Leaking valve seals?

[LCP92]

Guys, I've got a 1999 Honda Foreman 450S.  It runs great, but smokes out the exhaust after startup until it warms up.  I'm thinking the valve seals are leaking.  I was wondering if there is a way to replace them without removing the head or if there's an oil additive that will recondition the rubber seals.  Any advice?

[av8092]

Two ways

Get an air hold fitting to add air through the spark plug, or bring near TDC and put cord through the plug hole until full, rotate to compress the cord which will hold the valves from falling into the cylinder.  Remove springs and seals install new