Starting Problems

[Tigger]

Hi Guys, I wonder if anyone has any ideas as to my problem.

My bike always used to start first push of the button, and always has for the past four years, with the exception of a brief period of a knackered battery.

A couple of weeks ago, I noticed the idle speed started to slow down, and then it would not idle at all. At the same time, someone also mentioned that the bike was smelling as though it was running rich. A week ago, it just refused to start on the button. I could bump start the thing, and it would start no problem at all. Once it is running, it run fine, just will not idle, and if it stops, is an absolute git to start again.

I have checked and the battery is fine, so gave it a full service including a new air filter, new iridium plugs and run through with injector cleaner. The bike now runs better than ever, but still will not start on the button.

I am now going to delve deeper into the electronics, and wondered if there is a sensor that operates the choke which may have gone, thus making it run with the choke permanently on, richening the mixture and making it a sod to start, or whether the choke is solely operated from the hadlebar lever.

Any suggestion would be gratefully received

Many thanks in anticipation

Tigger

[du907]

My BMW car did the same thing. Let me check, I'm getting old and I just can't remember what it was. It was something to do with a sensor in the fuel injection. If I pressed the pedal down half way and turned the key it would start. And as long as I keep blipping the throttle, it would run, but take my foot off the pedal and it would idle down quickly and cut off. I'll check my post for the car and get back with you.
du907

[du907]

OK, I went back and checked my BMW car postings about a similar idling problem that was like what you are having with the 907. In the cars case it was a idle control valve. The valve was control electonically and would open slightly letting air bypass the throttle body. It was frozen closed so no air was bypassed and so the idle could not be controlled. I have looked on the 907 and cannot find a similar valve or other like device.

The "choke" on a fuel injected motorcycle is simply a fast idle control. The ECU does all the adjusting, coolant temp., air temp., air density., throttle position, etc. The choke lever just moves a cam on the left side of the throttle body linkages and makes the butterflies open and TPS reads this and sends the position to the ECU and it now knows to add more fuel to match the more opened butterflies in the throttle bodies,(simplified version).
Maybe the throttle cable has slipped or stretched. Just and Idea. Maybe this post will trigger someones memory.
Good luck

du907

[injected]

Does it still bump start easily?

[Tigger]

Hi du907. Many thanks for the suggestions. At least it gives me somewhere to start looking.

To "injected", yes it bump starts very easily, just won't idle, and runs "rich" when it is going!
Many thanks to all, and any other suggestions gratefully received.

I will let you know what the problem was when I have sorted it out................

Tigger

[h1a]

Check the compression, I had similar symptoms on mine, would not start with button but easy to bump start and uneven idle.
Found out I had a burnt exhaust valve...

[injected]

Check the compression, I had similar symptoms on mine, would not start with button but easy to bump start and uneven idle.
Found out I had a burnt exhaust valve...

Yes, that's what I'm thinking too. The 'rich' smell could actually be unburnt fuel....

[Tamburinifan]

Do check TPS position, that is has correct current value, +- 150V.
Sync both thottles.
Correct setting of the CO pot on ECU also important.
Basics first if not done in a long time or by PO.

[Finnpaso]

I quess, that its valve problem. Have You check valve clearances???

[du907]

Did you figure out what the problem was here?