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Engine Idle


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I'm getting ready to take the plunge $$$$ for a set of Ohlins at 62,000 miles. But before I invest $$$$ I've got a question concerning the engine.

Even after a good tune up, TBS, Valves, plugs (the works); my engine idles okay.....(1100rpm) but it seems to "miss a beat" or 'Hickup'; during idle. It's not purring smooth like a K Bike.

Is this normal for some boxers? Could it be an indication of worn throttle bodies? Or something else.

I hesitate to spend the money on Ohlins if there is something else lurking $$$$ wise.

Bike runs great on the road! But even as I TBS at 2500 RPM it misses a beat now and then. That's what bugs me. AND it's th'e only thing that bugs me about my RT smirk.gif

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It's more or less normal. Not perfect but, you can expect it and learn to live with it. You can improve the situation somewhat by setting your TPS voltage closer to 380 mV at idle as that will slightly richen the mixture, assuming your stock voltage is less. Every one I have ever checked has been lower. That "miss a beat" feeling is actually lean stumble so richening the idle mix will help.

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I'm relatively new here, but also had a rough idling RT (1150). While idling, it would have a variation of about 150 RPM. A tune up helped, but upgrading the left cam chain tensioner greatly improved the idle quality. It still stumbles as Ed describes as a common quirk, but now the RPM needle isn't bouncing all over the place. If your RPM isn't changing significantly, this probably isn't what you describe, (and may not be anyway).

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Ed, what you said....makes sense, The 'stumbling' does not seem to occur when the engine is cold all the way up to about 2-3 bars(richer mixture?)

Thanks! can't wait for those Ohlins thumbsup.gif

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Mine does it. It even feels like it's about to stall once in a while at stop lights. The bike runs great at every other part of the power band - no surging or any of the other common complaints.


Maybe "they all do that", but I'm still not satisfied. I know I already have problems with the fuel regulator (crushed fuel line), and I've got the cam chain tensioner upgrade on my "to do" list also. My gut feeling is that with this bike (2001/55K miles) at this age, it could quite easily be a vacume leak problem somewhere in the intake. The "zero-zero" TPS sync might help with the problem too.


I know the Beemers aren't Honda's, but it still seems to me that a bike should idle without missing or stalling, so I'm going to work on this thing until I figure it out. (All I need is two weeks to work on it. Just two weeks, maybe 14 days... that's all. I'll start next month.. probably grin.gif. 'Til then I'm just "talk".)

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Kind of depends how much "stumble" we are talking about. A bit of an irregular idle, call it a 'lumpy' idle is TADT. Sort of like a missed beat.


OTOH a dramatic drop in RPM (500 RPM drop or more) such that the bike almost (or does) stall is not normal and indicative of some other issue. TPS voltage being a suspect.

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Al Navecky Jr

All of the twins (boxer, V, and parallel) I have do this to some extent. The K bike with more power pulses will idle smoother the a twin.

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My RT's idle used to stumble some whether cold or hot. It was kind of annoying at stoplights. Autolite plugs helped, especially in the cold. Then I got a Techlusion R259 and -- miracle of miracles -- the bike idles perfectly on dead-coldddd startup as well as at full operating temp. No stumble, just a sweet steady ch-ch-ch-ch-ch at 1000 rpm. The only drawback is that I'm now barely getting 40 mpg around town this winter, but the zero-surge drivability benefits are well worth it.


BTW, there's going to be cold rain here this weekend, so I'll be holed up in my garage -- my new Ohlins are finally going to get out of their box and onto my bike. I may try to take some pics of the install.

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