K75 ignition timing

[F14CRAZY]

Is it necessary or advisable to check the ignition timing of a K75? Checking the timing as in hooking up a timing light and checking the spark advance as you would with an engine with a distributor. I've found some threads on people adding a little more advance but didn't really see anything about it being a regular maintenance item. I haven't read about it in any tune up threads.

[Chaos]

I've never checked or adjusted mine in 180,000 miles.  Advancing the timing may give incremental improvements but I never bothered to play with it. 

[The Mighty Gryphon]

Since some time in the mid 1980's it has been a government regulation that motor vehicles sold for use in the U.S. be designed to meet required emission and fuel economy standards without the need for "owner intervention" (tune ups) for the expected service life of the vehicle which was defined as at least 100,000 miles.  This included fuel/air ratios, ignition timing, spark plugs, and the exhaust system as far back as the catalytic converter.

As far as ignition timing, with electronic ignition, there is no need for tuning as there is no wear in the normal operation of the system as there was with the old breaker points which gradually retarded the timing as the cam rubbing block wore down. 

[F14CRAZY]

Thanks for the replies. It sounds like something one doesn't have to mess with unless they really want to

Since some time in the mid 1980's it has been a government regulation that motor vehicles sold for use in the U.S. be designed to meet required emission and fuel economy standards without the need for "owner intervention" (tune ups) for the expected service life of the vehicle which was defined as at least 100,000 miles.  This included fuel/air ratios, ignition timing, spark plugs, and the exhaust system as far back as the catalytic converter.

that'd be nice...my '07 Subaru Forester manual calls for spark plugs every 30k miles with normal driving.

[rbm]

Timing is checked statically, using a special adapter on a dial indicator. You have an electronic test instrument on the HES that indicates when it triggers, and you read the dial indicator to see how close the piston #3 is to spec.  No timing light involved because no timing marks available.

[The Mighty Gryphon]

They can call for maintenance within the 100,000 mile period, but if you don't do the service it shouldn't affect the emissions or reduce fuel economy below the published numbers.  There may be starting or driveability issues with old plugs in your Suburu, but the emissions and gas mileage won't be affected.  That would be illegal.

I just changed the 20 year old sparkplugs that have been in a 1995 Pontiac Grand Am since new and have 110,000 miles on them.  The gaps had opened up a bit, but the car still started easily, ran well, and never had a reduction in gas mileage from when I got it at 9,000 miles.  I haven't changed plugs in any car I owned in under 100,000 miles since the early 1990's.  I have left them in some for as long as 175,000 miles, specifically 1996 and 2000 Honda Accords.  The 2000 is still running and is closing in on 500,000 miles.

[F14CRAZY]

Well I came across this procedure:

http://skylands.ibmwr.org/tom/tech/k75_timing.html

[rbm]

Hmm.  Official BMW workshop manual shows a static timing process on pages 12-11.0 through 12-14.0, involving BMW ignition timer (BMW 12 3 650) and dial gauge extension (BMW 00 2 580). 

In that web page, he also writes "I wanted to apply my experience to my K75S, but was discouraged by lack of timing marks".  I've tries a method where I re-positioned the HES timing plate by trial and error, listening for pinging under load then backing off.

[F14CRAZY]

It's interesting but it seems I'm not really harming or neglecting anything by not messing with it.

At any rate, Drake probably would have if it needed to be

[skidmore]

Just yesterday I was browsing for OEM compatible air filters for my 75. I landed on ibmwr.org where some dyno results were posted. The test culprit was a K100 FWIW. Along with air filter dyno results were some ignition timing results. Maybe some of you that haven't seen them will find them interesting http://www.ibmwr.org/ktech/dyno/index.shtml

[F14CRAZY]

Hmmm. Well according to the dyno sheets it appears that 3-4 hp could be gained by bumping the timing though that's on premium (94 octane).

[The Mighty Gryphon]

Ok, so you advance the timing 10 degrees for 3-4 hp.  What happens when you are out and can't find anything but moonshine 87? 

I'll pass.