Husqvarna SM 610 2006 Workshop Manual page 79

E N G IN E O V E R H A U L IN G
C ylin d e r h ea d
R e m o ve ca rbo n de po sits from the com bustio n cham b e r u sin g a ro u n d e d
scra pe r.
D o n o t u se a s h a rp to o l to a vo id valve se a ts a n d s p a rk p lu g th rea d
d a m a g in g .
C h eck the m a chin e d su rface s of the c ylind er h ead u sin g a stra ig h t e d g e a nd a
fee ler g au g e takin g rea dings at th e p oin ts show n in th e fig u re . If th e re ad ing a t
an y p oint is g rea te r th an the lim it pre scrib ed th en re g rin d th e co n ta ct surface
w ith th e c ylind e r.
C ylin de r h e a d d istortion lim it: 0 .00 19 in .
V alve s ea t
T his sh ou ld p ocke te d o r rece ssed and there sh o u ld b e n o tra ce s o f cracks o r
pitting . T o che ck if th e seat is dam ag ed proce ed a s fo llo w s:
- C over th e va lve se at w ith a u nifo rm la yer of re d le a d p a ste .
- F it th e valve in to its seat an d rotate a fe w tim es so th a t it le a ve s a n im p ressio n
in th e p aste . D u rin g th is opera tion h old the valve ste m stra ig h t w ith a ch uck
vice.
- T h e im p ressio n left in the p aste o n the valve seat sh o u ld b e co n tin u o u s w ith o u t
bre aks a nd the w id th o f the im pres sion (W ), w h ich co rre sp o n d s to th e th ickn ess
of th e se a t sh ou ld b e w ithin th e fo llow ing lim its:
- W = 0 .06 2 ÷0 .0 7 0 in . (n e w en gine: 0.03 9÷0.04 7 in.).
If the thickn e ss is n o t w ithin the se lim its the n re -cut th e se a t.
P roce ed a s fo llow s:
In se rt the g uide p in of th e m iller a nd rotate a fe w tim e s to re m o ve a n y d irt from the
sea t.
U sing the sam e p roce d u re as ab ove che ck the valve se a t. If it is da m a ge d or b urn
it w ill re qu ire fu rthe r m illing.
IM P O R T A N T : re m o ve a s little m aterial as p o s s ib le ; th is is to p re ve n t th e
va lve s te m fro m b ein g to o clo s e to th e ro c k e r a rm a n d th u s a lte rin g th e
co n tac t a n g le o f th e valve .
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S : E X H A U S T
A : IN T A K E