Rebuilt front cylinder. Only 100 psi after rebuild - GT125R Engine Rebuild // Hyosung Forums Owners Club

Rebuilt front cylinder. Only 100 psi after rebuild – GT125R Engine Rebuild

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This topic has 5 replies, 2 voices, and was last updated 2 years ago by Simon.

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- Oct 19, 2024 at 8:41 PM #15243
  
  Brian
  Participant
  
  As the title states, i have rebuilt the front head, got a piston, new rings, gaskets etc. Checked compression, its at 100 psi. Is this normal? Do they need time to seat? Thank you in advance
- Oct 20, 2024 at 9:37 AM #15246
  
  Simon
  Participant
  
  Did you lap in the valves?
- Oct 20, 2024 at 10:01 AM #15247
  
  Brian
  Participant
  
  No i didnt lap thr valves
- Oct 20, 2024 at 5:46 PM #15249
  
  Simon
  Participant
  
  When rebuilding the cylinder the valves need to be done it’s the most common place for blow by, normally worn rings/bores show with oil burning
- Oct 21, 2024 at 5:29 AM #15253
  
  Brian
  Participant
  
  Amazingly the bike is running better than ever, psi is slowly going up on compression, had her running for ten minutes and its went up 10psi. I will need to lap the valves. Weather is aweful atm so will get them done when i can. Thank you for your help and support. Will i need a new head gasket again?
- Oct 21, 2024 at 6:11 AM #15254
  
  Simon
  Participant
  
  Yeah always fit a new head gasket & remember the valve shims/ clearance will need adjustment.
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FORUM ARCHIVE: Boards are now read-only as archives. For bike service manual downloads, parts shop, or to read more about the forum changes, tap here to read more....

This topic has 5 replies, 2 voices, and was last updated 2 years ago by Simon.

Viewing 5 reply threads

Author

Posts
- Oct 19, 2024 at 8:41 PM #15243
  
  Brian
  Participant
  
  As the title states, i have rebuilt the front head, got a piston, new rings, gaskets etc. Checked compression, its at 100 psi. Is this normal? Do they need time to seat? Thank you in advance
- Oct 20, 2024 at 9:37 AM #15246
  
  Simon
  Participant
  
  Did you lap in the valves?
- Oct 20, 2024 at 10:01 AM #15247
  
  Brian
  Participant
  
  No i didnt lap thr valves
- Oct 20, 2024 at 5:46 PM #15249
  
  Simon
  Participant
  
  When rebuilding the cylinder the valves need to be done it’s the most common place for blow by, normally worn rings/bores show with oil burning
- Oct 21, 2024 at 5:29 AM #15253
  
  Brian
  Participant
  
  Amazingly the bike is running better than ever, psi is slowly going up on compression, had her running for ten minutes and its went up 10psi. I will need to lap the valves. Weather is aweful atm so will get them done when i can. Thank you for your help and support. Will i need a new head gasket again?
- Oct 21, 2024 at 6:11 AM #15254
  
  Simon
  Participant
  
  Yeah always fit a new head gasket & remember the valve shims/ clearance will need adjustment.
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