Sparkplug Problem

[savfr]

Hi
I’m having a dilemma with my plugs. I have a set of denso plugs and a set of NGK 9eh.
With the denso my bike has a problem when i start it in the mornings, (Choke no throttle etc... become a master at it) is starts fine the after 2 min the revs drop and it dies. The only way to restart it is by jump start, then its fine. With the denso's i have a small flat spot of about 200 rpm just after 6000rpm and the bike runs cooler.
The NGK's have no problem with the starting routine in the mornings, but i have a large flat spot from 5500 rpm
to 6500rpm and the bike runs warmer.
Has any one had this problem before??? or have a solution?
Thanks

[wullvfr]

seems a little strange......

i have run both sets in my nc30 and i can say i have not experienced this.
i also did not notice any difference in the temp,whether or not there was a difference as i may have just not noticed.
i have heard of people running different denso spark plugs in no.1,4 cylinder to the denso spark plugs used in no.2,3.

something to do with the rear two cylinders getting hotter but i can not confirm this.
do the plugs spark ok?and is the electrode gap as it should be?



william

[savfr]

Hi William
I checked the spark and all is fine , i also check the plug burn on a chart and they seem to fine. The Gap is 0.7 mm within spec 0.6-0.7 mm
I think i should try 1-4 denso and 2-3 NGK ??

[Neosophist]

You should only use the choke for max of 30 seconds unless the temp is in the minus' and then turn it either all the way off or down to very minimum otherwise you'll fowl the plugs, and the bike wont start.

2 mins of choke will kill me bike.

[savfr]

Hi Neosophist
if i try that then the bike just floods when i open the throttle.
It won't idle without the choke after 30 seconds. It takes about 3 min before its warm enough to idle.

[Sligeach]

i think neo is saying relax the choke off after 30 seconds, not turn it off fully, just relax it off so the revs are still holding around 2.5

[Neosophist]

i think neo is saying relax the choke off after 30 seconds, not turn it off fully, just relax it off so the revs are still holding around 2.5

Aye :)

When was the last time your carbs were stripped and overhauled? If its taking that long to come off choke you may have clogged slow running jets.

I can take mine off choke after 30 seconds, granted it still runs crappier till its warmed up but it'll tick over (albeit lower rpm than warm) without choke.

I'd recommend a strip / clean of the carbs, cheaper than new plugs (which I suggest if the carb overhaul doesn't work)

[savfr]

Thanks
i'll give the carb clean a go this weekend.

[Neosophist]

be sure to remove all the jets and give them a good soak in carb cleaner and proper blow out with some compressed air (work on 1 at a time to make sure you dont' mix bits up)

theres no need to separate the carbs either :)

[savfr]

should i also look at drilling the carbs and adding the washer to reduce the flat spot and making it more throttle responsive ??