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

[Brian]

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

[Simon]

Did you lap in the valves?

[Brian]

No i didnt lap thr valves

[Simon]

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

[Brian]

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?

[Simon]

Yeah always fit a new head gasket & remember the valve shims/ clearance will need adjustment.

[Author]

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