Zx7r bogging, won't idle etc

[R84]

So I have an issue with my new to me 7r, I took it out today after being sat for 4 days. I had previously noticed a bogging when cracking the throttle in 1/2/3rd, but it wasn't too much of an issue.

Started on the button today, got about a mile down the road and notice the idle speed is dropping and dropping, it stalled at some lights, managed to restart it and decided to keep the revs a little higher without looking like an obnoxious ****... Away from the lights got barely any power even on WOT, bike lurching everywhere and didn't want to rev. Died again and wouldn't start. Pushed it to a parking space and let it sit for a while. Gave it full choke (choke appears to have no effect whatsoever on this bike, it's started on the button with no choke thus far) and it sounded awful, a couple of pathetic pops, played with throttle, half open, fully etc, eventually managed to get it started and get back home by keeping the revs high.

Any ideas as to what the issue could be? Battery was new, bought just before the bike was sold to me 3 weeks ago. Seems okay if you manage to start it and not let the idle drop too much, it was around 500rpm left to itself. I have since read there's an idle screw I can adjust but if the bike was fine for the 200 miles I've ridden it so far would that be an issue? It used to idle fine. It's due it's 15k service so I might get them to take a look. It has a dyno jet kit apparently which I want to replace with a factory pro kit when I've got an akra can to fit my akra headers. Got a yoshi GP force on currently.

My thoughts were to limp to the dealers, thinking throw some redex in the tank and play with the idle, but there are clear problems here. Any ideas? I'm mechanically minded as far as servicing etc but have no tools where I'm staying at the moment. Also never tackled carbs before...

[CaNsA]

Sounds like blocked carbs/water in fuel/dirty fuel filter

[jaffa90]

As said, check fuel supply and carbs if fitted.

[ssray]

Common fault is the fuel pump, bypass it and see it its still there
It`s a pain to do as you have to take the tank off, I did mine with a torch and a few tools roadside 3 days after getting my 7r.
try some in fuel carb cleaner or shell posh fuel that contains no ethonol

[temeluchus]

Don't fiddle with any adjusters.

Try draining the float bowls first, each carburettor has a drain on the bottom so you can dump the fuel out. You can then check for water and crud.

Then start looking at pumps, cleaning carbs etc.
____________________
Some shite cruiser. Now with guns and FREEDOM!

[RhynoCZ]

Might be a shot in the dark, but when was the last time you checked the alternator (bearings, brushes)? The alternators on the ZX7R's are like the ones used in cars today, not the typical motorcycle alternator. Meaning, more load = more torque is require to spin the alternator. Which at low revs idle could result in stalling, when you turn on the lights, the brake lights light up etc.
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'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor

[R84]

Thanks for the replies.

[CaNsA]

[R84]

[RhynoCZ]

I only suggest the alternator, as your motorcycle is old enough for a alternator brushes/bearings change. My ZX7R was stalling when, for instance, I got to a intersection and squeezed the front brake lever, the brake light turned on and the engine stalled. The idle was about 1,200 rpm (should be between 1,100 and 1,400 rpm). When ideling with all the lights off, there was about 1,200 rpm, when I turned the low beam, high beam and brake light on, plus the turn signal, the idle dropped by 100+ rpm. That caused stalling at some random ocasions.

Quick fix (that I did): I started the engine, turned everything on, even, held the brake so the brake light was lit, turned the turn signal on and then set the idle to about 1,200 rpm, problem solved! With everything off, the idle was negligibly faster (it was always between 1,200 and 1,300), BUT with everything on, it did not drop under 1,200 rpm that much = no stalling.

* I don't know the exact rpm, I just assume as the first mark is 1,000 rpm and the next mark is 1,500 rpm. The manual says +/- 50 rpm or something like that.

* The charging system of my ZX7R was giving healthy 14.5v. I'm not electrician and volts and amperes and all that, nah. I was told the brushes were to be changed, but alright at the point I was fidling with it.

* I'm not sure if this was my issue, or I just completely incidentally fixed a different issue. But it worked, I did 5000 miles on the bike since then and sold it to a happy new owner who has not called me back yet, so I guess the bike runs still well enough.
____________________
'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor

[R84]

[temeluchus]

All the additives are mostly paraffin, which helps shift the water.
____________________
Some shite cruiser. Now with guns and FREEDOM!

[R84]

Thanks all. New info...decided to give it a crank when i've got home, 24 hours after the episode. No additives or anything, just a random idea. Hit starter, click. More clicks. Starts to turn, and eventually, she's back idling at 1000... idle vid: https://www.youtube.com/watch?v=IVvtSl-q-4o sounds healthy enough to me. Yesterday i was all over the throttle/choke and nothing.

Now my mind is turning back to electrics again...I'll take her out properly tomorrow and see what turns up...any more suggestions based on these developments?

[R84]

Also forgot to mention, and this was something i noticed once previously too but chose to believe I didn't see it. Just after starting now I noticed a puff of smoke coming from the headstock/side of tank area, which soon stopped. Blueish grey, didn't smell of burning plastic...

[Robby]

A lack of electricity would explain the symptoms.

If it was hard to get it going, and the process involved clicking and churning, then the battery is low.

Charge the battery, then check the voltage with the bike running at around 4000rpm. Multimeter set to volts across the battery terminals, you should expect to see around 14-14.5V. Less than 13.5 is bad, less than 12 is very bad. Most likely failure points are reg/reg, then alternator - assuming it isn't something silly like a loose wire on the battery.

[R84]

[dansp1]

choke stuck on?

[R84]

[stickybackbob]

Just throwing this out there...fuel pump relay faulty?

As others have suggested, by-pass the fuel pump by connecting the carbs direct to the petrol tap. If it idles ok for a while on this set up, check the relay, then the fuel pump.

[Major Doss]

[R84]

Thought I would update this. Got hold of a multimeter and checked the battery. 12.7v after sitting for a week. 14.7v at idle, doesn't drop much with all lights on.

It started first go again. Took it around the block, exact same situation. 0.5 miles, revs begin to fall. By the time I was home, I pulled up, waited 10sec and the revs dropped at a fairly constant speed all the way to stall.

How far can you get on whats in the carbs? When it stranded me last week it wouldn't fire for love or money. After 20 mins, it did. And again, first time today. I'm thinking (before I start thinking carbs):

- Bad/kinked fuel lines
- Fuel pump/relay
- Fuel filter
- Tank vent blocked? Forgot to check for a whoosh on opening filler cap.

Also got the puff of smoke from the headstock area too...

Still haven't got the tools to take off the tank and explore plugs, HT leads etc. I was kinda hoping the battery would be junk.

Any ideas as far as my next move? I'm trying to scale from small/cheap checks, all the way up to pulling off and cleaning the carbs as has been suggested.

[R84]

[dansp1]

did you check the choke?

[Kawasaki Jimbo]

[stickybackbob]