GS Engine Knock

[freded]

I've got a engine knock at idle when the engine is hot, it sounds like it's coming from the left head but hard to determine where it is coming from. When engine is cold no knocking. 2002 adventure with 28K miles. any ideas?

[Jeff]

If you think the sound is comming from a cylinder head and not engine case it may be one of the rocker arm shafts may have too much end play. This can be adjusted for much the same way as on an airhead.

[Manhattan Rider]

Need a little more information. What octane gas are you using? What type of riding do you do?

It common for an oilhead to knock a bit at six bars if the motor has a carbon buildup. When I lived in Washington, D.C., my oilhead carboned up and knocked badly at six bars and beyond.

The fix was using a higher-octane gas and getting the bike on the road for an extended period. I heard Paul Glaves once say, "you have to keep oilheads spinning." Meaning, that motor needs to get out on occasions and run for extended periods of time at 4000 plus RPMs.

My wife and I just returned from a trip to Glacier National Park, riding about 3700 miles in 7 days. Good shares of these miles were at higher RPMs. I am now at 12K since I last service my RT and I do not know how it could run any better. I will do a serviced in a couple weeks, but my RT no longer knocks at any heat range.

[saab93driver]

I wouldn't think a knocking noise at idle would be low octane gas since there is little or no load on the engine.

Possible guess would be cam chain tensioner which is oil pressure sensitive. Also it might be the throttle butterfly hitting the stop on the left TB - sometimes at idle they flutter around and the stop screw hitting the stop makes a tapping sound.

[freded]

Low rpm is not the answer, my cruising rpm is generally between 5500 and redline along with using highest octane available. My rear drive also just went out at 28K miles. I also checked the end play on the rocker arms and they were ok, the tensions could be the problem. Since new in addition to the rear drive going out, the quick-disconnects on the gas tank have broken, spark plug wires burned up, cat eliminator pipe broken (remus) other than those items it has run perfect. It developed a vibration that felt like going over a wash-board road after a 500 mile blast at an average of 6000 rpm and redline and over 100 degree temperature, that was the rear drive. Should the GS not be ridden this hard? By the way the gas mileage sucks at that rate only about 200-220 miles to the tank.

[pbansen]

Is it a knock or more of a persistent tap? Does is continue when you raise RPMs above idle?

My '97 R1100GS has a tap that seems to come mostly from the left side (although it's kind of towards the center of the engine on the left side, if that makes any sense). It doesn't appear until the bike is at operating temperature and it seems to go away above an idle. This bike has about 24,000 miles.

The valves are adjusted perfectly per the Oilhead Valve Adjustment for Dummies (OVAD) procedure. I have adjusted the rocker arm end play so that it is within spec and minimal (like twice the minimum - there is a rather broad range). The noise persists.

Some well-informed folks have suggested that it is the throttle body shaft on the left side rattling a little bit, but it just doesn't have that sound to me.

I'm starting to think that maybe 'they all do that'... True?

Pete Bansen
Truckee, California

[freded]

Those are my exact symptoms. I took it to the dealer when I had the rear drive replaced and asked them to diagnose the tapping noise. They adjusted the valves, the end-play, the cam tensioners and still the tapping continues in fact the hotter it gets the worse it gets it sounds as if the engining is going to knock a rod at ide but disappears at about 2000 rpm. The dealer is going to ask the BMW service rep and am waiting on that answer. Will let you know what the service rep says. By the way Santa Fe BMW took a new rear drive off a 04 Adventurer so I could get back on the road.

[kbasa]

It sounds like the cam chain to me. Our RS makes some of that noise, especially when it's hot. After listening to it for 45K miles, I've learned to ignore it.

