BMW K bikes (Bricks)

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1Back to top Go down   Tight Valves Empty Tight Valves on Sat Jun 20, 2020 6:11 pm

zaubertuba

zaubertuba
Silver member
Silver member
Just checked my valve clearances.  One intake is a little tight and ALL the exhaust valves are tight--it seems very tight:

I1 .15
I2 .12
I3 .15
I4 .15

E1 .20
E2 .12
E3 .15
E4 .15


Bad enough to warrant reshimming?


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1985 K100RS
    

2Back to top Go down   Tight Valves Empty Re: Tight Valves on Sat Jun 20, 2020 6:13 pm

Laitch

Laitch
Life time member
Life time member
Yes. All valve clearances should be within spec.


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1995 K75 77,000 miles
Tight Valves Usa-lo10
    

3Back to top Go down   Tight Valves Empty Re: Tight Valves on Sat Jun 20, 2020 6:28 pm

moriarti

moriarti
Gold member
Gold member
Reshimming might help with MPG as well Very Happy


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1984 k100 rs red/black VIN  0004449
    

4Back to top Go down   Tight Valves Empty Re: Tight Valves on Sat Jun 20, 2020 7:04 pm

zaubertuba

zaubertuba
Silver member
Silver member
@moriarti wrote:Reshimming might help with MPG as well Very Happy

Heh it might. Wink 

So since they seem to get tighter is it fair to assume I should shim towards the looser side of the specs?


__________________________________________________
1985 K100RS
    

5Back to top Go down   Tight Valves Empty Re: Tight Valves on Sat Jun 20, 2020 7:11 pm

moriarti

moriarti
Gold member
Gold member
Correct,shims/tappets settings reduce with heat,so a little give is ok,hence the max/minimum numbers .Tight settings,valve not closing/seating fully,means,loss of power hence poor mpg



Last edited by moriarti on Sat Jun 20, 2020 7:18 pm; edited 1 time in total (Reason for editing : brain in slow mo)


__________________________________________________
1984 k100 rs red/black VIN  0004449
    

6Back to top Go down   Tight Valves Empty Re: Tight Valves on Sat Jun 20, 2020 8:01 pm

moriarti

moriarti
Gold member
Gold member
Also do a compression test first cold and one with oil added then again after valves done to give you a comparison Very Happy


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1984 k100 rs red/black VIN  0004449
    

7Back to top Go down   Tight Valves Empty Re: Tight Valves on Sun Jun 21, 2020 12:18 am

Point-Seven-five

Point-Seven-five
Life time member
Life time member
Tight exhaust clearances cause burnt valves because good contact to dissipate heat can't be made when the valves close.  The hotter exhaust valves also expand more than the cooler intake valves reducing the clearance more as the engine gets hot.  Shim them to the wide end of the spec. 

Intake valves, on the other hand, are cooled by the incoming fuel/air mix.  Tight valve clearances on intake valves help the engine breathe better.  It's no big deal if they are at the tight end of the spec.  Just make sure they are still in spec.

I try to get the clearances as close to the same as possible, it makes for a smoother idle.


__________________________________________________
Present:
1994 K75RT
1991 K100RS
1988 K100RS SE

Past:
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

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