High Revs on Start-up - FI Model

[alex192]

Hi guys,

Firstly let me introduce myself. My name is Alex and I've been riding for just over a year now. I bought a 2008 Ninja 250r FI model in the summer and I am now riding it to university daily in the cold(ish) British weather.

Now on to my problem-

Whenever I start up the bike, it starts up first time every time and idles around 2000rpm as to be expected for an FI model. However, if I ever rev the bike the engine maintains that rpm even when the throttle is released. For instance, if I rev my engine just after start-up to 6000rpm, it will stay on that and slowly, slowly start dropping back to fast idle.

This is problematic when I first start riding the bike and come to a stop at a junction as the revs are very high. However, the problem soon clears up (within minutes) and the next junction I stop at the revs go back to fast idle when the throttle is released.

Possible problems I have thought of have been-

- Sticking or loose decelerator cable to the throttle, as if I really push hard on the throttle (hard enough to start moving the brake fluid reservoir on the handlebars) to close it when it revs high it sometimes has an effect to reduce the revs a bit. However, this only happens just after start-up and all other times the throttle behaves normally

- Problem with autochoke. I assume the ECU opens a choke to allow more air in on start-up. Could there be a gremlin which is causing it to open too much? The bike has been sitting over summer for ~2-3 months although the bike did start first time after a bit of persuasion with the throttle.

I have just added a Yoshi slip-on which makes the problem even more noticeable, although I have noticed it has been doing this with the stock exhaust also. Also, the bike sometimes falls below the 1300 idle (to about 1000) on warmup when stood at traffic lights, even though the idle screw is set to 1300 when fully warmed up.

Sorry for the long post! Just wondering if anyone has any ideas what might be the problem or has seen something like this before. Cheers!

[BlownWideOpen]

Welcome, try lubing cables

[alex192]

Hi, to be honest I don't think the cables are sticking because I can see the plate which is attached to the cables and throttle behind the fairing moving freely.

The small cam that pushes on the throttle plate, I assume this is for idle adjustment? Because the position of that cam doesn't seem to have an effect on the high revs.

[Alex]

[CZroe]

I don't have an FI bike to compare, but could this be normal behavior for a cold engine? My car does this. If I accidentally rev in neutral as I lift the clutch (thinking I left it in gear) I have to wait a while with the clutch in for the revs to come down enough to shift into the gear I thought I was already in. This is long enough for the person behind me to think I didn't notice the light change. It's not nearly as bad once the engine warms up, but it's still uncomfortably long and longer than any manual car I've owned before this one.

[csmith12]

Welcome! Checked the air filter lately?

[alex192]

I did a quick service on the bike just at the end of summer (new oil, cleaned air filter / breather pipes, new spark plugs (and new ignition coil as one had cracked).

I was thinking the problem might have something to do with the ECU (or equivalent) opening the choke too high. Could a failing battery cause ECU problems?

@CZroe, To be honest I have not noticed anything as bad as this on a car at startup. but it could just be the nature of this engine as the weather gets cooler.

[Alex]

Low batteries cause all sorts of weirdness, but this would be a unique one. Wouldn't hurt to confirm that the cables are attached firmly to the terminals. I'm wondering if it's some type of air leak. Present when everything is cold, but as the bike and its components warm up, the leak has less of an effect due to expansion.

[alex192]

The fact that these bikes have two throttle cables kind of reduces the chances of the throttle sticking open. However, is it possible that the decelerator cable is not adjusted correctly? Does that cable require much adjustment or is it just the throttle cable that requires 2-3mm slack?

The fact that I can see the plate on the throttle return to the idle position makes me think its not to do with the cables but maybe something electrical that controls amount of air into the engine.

[micoulisninja]

Originally Posted by Alex

Low batteries cause all sorts of weirdness, but this would be a unique one. Wouldn't hurt to confirm that the cables are attached firmly to the terminals. I'm wondering if it's some type of air leak. Present when everything is cold, but as the bike and its components warm up, the leak has less of an effect due to expansion.

now Alex (the one and only original one...) has a point there !! the ninjette has been very "touchy" with terminals not being properly attached and/or grounded... you (the other, the 192nd replicate...) did mention changing ignition coil (which I have not heard being a common failure n the FI but maybe just me being lucky...) so if having messed with wiring could be an electric thing...
on the other hand this weird idle-only situation does seem like an air leak working exactly as Alex described... probably one you have not noticed...
a few suggestions as to what it might be and needs you to have checked...
1. sensor out of position or short, especially the KLEEN hosing or IAPSensor...if not properly connected or tapped it will do such odd stuff...check also IAT sensor and airbox, air ducts and head rubbers all being airtight...I suppose you have not removed the snorkel, if you have, place it back...
2. headers tend to need tighening after some working because of expansion too, have that checked too...
3. it is also possible that it's time t have your throttles synchronised... that can be easily done with a proper synchronising tool, fit on the TBs using the screws on top of them...
hope we managed to be of some help... let us know of your progress...

PS... I need both of you to excuse me for my humor, I did not mean to offend either of you...

[alex192]

Excellent, thanks for all the help guys. When the weather gets a bit clearer I will take a proper look at all the hoses and check for any leaks.

On another note, I have noticed that the throttle is very snatchy between being off and just enough gas to keep the bike from maintaining a constant speed going downhill. Is this just the nature of the high revving engine?

