weird running issue

[hmmmnz]

Hey guys my fazer runs perfectly at idle and if i blip the throttle it'll rev smoothly,
But when I'm riding it, it'll run on 3 cylinders until about 3800rpm before it come back on to 4 cylinders. And rev smoothly through to red line.
Initially I thought it was carb related, mainly because it was running way worse when I got it, I cleaned the carbs which made it better. It had a missing spring and o ring on the pilot?/idle Screw.

Any way I bought another set of carbs, which I sonic cleaned, and replaced the jets, and made sure they were balanced after I refitted yesterday.  I made sure all the needles and diaphragms were good and were moving freely.

It's certainly made it run even smoother. But the low rpm 3 cylinder issue is still there.

Where do you reckon I should look next.

Cheers

[BBROWN1664]

Low speed under load is where you have the issue.

Sounds like a dodgy plug cap or spark plug

[Frosties]

Low speed under load is where you have the issue.

Sounds like a dodgy plug cap or spark plug

  Just been there with the CBF

[hmmmnz]

Right I'll order a new set of caps and plugs.
Cheers.

[darrsi]

You might find these a bit easier on the pocket rather than £50+ EACH for OEM ones.


A lot of us use them and they're a decent replacement part.


http://www.ebay.co.uk/itm/NGK-SB05F-Spark-Plug-Cap-Resistor-Cover-Black-8080-/271683678476?hash=item3f419bf10c:g:ixYAAOSwpDdU-dZG

[hmmmnz]

funnily enough its exactly what i ordered, i use the same ones on my bmw

[Skippernick]

funnily enough its exactly what i ordered, i use the same ones on my bmw

Now go and wash your mouth out

[hmmmnz]

if it makes it any better its not my only other bike
i like to have an "eclectic" mix of bikes, 
the fazer is the first yam ive had in may a year, my old xz400 put me off yamaha's for a while
terrible terrible bike that,  massively over square bore vs the stroke, which meant it revved like buggery
but nothing really happened,

fazer is doing ok though, a bit small for my 6'4" frame, but foot peg lowering things are great, if a bit frightening if lent over too far

[hmmmnz]

Well changed my plug caps,  2 were at 9k ohm, 1 at 11k ohm and 1 at 55k ohm,  so one buggered, and one probably on the way.
Also changed plugs to grade hotter, from 9's to 8's, not that I think that 9s were an issue,

Will keep you posted on tomorrow's commute.

Cheers for the hand lads.

[hmmmnz]

Much success, lots of joy. Many smooth revs.

Such happiness.

Very smooth ride to work. The below 4k rpm issues have disappeared. Much much better. First time I've ridden the bike with it having no issues.
I'm liking it

[Frosties]