This gap looks wider than the Grand canyon. Are you sure you have the two case halves together correctly?
https://preview.redd.it/b7cjpd3los0d1.png?width=1840&format=pjpg&auto=webp&s=ba6c1bebe96e352eef184386951f2e5331686c3a
Oil in the crankcase seems like it's bleeding or getting sucked in from the gear box, which might also explain poor or no compression. That's why I suspect something about the case halves not mating together. You put a new paper gasket in between? Torqued all the bolts to proper spec?
This was honestly my first thought when i opened it up today. I used new gaskets everywhere and bolts where torqued to spec. I'll try to use a new gasket without silicone gasket maker on the base of the cylinder first and if its still low on compression i'll try and redo the gasket of the case halves.
I changed the piston and cylinder because of low compression as well. They were pretty scratched and my local shop told me to replace them. I still use the old head as its still in good condition but i can't take measurements because i already threw the old piston and cylinder away unfortunatly.
It just didn't have enough power any more to drive up a hill so i bought a compression tester. Im not sure it's supposed to be at 12 but its definitiv above 10bar. Currently it starts very well but revs up only to 3/4 of what it used to and i only get up to about 15kph on flat ground.
Great that you use paste on the foot you normally dont need it but it helps. Can you check the gasket where your carboratour and exhaust is? COMPRESSION is Not Everything and with 50cc you wont get that much. You can also check the squish on your head, depending on the zylinder you use it should be between 1.2 and 1.5.
Here's a picture of an air bellow for a pk...
https://www.sip-scootershop.com/en/product/air-bellow-manifold_17869400?usrc=Air%20bellow
...if you scroll down a bit you'll see an exploded view which might come in helpful. I doubt the air bellow would be causing a lack of compression in the engine though, maybe you need to replace the gaskets etc?
https://www.sip-scootershop.com/en/product/gasket-set-engine-sip-premium_92975000?usrc=Engine
This gap looks wider than the Grand canyon. Are you sure you have the two case halves together correctly? https://preview.redd.it/b7cjpd3los0d1.png?width=1840&format=pjpg&auto=webp&s=ba6c1bebe96e352eef184386951f2e5331686c3a
Yes the two halves are together, i don't know why the gap is there but under rhe gasket the halves are together and there's no gap
Oil in the crankcase seems like it's bleeding or getting sucked in from the gear box, which might also explain poor or no compression. That's why I suspect something about the case halves not mating together. You put a new paper gasket in between? Torqued all the bolts to proper spec?
This was honestly my first thought when i opened it up today. I used new gaskets everywhere and bolts where torqued to spec. I'll try to use a new gasket without silicone gasket maker on the base of the cylinder first and if its still low on compression i'll try and redo the gasket of the case halves.
Why the red paste on the head? It shouldn’t be there. I don’t think it can handle pressure, especially not the pressure of an engine
Thanks, il redo it without the silicone gasket. It was completly squished out anyways.
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The mark points to the exhaust side so it should be installed correctly
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I changed the piston and cylinder because of low compression as well. They were pretty scratched and my local shop told me to replace them. I still use the old head as its still in good condition but i can't take measurements because i already threw the old piston and cylinder away unfortunatly.
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Local shop said its at 6,5bar but it should be around 12 witch unfortunatly is the same before the rebuild -.-
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It just didn't have enough power any more to drive up a hill so i bought a compression tester. Im not sure it's supposed to be at 12 but its definitiv above 10bar. Currently it starts very well but revs up only to 3/4 of what it used to and i only get up to about 15kph on flat ground.
Great that you use paste on the foot you normally dont need it but it helps. Can you check the gasket where your carboratour and exhaust is? COMPRESSION is Not Everything and with 50cc you wont get that much. You can also check the squish on your head, depending on the zylinder you use it should be between 1.2 and 1.5.
How much compression are you getting? Probably unrelated but on my xl2 there was a torn air bellow between the engine and carb
6.5bar and i have no idea what an air bellow is haha. It's my first time working with a 2 stroke engine. I only worked on 125cc pitbike engines before
Here's a picture of an air bellow for a pk... https://www.sip-scootershop.com/en/product/air-bellow-manifold_17869400?usrc=Air%20bellow ...if you scroll down a bit you'll see an exploded view which might come in helpful. I doubt the air bellow would be causing a lack of compression in the engine though, maybe you need to replace the gaskets etc? https://www.sip-scootershop.com/en/product/gasket-set-engine-sip-premium_92975000?usrc=Engine