Seeking Advice

awshucks · Dec 17, 2009

Bought an '81 R100 w/ 40k on the clock. Runs great, but has picked up this nasty habit of smoking profusely out of left pipe on cold start. I've eliminated side stand puffs, bad pcv set up, ect. Bike runs and idles fine.

Compression is around 115 both sides, doubt it is a valve problem. Had resigned myself to a faulty valve guide, until I was told tonight it may be valve guide seals. Don't even know if they exist? I do know I love this bike and will write checks to keep riding it.

Since that appears to be a cheap easy test, am inclined to go w/ it.,

I know nothing about wrenching or mechanics, be gentle, lol.

Your thoughts?

barryg · Dec 17, 2009

Do you know for sure if the 40,000 miles is correct.

81twins · Dec 17, 2009

Do you leave it parked using the side stand? Some of the older airheads will occasionally smoke from the left cylinder if left parked for longer periods of time on the side stand. How have you eliminated this as a problem..?

keelerb · Dec 17, 2009

115 is a little low (if you did the compression test correctly, with engine warm, WOT, plugs out, preferably carbs off) but not crazy low, and it's great that the readings are consistent.

Leakdown test would be the best advice at this point - pinpoint any issues.

Failing that, try a dry/wet compression test - repeat your test, and then put a tablespoon of oil through the plug hole in the cylinder you're testing. If compression goes up significantly, that usually means bad rings. Significantly is the operative word here. And ideally, you would confirm the diagnosis with a leakdown test before spending the time and money to replace rings.

Good luck, and do let us know how you make out.

26667 · Dec 17, 2009

rings?...sumpin' leakin' if it's 115

jforgo · Dec 18, 2009

There are no valve guide seals

ccolwell · Dec 18, 2009

81twins said:
Do you leave it parked using the side stand? Some of the older airheads will occasionally smoke from the left cylinder if left parked for longer periods of time on the side stand. How have you eliminated this as a problem..?

A lot of them do this.

TGHSMITH · Dec 18, 2009

a 81 to 84 most likely will need new ex. seats and valves some time, do the through the sparkplug hole look at the valve edge, followed by a leak-down test. if the edges look bad forget about the leak-down and just pull the heads.. the deformed valves can give good leakdown results. the valve guides going bad can make smoke also...

awshucks · Dec 18, 2009

81twins said:
Do you leave it parked using the side stand? Some of the older airheads will occasionally smoke from the left cylinder if left parked for longer periods of time on the side stand. How have you eliminated this as a problem..?

Put a 130 mile ride on it w/ no side stand, we're talkin mosquito fogger type smoke for 15-20 seconds on firing up.

awshucks · Dec 18, 2009

jforgo said:
There are no valve guide seals

Sounded too cheap when I heard it, lol.

awshucks · Dec 18, 2009

barryg said:
Do you know for sure if the 40,000 miles is correct.

I found the bike on consignment w/ a dealer, he's familiar w/ the two PO and claims the mileage is correct. This is a recent affliction, wasn't doing it when I bought it, I've put about 1800 miles on it since late August.

SCJACK · Dec 18, 2009

It wouldn't be that unusual to see a 1981-1984 with 40k miles that needs a valve job. It would be a good idea to replace the rings while it was apart. I presently have a 1981 R100RT and it needed a valve job at 45k miles. I've owned other 1000 cc models that fell into this same category.

Also, the compression is too low. Valves and rings will solve the problem and if maintained properly will probably last for another 100k+ miles.

Yarddog · Dec 18, 2009

I've seen a lotta comments on this site that have led me to the opinion that this is a normal thing when parked on the side stand...mine does if from time to time, not all the time, and I have learned to not get my panties in a wad about it... If all else is well, just blame it on that vaunted Teutonic engineering...LOL

dennisdarrow · Dec 18, 2009

Is this a one time thing or does it constantly? Using oil? At those few miles, if it was at all maintained it should not need valves........Just my thoughts but before tearing into it would check the valve clearances every 500 to 1000 miles to see if stuff is changing. Seems to me that folks just want to tear into these things just to tear into them. History though says they go a very LONG way before actually needing a top end overhaul.

Does it do it all the time or was it just a one time shot. Both cylinders measured the same, so even though low, yes, something tells me that the test was just a bit faulty?

Anyway......Good luck......Dennis

awshucks · Dec 18, 2009

The comp test was good, heated the engine up some as directed and pulled the carbs. Did it a couple times on each side.

I had three of these in the past and am familiar w/ side stand start up puffs. This is constant every day, only on cold engine.

