. Pics attached. So if anyone can point out the obvious to me it'd be greatly appreciated!
Okay. 2-stroke so there are no valves to adjust and therefore no valve cover - only the head. Compression is way low. I'd remove the head, slide off the cylinder and check the cylinder, piston and rings for clues. Very simple to do. How many miles on these things?
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Thank you, so I'm not crazy. Anyway they only have about 1800 miles but have been sitting a number of years I think. Pulled the head and the top of the bore has black charring but haven't dug further. So a top end rebuild, worth the trouble? Found this on eBay.
https://www.ebay.com/itm/fits-Kymco-People-50cc-2-stroke-engine-50cc-cylinder-rebuild-kit-/233089583639 (https://www.ebay.com/itm/fits-Kymco-People-50cc-2-stroke-engine-50cc-cylinder-rebuild-kit-/233089583639)
Thoughts? Thanks for all the responses.
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You need to examine further. Slide the cylinder off. You may need to tap with a mallet. With cylinder off you can really see what you have. Maybe the rings are stuck or something simple like that. I wouldn't spend any money just yet.
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It doesn't seem too bad to me, rings are free, no major scoring, etc. Here are a couple of pics:
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One more.
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At this point I think we need someone who's better at this than me. Kinda hard to tell anything from these pictures. Looks like a lot of discoloration of the piston below the lower ring. Is that right?
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Thanks eamartin, appreciate your help. And yes the piston is pretty discolored so maybe getting. Blow by and rings are bad?
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Guessing it may be varnish from being a 2-stroke oil-fuel mixture. Guess I'll try and see if the bore is in spec and re-ring.
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To check the piston rings properly you actually need to remove the rings carefully from the piston, slide each loose ring down the piston sleave for about 5 mm, and take measurements of the ring gaps with a fueller gage. Unfortunately I have no idea what size the ring gaps on these scooters are suppose to be.
When the ring gaps are bigger than prescribed specs, the engine will loose compression at the ring gaps.
It will also make sense to hone the piston sleave with a honer.
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I cannot offer much help....except I see in my Kymco Super8 2T service manual that the maximum ring end gap is listed as 0.40mm. Seems like a place to start. I imagine there are "rules of thumb" for this.
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Thanks scooterfan, I'll check the gaps tomorrow. So the kit to rebuild the whole top end includes, piston, rings, head, etc. and is less than $70. So before I continue down this road a couple of questions, 1) what else could be causing compression loss, 2) is is worth getting the upgrade (big bore) version?
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Thanks scooterfan, I'll check the gaps tomorrow. So the kit to rebuild the whole top end includes, piston, rings, head, etc. and is less than $70. So before I continue down this road a couple of questions, 1) what else could be causing compression loss, 2) is is worth getting the upgrade (big bore) version?
On 2 stroke engines I think a loss of compression can only be caused by:
1. Ring gap too big.
2. Piston sleave wear, (look for a ridge at the top of the sleave where the upper ring is located when the piston is in TDC position) or deep scratches at the piston walls.
3. Clogged ring grooves.
4. Broken rings.
5. Cracked, or damaged head gaskets.
6. Warped cylinder heads.
7. Loose cylinder head bolts.
8. Holes burnt in piston due to excessive heat.
I think it might only make sense to go for a new kit once all possibilities (mentioned above) have been eliminated.
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So tried to take some measurements (not the greatest tools) and the ring gaps seemed large. The top ring (smaller one) was .4 and the 2nd was bigger still. Manual says:
Piston ring end gap (top/second): 0.10 / 0.25; Service Limit: 0.40
So guessing top end rebuild is in order. Any thoughts on going ahead with a bigger bore kit or stick with stock?
I just hope this is all it needs or these "free" scooters are gonna start to cost me. ;D
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So tried to take some measurements (not the greatest tools) and the ring gaps seemed large. The top ring (smaller one) was .4 and the 2nd was bigger still. Manual says:
Piston ring end gap (top/second): 0.10 / 0.25; Service Limit: 0.40
So guessing top end rebuild is in order. Any thoughts on going ahead with a bigger bore kit or stick with stock?
I just hope this is all it needs or these "free" scooters are gonna start to cost me. ;D
What are the mileage on these scooters ?
Two stroke engines run hotter than 4 stroke engines. I noticed on the photos that these are not “forced” air cooled engines - whitch made me think these engines will run extremely hot. Specially at high RPMs, at speed, and due to the “hidden” location of the engine.
Maybe you should get more mileage from the engine if you can get more air flow on the engine somehow ?
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Maybe before you make the jump to a new top end of big bore kit from ebay you should check out some of the youtube vids from the scooter performance shops? I know scooterswapshop and rolling wrench denver talk a lot about aftermarket pistons, cylinders and heads (and sell them to from their online shops). There are probably quite a few others out there, too.
Might be the difference between spending $70 on an unknown vs $110 for a very high quality aftermarket part?
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Thanks all. Both scooters have about 1800 miles on the odometer so doesn't seem like they'd be so worn. But like I said the ring grooves were out of tolerance, assuming I measured things correctly. And thanks for the suggested research, checked out several scooter parts sites and videos and think I'm just going to order a stock rebuild kit (new cylinder, rings, piston, etc.) and see if I can just get one running. If I can I'll tackle the other one and maybe "hop" it up a bit. I'll post updates in case anyone is interested. Cheers.
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Okay so finally go around to installing a new piston and rings. I now have spark, fuel, and compression. AND IT STILL WON'T START!!! >:(
I've drained the fuel tank and pulled out the carb. Ran carb cleaner through the whole thing and reinstalled it. Just have to get some fresh gas tomorrow to see if that works.
I also don't know where the final vacuum line to the fuel valve/filter goes. Here is a pic, the 4th nipple doesn't have a line on it and i can't for the life of me find where the line is supposed to attach to. I assume it goes to manifold vacuum somewhere but i can't find a a fitting to connect it to. Anyone know?
If this doesn't work these 2 scooters might end up in the Petaluma River! Any thoughts, ideas, or wild ass guesses are welcome.
Cheers.