compression loss when installing right side crankcase?

Paulhenry · 02-05-2017, 12:44 AM

Hi guys. I'm wondering if anyone knows why when I tighten the right side crankcase up, I have no compression, but when I loosen the bolts off, the compression comes back.

I had to replace the old crankcase because it was cracked, so I took the crankcase off another motor I have. Both are Lifan 125cc 's and look identical. Both are second hand too.

I've got no idea what I am doing wrong. Thanks in advance, Paul.

Paulhenry · 02-05-2017, 03:17 PM

I forgot to say that the engine started when I had the crankcase off. I immediately shut it down then put the crankcase back on. It has compression right up until I tighten the bolts up.

This makes me think that it has something to do with the case squashing and causing the clutch to engage. Someone on another forum suggested loosening off the clutch adjuster the crankcase cover, bolting back together, then adjust the clutch to suit.

Does that sound about right? It sounds like it should work.

02-05-2017, 12:44 AM	#1
Paulhenry Join Date: Feb 2017 Location: Newcastle Australia Posts: 7	compression loss when installing right side crankcase? Hi guys. I'm wondering if anyone knows why when I tighten the right side crankcase up, I have no compression, but when I loosen the bolts off, the compression comes back. I had to replace the old crankcase because it was cracked, so I took the crankcase off another motor I have. Both are Lifan 125cc 's and look identical. Both are second hand too. I've got no idea what I am doing wrong. Thanks in advance, Paul.
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02-05-2017, 03:17 PM	#2
Paulhenry Join Date: Feb 2017 Location: Newcastle Australia Posts: 7	I forgot to say that the engine started when I had the crankcase off. I immediately shut it down then put the crankcase back on. It has compression right up until I tighten the bolts up. This makes me think that it has something to do with the case squashing and causing the clutch to engage. Someone on another forum suggested loosening off the clutch adjuster the crankcase cover, bolting back together, then adjust the clutch to suit. Does that sound about right? It sounds like it should work.
	0