Carb clean/cold running/fouling plugs?

[Weebl]

Ok, quick backstory.

Bought a bike recently which has been stood for a long time (circa 5 years)

It fired up ok, so sorted the valve clearances, serviced it and MOT done no issues.

Rode it then for a day or so but it got progressively worse, stumbling and failing to fire, culminating in a refusal to start. I then realised I had been lazy and because it was running ok, I ignored the fact that the tank was full of crap from where it had been sat. (no fuel filter on a GPZ500)

Stripped the carbs out, cleaned them (they were minging) reset the pilot needles, checked the float height, all clean and shiny, put them back in, fired up fairly quick, redid the carb balance, put an inline filter in the fuel line, job done (so I think)

sat idling for a while whilst I went and put my kit on, as I got on, the revs rose to 4k (I had fiddled with the idle screw to get the idle sorted while doing the carb balance) Had a little ride to see if it would settle, nope, lowered the idle screw and all set again.

Went for a blast, while hammering up and down the dual carriageway no issues what so ever, went like a steam train, big grin. Went into town and had a trickle around, as I came out of town she started missing again. Felt like either fouled plugs or no fuel again. opened the throttle and tried to give her a little spank to clear the plugs while also trying not to drive like a knob in a 40 limit. Cleared after one redline, and rode home again fine?

Now according to the temp gauge she runs a little cold, pretty much never going much higher than a quarter of the gauge high (and these bikes have a rep for running very hot?) the engine felt hot enough, not 100% sure if it is just a low reading gauge or is actually cool running.

The question is, is it likely I have cocked something up on re-assembly leading to the idle going from 1.25k to 4k and needing winding back down? Is it running too cold, and too rich, which is causing the plugs to foul at low revs? Does it need leaning off or should I put a set of hotter plugs in to compensate for it actually running quite cool? Is it ok and I just need to let it settle for a couple of miles?

Sorry for the long post, if I write it all down it helps my thought processes, but any suggestions would be welcome.

[TC]

Ref the revs going from 1.25 to 4k at idle and needing the needle winding down to sort it this out.

I had that problem and it was the Choke sticking, might be a starting point until someone else comes along with something else.

[Weebl]

Ref the revs going from 1.25 to 4k at idle and needing the needle winding down to sort it this out.

I had that problem and it was the Choke sticking, might be a starting point until someone else comes along with something else.

 

Cheers. I did not specifically check this but as I was riding and doing a bit of 'hot fault diagnosis' I gave the choke a tweak (and the engine bogged immediately) and then pushed it straight off and she picked straight back up again. It may well have been the initial issue though so I will ignore that symptom for now and concentrate on the rest

I have just thought of another issue though Going right back to basics I checked the NGK website for the recommended plug for my bike to make sure I had got the right one. I did, but then remembered my bike seems to have a later engine in, which is specced for a different plug, but it has an 8 in, and the later engine is specced for a 9. so colder, which would make any fouling at low revs problems worse?

[Weebl]

Oh well, looks like the last option 'do nothing and see if it is ok' is the winner. Just did 80 odd miles this morning, mix of riding, and she did not miss a beat.

Big grin again