Running problem driving me nuts!

[Blapper]

Hi Guys,

So, I moved house and the new house was a massive renovation job which took me 2 years 2 months to finish. When I finished the house, I taxed and insured my 2001 SV650S for some me time and fingers crossed, tried to start it. It had been stored in a warm dry garage for that time. The battery was fine because it was on an optimate, so it did start but it ran like a pig with popping and banging in the exhaust and spitting back through the carbs. I shut it down and chucked away the dodgy petrol that smelt stale and put new fuel in it. I took the carbs off and blew them through with carb cleaner and my airline. It ran a little better, but still not right. I took the carbs to my local suzuki mechanic who stripped and ultrasonically cleaned the carbs (twice) and gave them back looking brand new. The bike runs better. It pulls like a train and is smooth as silk after about 1/8th throttle but when ticking over is plip-plip-popping quietly in the exhaust.

It is a 2001 bike in super-clean condition and has still only done 15500 miles from new. It has 7000 mile-old iridium plugs in it. I have so far disregarded any kind of HT related fault because the problem is only there on a tiny throttle opening and goes away completely after 1/8 throttle. Usually HT problems get worse as he cylinder pressure goes up in my experience.

Now I love my SV, but as it is fully faired, it is a lot of work just getting the damn thing stripped and drained down so I can see the job and having done it three times now, it is getting right on my tits I can tell you. Can anybody give me suggestions based on their SV experience on what this can be please?

I will be unbeleivably grateful if anybody can give me a pointer on this!

Thanks guys.

[Biker Biggles]

Pilot jets blocked will cause poor running at tickover and just above as will choke plunger/choke cable issues. The other thing that springs to mind is a slight air leak in the intakes which becomes unimportant when the revs increase. Does it have the OE exhaust and any leaks in that? A good overdose of redex or similar and a long ride to include an Italian tuneup can help too.

[Blapper]

@Biker Biggles: thanks for your reply. Our minds work the same way. I took it apart the first time expecting to find blocked jets after standing two years, and found one but it was a main jet and I cleared it. I tried your 'Italian tune up' (120 in a flash). I too thought an air leak in an intake becoming less important at higher vacuums. I'm having one last go over the next couple of days, so I will pay extra attention to the choke plungers. It starts from cold ok, but a new pair of o rings there won't hurt. The Suzuki mechanic thinks HT cap but I don't. I will change it if there is enough lead and if it isn't moulded on. Are they moulded to the HT lead and coil?

[Bibio]

have you checked that the vacuum bungs have not come off the spigots or a loose/kinked vacuum hose?

have you balanced the carbs?

[R1ffR4ff]

Still check the Plug caps as per,

https://cx500.000webhostapp.com/SV65..._And_Caps.html

Also I tried some Iridium plugs and my 99 ran OK but not as good as stock Denso or NGK. According to research Some Iridium plugs can cause a different,"Dwell Angle" if not designed for the engine.

[Blapper]

Hi @Bibio,

I am taking it apart today and will look at the bungs, and mechanically the carbs are balanced, yes.

As I said, the damn thing ran absolutely perfectly on the smallest of throttle openings before it stood.

Hi @R1ffR4ff,

Good tip about the Iridiums as that is what is in there. I have new standard NGK's on order.

Your hyperlink doesn't work?

Are the HT caps moulded on? The new NGK cap that I have is straight and I am concerned the lead might not be long enough after removing the old cap.

[R1ffR4ff]

Mine were not moulded on.

Link works for me. Can you try another browser?

Try this short version,

https://bit.ly/3zhNKAy

The plug caps I used are red NGK SD05FMR for the red and or Black,

NGK SD05FMB for the black

https://www.ebay.co.uk/sch/i.html?_f...5FMB+&_sacat=0





The piece of Card on the Radiator is for temporary protection of the Radiator Fins and my Knuckles whilst I work on the front Plug/Area. To make it easy to get to my Front Plug I have removed the Horn Bracket and moved the horn to the front left of the bike. I can now just remove the 3 Radiator bolts and force the Radiator forward to gain access to the Front plug without having to remove the Coolant.

I made the skirt/grommet out of some old inner-tube and you can make another square to go on top to be belt-and-braces against rain/moisture and curd ingress but also make sure drain holes are not bunged up.

[Blapper]

Ugh, I'm still getting 404 on edge and chrome.

Anyway, I've changed the ht cap now, so we'll see if it makes a difference. The plugs look lovely (clean and colour) and similar too.

Bungs and pipes are all sweet.

It has a fuel can on which plips and pops on the over run, but is has never, plipped and popped on tickover before.

Gah this is annoying.

[R1ffR4ff]

It could be a fault with the ACV (Air Cutoff Valves). They are called something else on the SV.

Parts 34 to 36 on here,

https://www.suzukipartshouse.com/oem...07f/carburetor

They enrich the mixture when the throttle is closed to prevent a weak mixture from causing popping when the the throttle is closed on CV carbs.

Also any Air-leaks into the carbs can cause your symptoms as can exhaust leaks.

If it is the ACV I think these are the ones but more research needed to confirm,

https://www.bts24.co.uk/en/engine/fu...ml&language=en

[embee]

Plugs will only affect the burn initation (0-5% burn, what you refer to as dwell angle, not really a strictly correct term) if the projection is not what the engine was calibrated with.
I know some cases where a true like-for-like iridium is not available and people fit a near match, and this can indeed lead to some issues (a 700 Deauville for example uses a projected nose std plug but the nearest catalogue iridium is a non-projected, and this can cause some cold starting/fouling issues. There is however a platinum direct equivalent but it needs a new plug cap due to a fixed terminal rather than screwed. They run perfectly on that platinum version).

Strangely I had an issue with some iridium plugs in my curvy, much as you describe. It would run under load but not just off idle. I interpreted this as a fuel problem, as discussed by the OP and others. Having tried all the usual stuff I ended up fitting some old std plugs as a last resort and it ran perfectly. I have not come across that problem before except on lawnmowers, and then after numerous drainings of carb etc a new plug fixed it. It doesn't really make a lot of sense, as you already said regarding cylinder pressure/spark voltage requirement, but it happens.

I fitted a new set of iridiums in the curvy and it has run faultlessly since. A pair of std plugs are cheap and will answer the question.