Help needed: sudden low power

[Astandane]

Bike: 1986 Kawasaki Z400 F2, 4 cylinder, carburetor.

Hello all,

Ok so here is my problem. My recent purchase (the above bike) has been running fine all day. I have probably done around 200 miles or so (today) (and have had it for a couple of days now). On my way back home, I stopped by the shop. As I set off all was fine, I turn a corner and as I begin to pull away I am suddenly low on power.

Opening the throttle more makes very little difference, though I did have a 'blip' where all was normal for a moment.

There is no smoke from the exhaust, no oil leaking and no strong smells. All of the lights and electrical systems appear fine.

Before this the bike started very well and warmed on the choke easily. After I limped home I let the bike settle for a minute or two and started it up again. There is still a lack of power, and is now harder to start, but will start although it now idles at much lower rev. Revving in neutral doesn't blip, stutter or whatever, but doesn't have the same power as normal.

I'm thinking blockage somewhere but do not yet know the location of the fuel filter.

Any help would be really appreciated
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Kymco Pulsar 125 Suzuki GN 125 Kawasaki ZX400 Honda CBR400RR NC23

[Walloper]

Stab in Dark.

Is there Fuel in it?

Is it Petrol or Diesel?
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W-ireless A-rtificial L-ifeform L-imited to O-bservation P-eacekeeping and E-fficient R-epair

[Astandane]

Yes plenty of fuel. Have tried with tap in both ON and RES position. No idea why there would be diesel in it.
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Kymco Pulsar 125 Suzuki GN 125 Kawasaki ZX400 Honda CBR400RR NC23

[69chris]

as it happened after you turned a corner could it have 'tugged' the wiring around the headstock and partially pulled a connector apart or disturbed the throttle cable somehow ???

[Astandane]

[Walloper]

[Astandane]

[Walloper]

Wild Crack at it now...

The fuel cap vent has become blocked (as if by magic).
It would allow normal power until the fuel used produced a vacuum in the tank and that would slow fuel supply to the engine.
____________________
W-ireless A-rtificial L-ifeform L-imited to O-bservation P-eacekeeping and E-fficient R-epair

[69chris]

[P.addy]

Do you have an "OFF" on the tap or a "PRI"

If PRI, try using that.

Alternatively, 200 miles today + 1 tank of fuel is amazing, sure you haven't refueled today.

[Astandane]

[Astandane]

[Astandane]

[doggone]

Could it be running on two cylinders because one of the coils has gone?
All my bikes 'of that vintage' did that at least once.

[Astandane]

[doggone]

That's actually what made me suggest it, they often go in and out before failing totally, whereas other problems don't intermittently go away.

[Astandane]

[Walloper]

Here's another for you.

Two Triumph Sprint STs
One less than 4k on the way home one evening I noticed a loss of power. Topped up fuel tank but still the same. The fuel supply is via an electric valve under tank.
Second bike same problem but at 6k.

Dealer check determined failed Ignition coils on two cylinders of 1st bike and one on the 2nd bike.

Low mileage failures in areas that SHOULD be bullet proof with today's tech. I no longer own British Bikes. (apart from my two Trusty Auld Beezirz)
____________________
W-ireless A-rtificial L-ifeform L-imited to O-bservation P-eacekeeping and E-fficient R-epair

[doggone]

I had one go about 4000 miles.
When they go they go.

[Astandane]

[Astandane]

[doggone]

Well don't rule coils out because it's an easy fix.
See what happens if you take the leads from one coil off.
It will either not run at all or make next to no difference.
Don't forget which one goes where.

[Astandane]

[Walloper]

[Astandane]