Mk1 Nexus buyers guide?

[Taipan]

Thanks Michael. Some real good advice there. I topped it up with BP Ultimate last nigh and its run a lot better today and hasn't cut out at all. So maybe the magic fuel cured it or more likely it was just a glitch of some description?

I'm wondering about the IACV stepper motor now. I recently sold a F800 BMW after getting sick to death of it cutting out due to the IACV (idle actuator control valve). I'll have to look into this in more detail. I'm stuck for doing anything until that coupling arrives from Piaggio Via Suttons. Its not in good shape and I suspect its still letting air by. Sadly I'm only 10 days into a 21 day order time. I think once I have the new coupling I'll have the throttle body out and clean it and anything else that looks dirty!

If its running lean it might be killing the plug? So I'll put a new one of them in anyway. I cant wait for the coupling to arrive so I can clean check things and get that damn EML out. I'll get the codes read at scootech if need be. Tempted to do that anyway but with possible inlet air leaks its not worth doing until that's done I suppose.

[michaelphillips]

yes i think it needs taking off , get advise with what you can squirt into the throttle body, prob carb cleaner, not sure if a petrol additive for injector would help if clogged with the dirt getting in, some photos of the throttle body to see what you looking at: this one the only one i could find for sale in italy with an offer price they want £70 delivered but you could get it down a bit, anyway worth watching.
http://cgi.ebay.it/ws/eBayISAPI.dll?Vie ... 4047wt_952" onclick="window.open(this.href);return false;

you can see the connections, and the workshop manual states

Intake system cleaning
Air filter ( have a look at condition)
Diffuser and throttle valve
Additional air pipe and Stepper ( the throttle body may have this additional pipe on and may be clogged, i know carbs have an air pipe and if that is blocked fully it starves the fuel mix, so could be slightly blocked......

Intake system sealing (infiltrations)
Intake manifold - head ( could all need re-sealing)
Throttle body - manifold
Intake sleeve
Filter box







so gaskets or use whats there and gasket sealant, hope everything works out

what the manual states regarding throttle body:
THE THROTTLE BODY IS A PART WHICH INCLUDES VARIOUS COMPONENTS AND IS USUALLY
SUPPLIED COMPLETE. TO TEST THESE COMPONENTS SEE THE "INJECTION" CHAPTER.
to take off Remove the 3 retaining screws
CAUTION
THE THROTTLE BODY COMES PRE-CALIBRATED. TAMPERING WITH THE THROTTLE STOP
REGISTER IS TO BE ABSOLUTELY AVOIDED. THIS REGISTER HAS BEEN SEALED FOR THIS
PURPOSE. FOR PROBLEMS WITH IDLING SEE THE "INJECTION" CHAPTER.
N.B.
REMOVAL OF THE THROTTLE BODY CAN BE EFFECTED WITH THE MANIFOLD ON OR OFF
THE ENGINE.
Make sure the seal rims on the coupling surfaces
between the manifold-throttle body and manifoldhead
are in good condition.
CAUTION
IF AIR GETS IN IT CAN JEOPARDISE THE OPERATION
OF THE INJECTION SYSTEM, ESPECIALLY
WHEN THE ENGINE IS IDLING.
Make sure the throttle valve and related conduit
are clean.
- Make sure the supplementary air channel managed
by the stepper motor is clean.
N.B.
IF THE THROTTLE BODY IS REPLACED with another one, RESET THE T.P.S. AND ADJUST THE CO%.
ONCE THE ENGINE IS REPAIRED CHECK THE CO% VALUE WHILE IDLING TO MAKE SURE IT
IS WITHIN THE PRESCRIBED VALUES.
Upon analysing the material sent and covered by the warranty, it seems several throttle bodies have
been mistakenly replaced due to valve fouling. Dirt deposited on that valve, mainly on the inlet manifold
side, can be easily removed. Once clean, the throttle body guarantees an air flow exactly the same as
the original. Throttle valve fouling is phenomenon that happens at different times depending on how
the scooter is used, weather conditions and idle speed adjustment. This phenomenon can be easily
detected as a gradual poor idle signals it. Carry out a thorough check


Standard Dirty throttle body
Engine revs 1500±5 < 1400
Ignition advance 5°÷7° 10°

it could be worth buying a petrol additive to clean injector and intake valves from deposits
STP Petrol Treatment 200ML


Specially formulated to improve engine performance and reduce fuel consumption by fighting the build-up of harmful dirt, gum, varnish & deposits in the fuel system.

