Valve Adjust - Improving Performance, et al

[TaosBrick]

I've pored thru all the posts relating to maintenance, repairs and modifications, and nowhere do I see valve adjustment mentioned. Do K's have hydraulic lifters, or otherwise need no adjustment? Just wondering... if periodic adjustment is required, what are the specs?

Also wondering if little tweeks one might perform on other engines such as reducing valve clearance, advancing timing and so forth can be applied to K's to nudge performance. My guess is that "ze fyne Cherman engineerink" would probably not take too kindly to such crude monkeying, but maybe it would? I dunno, still very new to K-ness.

Lastly, what tweeks and aftermarket mods actually DO work to get a little more zip and top end out of a K? Mine is a '92 K75.

There really should be a section in this forum called "Ask Dr. Duck". Seems he's the one that weighs in with much of the useful info to be found here. Thanks, all!

[frankenduck]

K75 and 2V K100 valves are adjusted via shims placed between the valve "buckets" and intake/exhaust cams.  You need a special tool to depress the valve in order to remove the old shim and replace it with a thicker/thinner one.

Clearance specs(cold engine):

Intake: 0.15…0.20mm (0.0059…0.0079in)
Exhaust: 0.25…0.30mm (0.0098…0.0118in)

They're relatively static though do don't need to be checked very often once it's done initially after break-in.

Performance-wise there isn't a whole lot you can do to a K75/K100. (Short of turbocharging it.) Some people claim a little more pep by advancing the timing by 3 degrees but I've never bothered messing with that.

[TaosBrick]

Thanx, Dr. D - Will have to examine the meticulously kept records that came with the machine to see if re-shimming the valves had been performed as part of the break-in process.

As to the timing, the altitude loop on the fuel injection computer doesn't advance the timing too, does it? If not, perhaps a coupla degrees of advancement for my 7,000+' of altitude could be advantageous.

  I have read of this turbo-charging of which you speak. Luftmiester is the brand that comes to mind. How spendy-easy to install is it? And.. would it really be worth it for my otherwise docile ol' K75.

[frankenduck]

To my knowledge the altitude plug just adjusts the mixture, not the timing.

Can't hurt (and is free) to play with the timing a little.

I wouldn't bother trying to turbo a 20 year old engine.  If I wanted more power I'd just buy a newer bike. (or a K1100 of course )

[Rick G]

Anything up to 4 deg advance will improve the bottom end torque so that it is less prone to stall at take off and at very slow speeds in low gears it is far more rideable. However a timing advance will do zip for the top end performance because the rev limiter is what prevents it going any faster.
As for turbo charging to quote a friend of mine when I was Drag Racing "If you take an engine of at all doubtfull condition and blow the fuel and air onto the top it will most likely blow the guts of the engine out the bottom". A turbo charged engine needs to be specialy built and I am not just talking race engines.

[DRxBMW]

I've pored thru all the posts relating to maintenance, repairs and modifications, and nowhere do I see valve adjustment mentioned. Do K's have hydraulic lifters, or otherwise need no adjustment? Just wondering... if periodic adjustment is required, what are the specs?

* for the record, I have ONLY done one "actual shim replacement" over the lifetime of my K 75  (180 K + miles)  22K  #1 was just out of spec for tightness.

*  I check the clearances every 30K but they rarely move unlike my neighbor's Desmo.

* 3 degree timing advance does give the engine a bit more pep but in reality terms NOT worth the hassle unless you like to tinker.

* turbo is the same deal, HUGE waste of time & money for little gain at the end of the day. 

* the plug is beneficial at altitude. be me, I would wire up an on/off switch.  OTOH, most bricKheads don't even know where the hell the plug is located, so it's NOT that BIG of deal either way unless you live in the clouds.

* synching the throttle bodies to perfection does wonders for an older K

* R&R of tired ignition leads and new spark plugs is another

* air filters last almost forever but if the bike has high mileage, spring for a new one.

* ditto for the fuel filter, modern day petrol is chit,enough said, yearly R&R in my maintenance schedule.

* last but least, K bikes that are babied run better if you wring the piss out of them. Ha, above 5K,it's a "brave new world" power-band speaking, GO for it ! Riders that chug a lug are missing out,plus your machine will thank you.

[TaosBrick]

* last but least, K bikes that are babied run better if you wring the piss out of them. Ha, above 5K,it's a "brave new world" power-band speaking, GO for it ! Riders that chug a lug are missing out,plus your machine will thank you.

Believe me I do that on a REGULAR basis. :biggrin: Otherwise I'd not be asking about how to get more out of her, que no?

Anyhey, DRx - all points well taken. Will look into it all, particularly the throttle body synch. I'm bettin' that's never been done to ol' Chile Red in her entire lifetime of 30k.