Limp home mode

[Aether]

So I've just cleaned out the carbs and checked the valve spacings, got everything back together and went for a ride. My god it felt better, much cleaner through the revs, and pulling really well until it started spluttering and cutting out, I looked at the speedo and it wasn't working at all. So I'm thinking this is Limp home mode? I've taken the speedo cable off and it looks like its turning both ends, so I've taken off the Kph/Mph convertor and put the cable straight in. Still nothing. Any ideas?

[wullvfr]

the limp home mode should affect the running of the bike at around the 5000rpm mark,it cuts the spark to the rear two cylinders causing a bad mis-fire.

is this what you are experiencing?




william

[Aether]

Yeah. It had been running really well and then just starting spluttering and hesitating, I glanced at the speedo and it wasn't working, but every now and then it would pick up again and the speedo would work for a second or two then cut out again. It won't start now
I'm thinking it's got to be limp home related no?

[wullvfr]

it does,but the bike should start!!!!!

check the wiring at the back of the speedo at make sure it is all well and good.

if the bike continues to not start,then check to see if there is any spark at all....




william

[Aether]

Thanks William,

I think that maybe I flooded it when it started playing up? Anyway, I'll have a look at the wiring and hopefully get it sorted and go for a ride!

[Cammo]

I glanced at the speedo and it wasn't working, but every now and then it would pick up again and the speedo would work for a second or two then cut out again. It won't start now

The speedo is mechanical, only driven by the speedo cable. If the speedo isn't working then it's likely that the plastic drive at the gearbox end of the cable is worn.

Like William said though if the wires aren't plugged in properly at the speedo it can cause running problems (not speedo problems though).

[Aether]

I'll have a look at that Stickshift, thanks.

It's so annoying, I got everything back together with no drama (I'm a complete mechanical novice) and it was running so sweetly and then splutter, splutter I will sort it tomorrow

[Sligeach]

the cable may be turning but there is a nylon "thingy" into which the speedo cable attaches into at the bottom end of the cable and sits over the nut which secures the front sprocket, this may be rounded resulting in the lack of reading

[Aether]

Hi Declan,

I take it this is what Stickshift is talking about too, this'll be my first port of call tomorrow. I'm hoping it's as simple as this being worn and not a symptom of my handywork.

Cheers guys

[Cammo]

Sounds like a fuel related issue to me.

Check the fuel vacuum hose for kinks/splits etc. This is the thin hose that runs from the fuel tap below the tank to one of the inlets below the carbs.