odd engine miss

[birdseye]

when slowing down under engine braking, I get a funny "miss" at about 2500 revs. Its as if the fuel injection is turned off completely above that speed but at 2500 is then turned on again at idle level. So the rate of deceleration momentarily falls sharply and then starts again.

An alternative would be the back wheel sliding except that is happens at just this speed, in all gears and on all surfaces.

Anybody find the same thing? Anybody know if my theory is correct?

 

[GSmonkey]

This is 'surge'. It is cured by a software upgrade, just ring your dealer and ask for the latest software update, they should do it for free.

Otherwise wait until your next service and it will be done as a matter of routine.

 

[birdseye]

Thanks for the reply. As it happens the bike has just (last week!) been serviced and I asked that they checked it had the updates for the injection. They said they would!

You are sure??

 

[ahutcheon]

Is the effect scary, or just noticeable?

On most fuel injected cars from the last ten years or more I've driven (and bikes I've ridden) it's possible to feel this effect. The engine management cuts of the fuel supply (improves MPG slightly) on the overrun until the revs drop, and it's pretty hard to calibrate out the transition entirely.

 

[GSmonkey]

Thanks for the reply. As it happens the bike has just (last week!) been serviced and I asked that they checked it had the updates for the injection. They said they would!

You are sure??

Yes, I'm sure. The syptom is a sudden loss of engine braking at 2500rpm, or there abouts. When you have the software upgrade, the problem all but disappears.

If you've still got it after the service, ask them to check their records. Mine felt like a completely different bike, engine wise, post software upgrade. Nothing that you'd miss.

 

[Mouse]

Mine hasn't had the upgrade yet, but I made the surge far less pronounced by balancing the throttles.

6k service on Friday, so I'm waiting eagerly to see how the bike performs afterwards.

 

[GSmonkey]

Mine hasn't had the upgrade yet, but I made the surge far less pronounced by balancing the throttles.

How did you do that than Mouse??

 

[Mouse]

Very briefly:

Warm up engine to normal temp.

Attach vacuum gauge or manometers to the blanked off vacuum nipples on the throttle bodies. (The bit behind the cylinder head).

Loosen the locknut on the right hand throttle cable where it enters the throttle body.

Increase revs to about 4k, adjust throttle cable so that the vacuum in the two gauges is the same.

Tighten locknut, replace blanking jobbies on the nipples.

It's much like balancing carbs on a non injected bike.

(This isn't the official procedure, just what I did and seems to have had a good effect).

 

[GSmonkey]

Cheers mouse, I'll give that a pop.

 

[Paul Wakefield]

The whole job is a doddle. Even I can do it so it must be. If you can, get (or borrow) a Twinmax.

Paul

 

[Andy Michael]

Is there any way of telling if the bike has had the upgrade from the service print out i.e different software version?. Mine is an 07/05 build bought new in October, had 600 mile service in November, no problems with surging initially but I have had a few "moments" recently which have induced strong pucker reactions in the nether regions.

 

[GSmonkey]

The whole job is a doddle. Even I can do it so it must be. If you can, get (or borrow) a Twinmax.

Paul

I prefer Mouse's idea, which is more in the spirit of the board at the moment, i.e. a manometer aka a bit of tubing nailed in the shape of a 'U' to a bit of hardboard

 

[GSmonkey]

Is there any way of telling if the bike has had the upgrade from the service print out i.e different software version?. Mine is an 07/05 build bought new in October, had 600 mile service in November, no problems with surging initially but I have had a few "moments" recently which have induced strong pucker reactions in the nether regions.

Easy way to tell - accelerate up to 6000rpm in second gear, close the throttle, don't look at the guages. Then wait until the engine has a noticable loss in engine braking, look at the rev counter, if its almost bang on 2500rpm, you haven't had the mod.

Without doing the above, if generally you find yourself nearly going up the back of cars, going to hot into corners and having to *snatch* the brakes at the last minute, this is probably 'cos you haven't had the mod.

 

[chasr]

Thanks for the reply. As it happens the bike has just (last week!) been serviced and I asked that they checked it had the updates for the injection. They said they would!

I bet they didn't; it does take quite a while for a complete software update. Trust me - it gets rid of the surge completely.

 

[Mouse]

I prefer Mouse's idea, which is more in the spirit of the board at the moment, i.e. a manometer aka a bit of tubing nailed in the shape of a 'U' to a bit of hardboard

To be fair, and I know I'm responsible for some great bodges, I don't remember inventing that one I just used manometer as a generic term whether it be home made or not