Fork Oil Replacement

[NTECUK]

Next. Cartridge emulators?? ??

Rear shock next. Tyre shows unusual wear due to suspension. But I also need to have a look and try figure out this 'lurching' at slow speeds issue.

[Bibio]

try and explain the 'lurching' is it a constant pulse at a constant speed or is it when your on and off the gas?

It's when I hold the throttle steady at 20/30 in 2nd/3rd respectively around town. It feels like it's missing or hesitating but the exhaust note doesn't change and it doesn't affect my speed. It is definitely there though, but I'm not sure what it might be. I did oil, coolant, filters (air/oil), front forks, TPS down to 1500 and TB sync which vastly improved the throttle response, but the problem is still there. Puzzling. I don't know if it's normal (as I've not ridden another SV), my suspension, or an engine problem. I don't seem to notice it at 40+ in 4th and above.

EDIT: Oh, and the spark plugs are less than 3 months old.

[Bibio]

first is to check your brake discs. pop the front end up on a stand then turn the wheel, if there is any high points (e.g. turns free then binds up) then your disc rivets are needing cleaned out.

if its not your discs then next up is to try your chain for an over tight spot. pop the rear of the bike up on a stand and turn the wheel checking chain play every 15cm or so. if your chain goes from being slack to being tight then its new chain time. chain slack should be just about touching (15-20mm) the underside of the swingarm at mid point. if its tighter than that then loosen off your chain.

apart from a coil kicking in and out then there is not much else that will cause the problem you are having. only other thing i have heard of is a knackered TPS sensor.

I'll have a check with those things and report back when I can. Chain isn't that old and I've kept it pretty well cleaned and lubed, but will check everything.

What are the rpms at 20/30 mph in 2nd/3rd gear? My first thought is, rev it up a bit.

Haynes probably just grabbed a generic pic for damper rod fork disassembly, at least the part where you remove the springs ans spacers and dump out the oil.

(Please move this if it's now in the wrong section. Wasn't meant to be a tech help thread).

So... I figured out the lurching... when my bike broke down just off the motorway at Southampton. Had to get a van back today... 2nd time in 2 and a bit years and I think I might have a solution, (though again please tell me if I'm being thick!)

Slowed down at some lights, monster backfire (felt it through the bike, though it wasn't loud due to the stock cannon/exhaust), clutch in to 1st, engine cuts out. Thumb the starter, dies immediately. Repeat, same result. Get it started and hold the revs at 3k and it burbles, judders a bit and hunts, randomly revving up and down, cuts out once more at a junction. I had to keep the revs at 3k to stop it stalling. I think it was running on one cylinder at times from just off the motorway to my friends house. The exhaust smells strongly of petrol and it's still missing at idle (lumpy too) and holding at 3k it was hunting again today. Got a lift home from a nice breakdown man and van.

(Long read, sorry...)

So, I don't suspect 2 fuel pumps to be the case, and having read this:

Fuel injected engines also rely on intake vacuum to regulate the fuel pressure behind the injectors. Fuel delivery cannot be accurately metered unless a fairly constant pressure differential is maintained. So the fuel pressure regulator diaphragm is connected to a source of intake vacuum. Vacuum working against a spring-loaded diaphragm inside the regulator opens a bypass that shunts fuel back to the tank through a return line. This causes the fuel pressure in the injector rail to rise when engine load increases (and vacuum drops). Thus, the regulator uses vacuum to maintain fuel pressure and the correct air/fuel ratio. A vacuum leak changes the equation by causing a drop in vacuum and a corresponding increase in line pressure."

I noted those symptoms are exactly what I had last time, and again now this time. The first time I had it investigated, it was noted my fuel lines were running way over pressure, as in 80+psi instead of ~43. BUT, the SV doesn't have that system, it just has the spring loaded valve on the fuel pump itself. So, any thoughts? ECU? HT leads? Alternator? Another pressure release valve is faulty? Something else?

Thanks all!

PS. Plugs are around 4-5 months old tops.

Rear plug is wet, black and smells of fuel! Update this post when I get to the front one.

Front is black and smells of fuel somewhat but isn't actually wet.

RAM

I would be inclined to do a quick compression check whilst every thing is apart just to be sure the engine is in good fettle.