For best results use every 1,500 kilometers.

Safe for catalytic converters.

STP Petrol Treatment, used regularly, helps:

Keep carburettors and fuel injectors clean
Reduce intake valve deposits
Fight rust in the fuel system
Reduce petrol consumption
Reduce exhaust emissions
only a thought as if you waiting for part you might as well start cleaning the internals before dis assembly if you still using scoot

[Taipan]

Wow, again great info, thanks! The difference a stepper motor (IACV) valve makes is so subtle but yet a right pain. Here's two videos of a working one and a faulty one. They cycle when you switch the ignition on and again when you switch off. You can hear the second one struggle slightly, barely any difference but its night and day to the bikes running!!

[BBvideo 560,340][/BBvideo]

[BBvideo 560,340][/BBvideo]

[michaelphillips]

yer cheers see what you mean, im on a learning curve as well, just in case HaHa

Hopefully with the seat off when you do it, and receive the new pipe it all falls into place, grab yourself a tin of Hammerite Black Direct To Rust Satin Paint, as i found when doing any strip down the frame gets a good going over and you dont have to prime the rust, just some cheap thow away brushes
so if im honest my frame has virtually all been done
cheapest i found stp is £3.94 delivered not sure what price in garage http://www.ebay.co.uk/itm/111048753597? ... 1439.l2649" onclick="window.open(this.href);return false;
the only job i keep thinking of doing on mine now, is adjust the valve tappets but no access, ive tried, could not even get the cover off!!!! i think you have to drop the engine .... so i wont be doing that

[Taipan]

Well I went to France and it behaved okay but did cut out on idle a couple of times. But on the way home it spluttered and cut out and wouldn't start. I rolled back down the hill into a village and found out I didnt have an allen key to get the side panel off to see if I had a spark. Really pissed off with myself at this point for not checking the tool kit. Ho hum.

I try to start it again and now the battery is dying. I know my mates are heading for the ferry as we're running late. so I have to wait thinking they'll be back. Unbeknown to me they think I'm in front! After 20 minutes I think I'll disconnect the battery and reconnect it just maybe it will reset something. I dont if it was that that worked but it started gain.

I then ride the remainder of the D940 to Calais like a maniac. I dont dare stop in case it cuts out again. So when I see my mates at the side of the road (phoning me apparently to find out where I am), I slow down a bit and just shout cant stop see you at the ferry. I saw one of them say what the... but I was gone.

So the bank holiday will be spent stripping out the throttle body...

[michaelphillips]

Glad you had a GREAT TIME bet your mates were grinning when you told them... just a thought....make sure its not a champion plug you have in, i got a new one in some bits that were ordered from previous owner from suttons when i bought the scoot 2 years ago, as i thought i would put it in mine, only lasted a day, thought i would try it....it stalled on deceleration twice, so whipped it out and binned it....
aso just a thought: sounds like its a starvation of fuel as air mix too high so scoot electronics are having a paddy with your mixture....
the scoot must have liked france, wanted to stay there

[BenR]

I use the NGK iridium in mine mainly because you don't have to change them (they last 40000miles) but also there's no fade in performance when the bike gets hot. If you need a new throttle body I have a clean spare £30 + P&P.

[michaelphillips]

I use the NGK iridium in mine mainly because you don't have to change them (they last 40000miles) but also there's no fade in performance when the bike gets hot.

i used the NGK iridium they are good, i switched to a Brisk Racing Performance AOR14LGS Premium plug about 6 months ago, it uses a silver core which is supposed to be the best conductor, and 3 electrode grounds, should last the life of the scoot, and its superb and the minimum throttle hold is amazingly stable compared to before, i would highly recommend.

[Taipan]

As I've been away on a jolly boys outing the wife isnt too pleased about me working on the bike today, but I just wanted to have a quick look at the throttle body. It was black as soot and I mean black and sooty! I squirted it with cleaner for and saw the little sensor whatever it is, this side of the butterfly came up white and clean. Clearly it needs to come off and be cleaned better but I promised thewife I'd take her out or she'll sulk.

As I'd blasted loads of cleaner in there I thought I'd best tke the plug out nd spin her over in case it hydraulic cloks. Good tip is not too look at the plug hole when you're doing this as I got a facefull of Triple QX!

On the plus side the plug is a NGK cr7ekb and looks a perfect colour. Not seen one of those type plugs before?

[michaelphillips]

black soot can only mean carbon deposits, so must have a leak somewhere, have a great day with missus, im having a barbie later with the kids