AT Not running right

[bazza]

Hi all im back again with another problem.

While riding at about 3k revs and below the bike seems to miss a bit as if its not getting the right amout of fuel.
But at higher revs it rides fine.
Could this be the fuel pump.
THANKS PEEPS

[YEN_POWELL]

Could be a very very sticky choke, this has no effect at high revs but when warm the bike runs badly at lower revs. Check the two easiest to remove sparkplugs to see if they are sooty.

[GSPD750]

Hi all im back again with another problem.

While riding at about 3k revs and below the bike seems to miss a bit as if its not getting the right amout of fuel.
But at higher revs it rides fine.
Could this be the fuel pump.
THANKS PEEPS

Year/model and miles? Original fuel pump?

[Steve C]

The AT has less low down grunt than might be expected for a 750 twin

On my AT (25,000 miles, reg'd in early 01) I find that when trundling along it can become a bit hit and miss at revs much below 3.5k and it's best to change down. Not necessarily a fuel problem just that the engine is running out of puff and closing in on its stalling speed. Running the bike like that tends to make it less predictable and it can cough and splutter if I tweak the throttle and engine braking is less available too.

[icenian]

I'd suspect the choke, and like Yen says it's easy to check as the plugs will be black and sooty.

An AT ought to be OK down to about 2500rpm in the lower gears, though. It doesn't make much power but should be OK if trundling in traffic in 2nd gear, for example. If it won't do that I'd suspect a choke problem that isn't too bad yet. I think I had my AT for a whole year with a dodgy-but-not-too-bad choke before it became so bad I realised something was wrong and fixed it; I then spent another 2 years of it being a bit ropey on and off; then I disabled the choke and since then it's been smooth and sweet running ever since!

Another thing that can happen at this time of year is carb icing. This affects running at low revs. It will usually appear after a few minutes at higher speeds, if you slow down and lets the revs drop. Revving the engine to keep it running works briefly (it;'ll get you to the hard shoulder, say) but the problem will affects the bike at progressively higher revs until it won't run at all. Stop the engine and after a few minutes it runs fine, as the engine heat thaws the carbs. It'll probably disappear with better weather (damp weather just above freezing seems to be the worst for it) and/or a tankful of better quality fuel. If it's really bad, Silkolene "Pro FST" sorts it completely.

[Chad]

hmm sounds like the choke to me as others have saidits not behaving like a fuel pump problem

[loftyjohn]

Hi
Check out your battery?
I had the occasional miss at low revs a couple of days latter I had a dead battery!

[Hosay]

Bazza, mine (02 plate, 25k) has a similar problem.....holding it at about 75 mph in fifth it feels like it's slightly starving of fuel but open the throttle and it pulls clear.....

battery connections are fine, no cack on the plugs so my next job is to try a new fuel pump...

Jim.

[blacksoe]

Hi all im back again with another problem.

While riding at about 3k revs and below the bike seems to miss a bit as if its not getting the right amout of fuel.
But at higher revs it rides fine.
Could this be the fuel pump.
THANKS PEEPS

start at begining set tappets check plugs balance carbs somewhere in that order

[chronyx]

I disabled the choke and since then it's been smooth and sweet running ever since!

Has it ever refused to start in the properly cold weather you guys get up there?