The bike has gone through almost a quart in under 2K. It doesn't seem to smoke when running or warmed up, know PO used BMW oil 20w-50. Seems like I recall the 'K' bikes smoking and BMW came out w/ an oil that didn't smoke when burning [as legend and a poor memory have it]. Am curious if I have that oil and am steadily burning it and don't see it.

Everyone is a champion in their own backyard, mine just ain't automotives, and I appreciate all your insight.

My plans are to send the heads off to Memphis Motorwerks and get the valves looked at, new guides installed, what ever it takes. I'll put rings in while it's torn down and be done w/ it.

I'm in Bumm F Egypt part of Ar [can't get anything here]and have plans of some real road trips this spring, Illinois and Florida.

I got an Ed Korn exhaust nut wrench and am waiting on UPS to bring my Kroil. I've lived here since '02 and go for a 5 mile ride every Xmas up on top of the mountain to a State Park, and just grin. Something I couldn't often do in Illinois.

I have a good friend that's an aircraft mechanic who rides, he wrenches for next to nothing.

I'll post some pics when I get it torn down. Again, thanks for your help.

20774 · Dec 18, 2009

I've not heard that BMW came out with some oil to cure a smoking K-bike problem. BMW's dino oil is good stuff...should be rebadged Spectro. It's usually the cheaper oils that will "burn off" the additive package quicker. Spectro and BMW oils should be fairly stable.

Not sure where Bumm F Egypt AR is...isn't there a dealer in Bentonville and in Little Rock? I don't know anything about their friendliness towards Airheads, though...

PHMARVIN · Dec 18, 2009

Hi, Awshucks,
You have an '81 R100. The '81-'84 bikes (all the boxers) had bad valve SEATS from the factory. The seat material did not transfer enough heat, thus the valves would deform. The problem is more pronounced with the 1000cc bikes. Be prepared to $pend con$iderable money for reworked heads. I would expect valve seats, exhaust valves, maybe intake valves and valve guides. I've heard good things about Memphis Motorwerks on this list, but if they do not mention valve seats (and the seats have not already been changed), I would run, not walk, there and retrieve my heads posthaste and send them to Oak, Tom Cutter, Anton Largiader or Ted Porter and have them done correctly. With your oil usage, I would probably also change the rings. Good Luck!

keelerb · Dec 18, 2009

Okay. Several folks have mentioned the valve guides. At least one guy says there are none.

Can we get a consensus here? Does the bloody bike have guides or no? :ear

bikerfish1100 · Dec 18, 2009

the statement (by jforgo) was that the motor does not have valve guide seals, not that it does not have valve guides.
the valve stem needs to "ride" in something, and you want that something to be replaceable when it wears out- that something would be a valve guide.

awshucks · Dec 19, 2009

PHMarvin said:
Hi, Awshucks,
You have an '81 R100. The '81-'84 bikes (all the boxers) had bad valve SEATS from the factory. The seat material did not transfer enough heat, thus the valves would deform. The problem is more pronounced with the 1000cc bikes. Be prepared to $pend con$iderable money for reworked heads. I would expect valve seats, exhaust valves, maybe intake valves and valve guides. I've heard good things about Memphis Motorwerks on this list, but if they do not mention valve seats (and the seats have not already been changed), I would run, not walk, there and retrieve my heads posthaste and send them to Oak, Tom Cutter, Anton Largiader or Ted Porter and have them done correctly. With your oil usage, I would probably also change the rings. Good Luck!

Thanks! There's a package of missing paperwork on the bike, supposedly there's been some head/valve work done by original owner, I'm the third.

The heads are still on the bike, hopefully, I'll learn more once I get them off and post some pics for you guys to advise on.

I'm not a lucky type guy, had 3 'S' models in the past, and wanted another, this was as close as I could come weighing all the factors, time, distance, and money. I've already dumped a pile of the latter on fairing, mounting, gauges and paint.

Truth be told, I joined BMWOA to get at the bikes for sale ads, not realizing all the other benefits that came w/, not the least of which is this valuable advice. Since then, I got to meet a gentleman in my area that's in 'Anonymous', attend a local rally 5 miles from me, while there help another airhead owner w/ road repair problem by making the slug needed to pull a rotor.

I also 'met' the PO of my bike on another forum, and he's graciously provided me w/ into too.

Seeking Advice

awshucks

Guest

Active member

New member

keelerb

Guest

the Wizard of Oz

New member

Member

TGHSMITH

Guest

awshucks

Guest

awshucks

Guest

awshucks

Guest

Life Member

Yarddog

Guest

#4869 Earned Lifetime mem

awshucks

Guest

Liaison

New member

keelerb

Guest

New member

awshucks

Guest

Similar threads