keeps cutting out

[new boy]

hi just bought a yamaha fzr 400 and its been stood for 3 years and it starts fine and runs on 4 cylinders revs well but when you try and ride it it just cuts out and when i start it again it only runs on 2 cylinders and before it was parked up it was fine any explination would be great i have changed the spark plugs and leads
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I need help

[new boy]

do they have a side stand switch if so could this be the problem
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I need help

[stinkwheel]

If it has been stood for that long, any fuel that was in the tank will have gone stale. It is also possible that any that was left in the carbs may have turned into gummy stuff that would have blocked up some of the carb jets.

If I was putting a bike back on the road after sitting for three years, I would be draining any fuel out of the tank and replacing it with fresh stuff and carrying out a full service (change oil and filter, clean fuel filter, replace plugs, check air filter, check tappets).

If this still doesn't help, it may be you need to clean out the carbs, it is entirely possible that they are full of detritus.

Another thing that could cause that problem is a blocked tank breather, try running it with the tank cap open.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[new boy]

tried most of it except tappets today and changed fuel when i first started it and still no difference its as sweet as a nut just sitting running and as soon as i put the engine under any strain at all eg pulling away it stops then i start it it starts on 2 cylinders then if you leave it for about an hour its fine again it feels like an electrical problem but what do i know im a car mechanic
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I need help

[stinkwheel]

Always the same two cylinders it is dropping?

If so, try swapping over the coils, if the problem moves to the other two, you found the cause.

Battery in good nick?
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[new boy]

cheers will try that as soon as i am allowed to tinker the girlfriend doesnt like that im giving the bike more attention than her
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I need help