Hesitation at 4,000 revs?

[Sullivj]

i have a 2012, with just 7,000 miles in total.


This 'problem' has existed since I purchased the bike last year.  I mentioned it to my BMW dealer at the last service, but they said it was fine.  In reality, I do t think they tried hard to replicate the fault.


Mostly noticeable on the motorway, the bike hesitates ever so slightly around 4,000 rpm. In simplistic terms, it feels like someone is momentarily pinching the fuel supply.  If you open the throttle more, the hesitation disappears, and the bike pulls like a train.


Irrespective of the gear, it's always around 4,000 revs. Annoyingly on the motorway 70mph arrives about 4,000 revs, so it becomes more noticeable.


Anyone know what might be causing this?

[guest2360]

I would look carefully at its service history.  With only 7K it might just have had 5 or 6 annual services and never a full service which it gets at 12k.  It might still have the original,plugs in it.  Can't think of any other reason.  Did you get it from a main dealer, they will have access to its full history if it's been done within the network.

[Levisp]

Pre LC bikes require throttle bodies to be synchronised. When is that done ? At 12k with plugs ?

[Sullivj]

Thanks guys.


I got it from The Superbike Factory (who I would NEVER buy from again!). I contacted the supplying BMW dealer and obtained copies of all service invoices.


Looking at those invoices confirms that the plugs are the original ones, so maybe that would be a good place to start.


I had the synchronisation done at BMW last year.  That didn't cure it.

[David.]

I had the synchronisation done at BMW last year.

The engine synchronisation is due every 6,000 miles, as are the valve clearances.

The spark plugs are due every 12,000 miles, as is the air filter.
From experience, the air filter needs changing more frequently and after 5 years I'd put a new one in.

Air filter replacement, https://1200rt.com/viewtopic.php?p=10991#p10991

Spark plugs, https://1200rt.com/viewtopic.php?t=5.msg28013#msg28013

[David.]

The BMW air filter is £21.16, this Mahle one is £10.07, https://www.amazon.co.uk/d/Car-Filters/ ... B0068NRWYU

The BMW plugs are £13.38 each, from OPIE, they are £8.75 each (4 pack), http://www.opieoils.co.uk/pv-91893-ngk- ... -pack.aspx

Save nearly £30 for the same items.

[Sullivj]

Thank you very much for the links David. I have ordered the suggested plugs and filter, and will report back once fitted.

I found the plugs here for £29.85 (inc. P&P). Hopefully, they pack them as well as Opie usually do...


http://www.ebay.co.uk/itm/221959378051? ... EBIDX%3AIT

Thanks again - that's been a great help.

[David.]

I have ordered the suggested filter.

John, please may I ask, where did you order the air filter from, thanks.

[Lynxfixer]

I had a problem like this on a previous bike, hesitation at a certain point in the revs,  reluctance to accelerate through that point without dropping down a couple of gears first. It was in a 1995 CBR600 which  I know is a completely different type of bike. Turned out to be the charging system (in this case the regulator / rectifier). Took me ages to diagnose, and only found out when I replaced the battery and the symptoms disappeared for a short time. Might be something to look into.

[Sullivj]

John, please may I ask, where did you order the air filter from, thanks.

From Amazon from the link you kindly gave.


I ordered two, to take advantage of the free postage when you order over £20.

[David.]

I ordered two, to take advantage of the free postage when you order over £20.

I'll give you a tenner for one.

[Sullivj]

Sorry. It's already gone to a mate of mine.

[David.]

John, now that you have changed the plugs and presumably the air filter, have you had chance for a test ride.

[Sullivj]

Hi David,


The plugs are done, but I am waiting (still..!) for the air filter from Amazon.


I've left the bike apart, whilst I eagerly await the postman. Once it's all back together, I will test and report back.



As I expected, the plugs looked OK, so I'd be surprised if it's cured the problem.  But at least I've iliminated a possibility, and found some new places to ACF!

[Mac77]

I asked this question the other week, as my 07 (45k miles) appeared to be doing it. I've put it down to the wind! Some days it would be really noticeable, others not so much. When it was bad, it was windy. When not, it wasn't. It's a big old bike and I imagine the wind, when screen is up, hits it head on.