That said, I'd still get someone to listen to it. Also, try and listen to other bikes and see if yours sounds the same.

dave

[gsr]

My 1150 gs has similar knocking from the right side of the engine at idle when warm. Dealer kept bike for over four months. Engine found to be "in spec." After reasembly, knock was gone for 400 miles or so. Called the bmw rep and was basically sent back to the dealer. Don't waste time calling customer service. Anyone out there have any answers? No, it is not the throttlebodies or valve train noise. The noise is from farther to the rear of the engine and you can hear valve train noise at the same time which sounds different. This a knock with pounding you can feel in the bars and pegs. It sounds like the timing chain tensioners at start up. Stranger yet is the fact that when it is started cold and brought up to highway speeds say, 4,000 rpm in 6th gear, everything is smooth until you stop and let it idle. It doesn't matter if you ride 10 miles or 100 miles. After that when you stop and let it idle it knocks and vibrates upon returning to highway speeds. Any other R259 engines out there like mine?

[Manhattan Rider]

Stranger yet is the fact that when it is started cold and brought up to highway speeds say, 4,000 rpm in 6th gear, everything is smooth until you stop and let it idle

Hmm...it may simply be an overly lean condition. When your bike is cold, its running open-loop. So, its using a richer map that is running around 3% CO. However, when the bike is warm, the bike is running closed-loop. In closed-loop, the bike is running around 1.5% +/- .5%. Oddly enough, some oilheads running around 1.5% suffer lean-fuel surging while others operating at considerably less CO (1%) run leaner, however don't surge.

A good check is have your dealer run an exhaust gas analyzer at idle. Significantly less than 1.5%, and your bike is overly lean. If you had a 1100 series motor, I would recommend pulling the CAT Code Plug. That will default the motronic to a rich condition (4.5% CO) and if it fixes the problem, you know its a lean fuel issue. I would not recommend running at 4.5% CO. This will produce considerably more unburnt carbons then you want, potentially clogging the catalytic converter and/or build carbon in the combustion chamber..


However, on 1150 series motors, the bike will not default to a richer condition. You may want to try a Techlusion R259. You can adjust the CO to around 2.5%. This will only fix an overly lean condition....it won't fix a mechanical problem.

[kaseydoolin]

My 1200c has a intermittent knock. It sounds like a trash can full of wine bottles at cold start-up. When that goes away there is a tap-tap-tap at idle, especially after a good romp on the freeway. My very reliable dealer insists its a chain tensioner. I plan to have it replaced at the next service, we'll see?

[GlobalRider]

Originally posted by Ken Krumm
The fix was using a higher-octane gas and getting the bike on the road for an extended period. I heard Paul Glaves once say, "you have to keep oilheads spinning." Meaning, that motor needs to get out on occasions and run for extended periods of time at 4000 plus RPMs.

I realize that an engine under load will get hotter, but I don't understand why fuel infection doesn't keep the engine, no matter what rpm or state, at the ideal fuel/air mixture. Isn't that what fuel infection is supposed to do, expecially if it is a closed loop system?

[kbasa]

Originally posted by Global Rider
I realize that an engine under load will get hotter, but I don't understand why fuel infection doesn't keep the engine, no matter what rpm or state, at the ideal fuel/air mixture. Isn't that what fuel infection is supposed to do, expecially if it is a closed loop system?

I'll post a chart tomorrow that shows CO at different rpms on our RS. Below 4K, it's very, very lean. Would this lead to pinging?

[GlobalRider]

Originally posted by KBasa
I'll post a chart tomorrow that shows CO at different rpms on our RS. Below 4K, it's very, very lean. Would this lead to pinging?

Absolutely...depending on loading.

[saab93driver]

I understand pinging under load but at idle with no load I don't think it is likely. Possible? sure, anything is possible, but I would be inclinded to think the noise is more mechnical in nature.

[kbasa]

Here's a dyno plot, with 4 gas EGA results included.

It's broken into steps, with throttle position as a grouping and rpm as a sub under the throttle position.

There's one spot where the tester (Patrick Burns, :wave Pat!) noted PING. This was where the bike was really pinging loudly. Notice that he also indicated where the bike surged.

http://kbasa.smugmug.com/photos/1247420-L.jpg

There's also a full sized version here. (http://kbasa.smugmug.com/photos/1247420-O.jpg)

What do you guys think? See anything funny going on with the CO values?