surging

[rooster]

My chim 400 always behaves beautifully except for a minor glitch. About 1 in 10 start ups sees the engine surging. If I switch off and back on again the surging has gone. Any ideas?

[Nuggs]

By 'surging', do you mean that the tacho needle jumps to circa 4,000RPM and then settles back to 900RPMish?

If so, I believe they all do that sir...

[rooster]

no it just sounds like the engine is surging, cannot explain it any other way than it sounds almost like an intermittant very loud purring, only ceases when I turn the engine off and then back on again. It has always done it and even though it is serviced regularly we do not know why it does it!

[Nuggs]

Have you tried cleaning the stepper motor?

www.tvrcc-south-wales.co.uk/stepper.asp

[rooster]

is this the cure to all ills, judging by the posts this morning it is!!!I will do so at the w/e.

[Nuggs]

rooster said:

is this the cure to all ills, judging by the posts this morning it is!!!I will do so at the w/e.

Definitely the thing to start with for any idling etc problems!

I cleaned mine a couple of weeks ago, and the car was sooo much smoother at idle, especially when cold.

Just make sure you have a large enough spanner (the head of the stepper is huge) and don't overtighten the stepper when you're putting it back in (expensive mistake to make)...

[rooster]

Thanks for that Nuggs, hope it does the trick, don't think there is anything untoward but better safe and all that!