[csmith12]

Could be the nature of the bike. Many FI bikes are like that, both my r6's where "snatchy" upon the initial throttle apply. On my street r6, I had the ecu flashed to tone this down. It "mostly" worked. Your chain slack could be out on the far side of loose or you could try shimming the cush drive. Both of those also cause a "snatchy" or "lurching" effect.

[Somchai]

Welcome Alex,

since your bike is a FI-Model without the necessary equipment it's nearly impossible to find the problem (carbs here in this case are so very easy - ).
The first, you need the service manual since you have to measure all sensors and especially those given temperature values to the ecu.
What you call autochoke is a little bit different, since there not the air is regulated but with the engine cold there is more gasoline injected.
It could also be a defect 02-sensor and here too you could measure with knowing the correct electrical values needed.
If you have a Kwaki-Center not so far away, just ask them for help, that's the quickest way.
With a FI-Model the problem could be small as 1 Pound cost but also 100 or more.

Sorry for don't have a solution and good luck for you.

[Hero Danny]

Too bad you didn't have another ECU to test if that was the problem.

[Christofini]

My bike is a 2008 EFI model. On normal days it'll rev to 3-4k for about a minute or two, then settle down to idle (1.1k).

When coming down the mountain where I work, it'll start at 5k and slowly creep up to 7-8k as I coast from the house down to the main road with the clutch in. Within a few meters in gear it's back to normal.

Could you be experiencing something similar? I assume it's because the cold engine is drawing in a lot of cold mountain air with little gas going in, hence kicking up the RPM to keep it warm.

Otherwise, I'd check you have the snorkel in place. When I removed mine I noticed considerably leaner running (EFI can only handle so much).

I'd follow the other suggestions if it is in place.

In terms of throttle, it's definitely the worst bike I've ridden. It's VERY on/off, unlike any carb bike. Feathering the clutch helps a lot.

[alex192]

Thanks for all the advice.

@Christofini , yes my bike experiences something very similar on startup (and only on startup). When I first start up the bike (always starts first time) and give it a slight rev up to 3,000 rpm, when I come off the throttle the engine speeds up to 6,000 rpm by itself and stays there for 20 seconds or so and then slowly comes down again. Recently the weather has been cold (54* F) and this is the first time I have noticed the high idle on startup. If you are experiencing similar conditions then I hope it is just the nature of the bike.

If there was a vacuum leak somewhere would it affect performance on a warm engine or just on startup? Also, there is no history of the bike having its valve clearances checked and it has done 17,000 miles. The bike sounds good at idle. Been meaning to do the valves for a while now but haven't found the motivation to do them. Maybe this has an affect?

[Christofini]

Originally Posted by alex192

Thanks for all the advice.

If there was a vacuum leak somewhere would it affect performance on a warm engine or just on startup? Also, there is no history of the bike having its valve clearances checked and it has done 17,000 miles. The bike sounds good at idle. Been meaning to do the valves for a while now but haven't found the motivation to do them. Maybe this has an affect?

No idea about the vacuum leak. I assume it would cause an erratic idle / rpm surge while riding?

About the valves - I bought my bike used with 12,000km (about 7,500 mi) and was told it had valves done. I checked them at 24,000km (about 15,000 mi) and found my exhaust were practically shut. Intake were in the lower range of recommended specs.

You won't hear tight valves (AFAIK), only loose ones. If you notice long cranking or high engine temps they're likely tight. After I did mine it starts with a tap of the button, whereas before it took 2-3 seconds.

It doesn't take much to inspect the valves (there's even a guide here). Definitely worth doing if you're unsure.

[dooby]

Hi Alex, nice to see another UK 250R rider :-)

I notice the same high-revving as you sometimes on cold starts and I have to say I have come to assume it is somewhat normal. If it bothers me at traffic lights then I keep the bike on the brake and gently release the clutch into the friction zone until the engine starts to struggle against the brake and lowers the revs. I find it will usually settle at the lower revs then and I can fully engage the clutch again.

I have also suspected in my case it might be partially caused by having heated grips, I suspect the increase in current draw may also add to the engine seeing more load from the alternator and trying to compensate.

Regarding the choppy throttle at low openings I thought that was normal on FI bikes and got used to working around it. When I fitted my Power Commander V, even the stock map was *much* nicer, it felt like a new bike! If you're considering other performance mods it might be worth bearing in mind.

I recently adjusted my valves for the second time at 15,000 miles and I had been getting a slightly noisy tapping at idle which would somewhat go away under load - this has now disappeared since I re-shimmed. In my case I think I found all of my exhaust valves were heading out of spec.

HTH, Pete

[alex192]

Hi Pete, thanks for your input. Yeah I have now accepted that the high revs are normal and usually rev the bike when I'm putting my helmet / gloves on and by the time I get on to ride the revs have dropped. I think it is only bugging me now since I installed my new Yoshi slip-on, but I'm getting used to it.

I think I will do a valve adjustment soon. How did you find getting shims in the UK? Did you buy direct from Kawasaki or buy generic ones online?

As for the choppy throttle, it is something I am just getting used to. Out on the country roads and the bike is a lot nicer to ride, which I suppose is what it was designed to do.

[dooby]

Hi Alex,

I found these UK stockists of the HotCams shim kit so decided I'd buy them all and hope never to need to order again...

http://shop.1stmx.co.uk/valve-shim-k...ikes-485-p.asp

It was a bigger outlay, but price per shim was a lot lower.

HTH, Pete