Slight hesitation from tickover as you open throttle

[garfieldus]

I have a slight hesitation when moving off from a standstill over a rev range of about 150 rpm. It's a real pita when approaching a bend or a roundabout when blipping the throttle while shifting down and in fact it has cut out on me a few time in those circumstances which is a very big pita.

Here's a video...

https://www.youtube.com/watch?v=qCnDBYZNc5s

...I'm doing it very gently to demonstarate and hopefully you can hear the hesitation as the revs begin to build.

Can anyone help me to fix this?

[swamper]

How long have you ridden this bike?

[garfieldus]

How long have you ridden this bike?

Not long. I collected it in Germany in December 2019 and it developed this fault half way through France on the way home. It's been sitting in the garage throughout the Winter.

[swamper]

I'd run a couple of tanks with Techron additive and see if there is any improvement. Plugs and Valve adjustment could need attention but try the Techron first.

[riceburner]

My first thought would be fuel flow.

[garfieldus]

Thanks for the help so far lads. New plugs and air filter, no difference. I'm borrowing two known working stick coils tomorrow to see if it's either one of them. I do have a spark from all four plugs but not sure if the spark is good enough. I'm really hoping it'll run perfectly with them in even though they're pricey at least it'll be sorted.

It looks like I have the original coils. It's a 14 year old bike but with only 48k kms on it and like the rest of the world I cannot get out in the beautiful weather we're having at the moment in Ireland to put a couple of tanks with Techron through it

[swamper]

Coils usually work or they don't.
It sounded more like a fuel delivery issue to me, that's why to clean the injector system, cheapest try also.

[sstein]

Just saw your video. I sort of have a similar problem, especially if blipping the throttle AS THE RPMs NEAR IDLE. I have also almost had the engine cut out on me.

One thing I notice on your video is that your idle is low - around 1000 RPM. I thought it was supposed to be more like 1200-1250 RPMs?

Others on this site would probably have a better sense of whether that may be an issue.

Good luck.

Steven

[garfieldus]

Just to give some closure to this thread...

The problem turned out to be incorrect cable free-play at the throttle bodies. BMW recommends 2mm. One had no play and the other had .5mm. Both were adjusted to 2mm and the problem immediately disappeared. Followed up by a sync of the throttle bodies with the TwinMax and it's running sweet now.

Thanks for all the help.

[CycleRob]

Listening to the audio I can hear one cylinder not running as the throttle is applied and I can guarantee it was the right side TB with no free-play -because- the right TB opening would only add more air while the left TB throttle where the TPS switch is mounted remains at idle mixture. Besides that, with any throttle related irregularities a TB synch is the first thing to check.

For the most accuracy of any Synchronizer, make yourself a differential water manometer (water stick) using distilled water mixed with food coloring + about 20 percent by volume Isopropyl Alcohol (for sterility). Be sure to keep the hoses mounted on the wood close together for accuracy and fill it to the tape marked total length using incremental tongue throttled mouth suction (stick inverted) for 2x the mid point height + the bottom loop length. Gravity will tell you how to do it right with 1 or 2 attempts.


Its' one short coming is that it is so sensitive that an errant synch will suck the water out as you start the engine, so fold kink one hose before starting and slowly release it to check for being close enough to use.