Engine dies under power

[Gil1696]

Hi all
got a problem with my 94 600m. Here goes.

Bike starts,idles and revs OK with no load.
Engine revs die off under load.
I really have to let the clutch out slowly and maintain high revs to get going.
Once going, there's no surge at all, just a deep throaty noise from the carbs whenever i twist the throttle.
Engine is very jerky, jumpy and backfires under throttle + load


I've just drained the fuel system coz I found water in the tank, filter and floatbowls. (Not touched the vacuum pump)

Any Ideas fellers??

[Northman1]

Could be the sparks dieing under load.

Check your plugs are giving a big fat blue spark, and are not looking wet or sooty.

[stef]

they are fairly straight forward engine, so the usual:
fuel (you have started on that)
and spark (already mentioned)..
work you way through those two, and you will probably find the problem
if the bike hasnt been runing for a while, it may just need a good runing in.
my pops for about 10-15 miles after a winter of very little use.

[MikeG]

As mentioned, plugs - condition, gap and are they tight? Yes really!!
Plug leads and plug caps also need a look.
Air filter??

[Shandy]

The trumpets on the top of the air box, are the facing forward as they sould be?, mine move from time to time to face the inner wall of the tank and restrict air flow.

Is it firing on both cylinders? I'm not taking the xxxx, a wire fell off on mine and it was only firing on one which made it perform like you described.

Good luck.

[MikeG]

Is it firing on both cylinders? I'm not taking the xxxx, a wire fell off on mine and it was only firing on one which made it perform like you described.

Good luck.

I suffered a short on the rear cylinder that only became obvious under acceleration, though when it rained it was easy to spot! In a misguided attempt at fault finding I took off a glove at traffic lights and grabbed the lead, the resulting yelp proved there was a poor connection.

[Shandy]

:eek: Ouch! :eek:

[nik_the_brief]

The trumpets on the top of the air box, are the facing forward as they sould be?, mine move from time to time to face the inner wall of the tank and restrict air flow.

Is it firing on both cylinders? I'm not taking the xxxx, a wire fell off on mine and it was only firing on one which made it perform like you described.

Good luck.

Yep, similar symptoms to mine the year before last, it turned out to be one of the pick up coils had packed up hence no spark to one cylinder.

[m600ben]

check you re not bending the fuel pipe under the tank when you close it, that will restrict the fuel when its needed most! (partcularly with a few pounds perched on the seat)