valves adjustment

[carbold]

Done my valves adjustment the other day, I’d read so much about it that it went smooth and no probs at all (apart from finding the bloody TDC with a dodgy torch).

After that I balanced the TBs with twinmax, vibrations went down a lot especially at idle, the only thing is that the bike (R1150GS) feels a little bit lazy and slow if you know what I mean…

Did I do something wrong or am just being paranoid?

 

[Steptoe]

or am i just being paranoid?

you might be, not sure, what'd ya think, no harm in being paranoid though, cause you never know.

 

[ag1s]

Done my valves adjustment the other day, I’d read so much about it that it went smooth and no probs at all (apart from finding the bloody TDC with a dodgy torch).

After that I balanced the TBs with twinmax, vibrations went down a lot especially at idle, the only thing is that the bike (R1150GS) feels a little bit lazy and slow if you know what I mean…

Did I do something wrong or am just being paranoid?

carbold,

Unadjusted valve clearences (larger gaps) promote better low-mid range performance and worse top end and vice versa. Actually adjusting the valves to a twice as big a gap is a standard performance increase, bar the top end, for this bike. I hope this helps!

 

[carbold]

It does help!
You know when you use the feeler gauges and you move them into the gap, I deliberately chose a tight fit for all the valves, meaning that I felt good friction when sliding them up and down the gap...I just looked for the same "friction" when moving them in all the gaps.
Does this make sense?!
Paranoid again?

 

[(RIP) Kaister]

Unadjusted valve clearences (larger gaps) promote better low-mid range performance and worse top end and vice versa. Actually adjusting the valves to a twice as big a gap is a standard performance increase, bar the top end, for this bike.

I can't see why 'worse top end or a 'std performance increase' ?

smaller gaps means more valve open area and sooner, also means more valve overlap and more exhaust 'extraction' , also helps with pulling in the inlet mixture. ( all completely theoretical when talking about a couple of thou )

Also, valve clearances usually tighten these days, not get bigger, due to larger surface area of the valve operating mechanism.
The days of the bonnevilles are gone.
The valves actually 'sink' into the head from valve head and seat wear, thus closing the gap.

All engines are slightly different and each valve behaves differently within each engine - otherwise they'd all be wearing at the same rate.

 

[Spout]

Don't know if it's true of the oilheads (I've not looked into it yet) but the old airheads cylinders used to 'stretch' and play havoc with the valve clearances.
Re torque the cylinders THEN set the tappets.

 

[agis]

I can't see why 'worse top end or a 'std performance increase' ?

smaller gaps means more valve open area and sooner, also means more valve overlap and more exhaust 'extraction' , also helps with pulling in the inlet mixture. ( all completely theoretical when talking about a couple of thou )

Also, valve clearances usually tighten these days, not get bigger, due to larger surface area of the valve operating mechanism.
The days of the bonnevilles are gone.
The valves actually 'sink' into the head from valve head and seat wear, thus closing the gap.

All engines are slightly different and each valve behaves differently within each engine - otherwise they'd all be wearing at the same rate.

Motomartin,

More open valve area is not always desirable. This is why multivalve engines perform better at high revs (see new honda vfr vtec).
Anyway, somebody has already tried it and here is what he has to say. I'm sure he knows better:

Valve Lash Increase - Rob Lentini
If you are like me, try this. I like low and mid-range driveability and throttle
response. My R1100RS would not idle for several minutes on cold mornings
until I increased valve lash. Increasing valve lash FIXED the problem, and I've
lost no discernible top-end power. Increased valve lash is equivalent to closing
the valves sooner--"milding" the cam timing.
Set the valves COLD from/to:
Intake: Spec: .006" to: .012"
Exhaust: Spec: .012" to: .014"
Your idle will be MUCH smoother and throttle response immediate but
controllable. Increase in valve noise is minimal. Valves will run cooler.
Results of Increased Valve Lash and Advanced Timing - Rob
Lentini
The following results were obtained from several runs on a dyno with my 1994
R1100RS:
1. Advanced timing (9 degrees) results in a 2 - 4 horsepower increase across
the entire RPM range. The 4 horsepower increase was in the meat of the power
band, from 6000 RPM and up. There was no detonation.
2. The average torque and horsepower, across the entire 4th gear roll-on range,
3500 - 7500 RPM, was improved by increased valve lash.
2. Increased valve lash and advanced timing (9 degrees) netted an average
torque increase of 3.1 and an average horsepower increase of 4 over
stock valve lash and stock timing (6 degrees).


agis

 

[Steptoe]

you can get the same type of miniscule increase of driveability by lightning the bike/rider. Have a dump before you go out, lot less bother.

 

[carbold]

 

[The Mechanic]

The right 'feel'..if you get my drift!

To make sure you always get the same 'feel' between each valve, or for any other form of measurement using feeler gauges say for example spark plug gaps try this 'feel' technique:

With clean finger and thumb place a feeler blade between both and just let your finger and thumb rest on the blade, now slide the blade back and forth. This action should produce exactly the type of gap 'feel' that is needed for accurate settings.

It is very easy to overtighten valve clearances and still assume that just because the feeler blade moves that the gap is correct.

The most accurate method is to use a DTI (dial test indicator) but for such an agricultural engine good old feeler blades should do; unless of course you really are after that last final quarter H.P.