Ninja acceleration/fuel issue

[monkeyking118]

About a fortnight ago, after a ride around, i noticed that my ninja was behaving weirdly if i was having to keep at about 40mph. It would lose power for short periods of time if I had to roll off the throttle and pick up in a patchy fashion once I applied more throttle.

Thinking my throttle cable was dodgy, I took the twist grip apart and found the return cable had come out of the guide rails. After putting it all back together the bike was fine for a while, but after riding for about an hour today a similar problem has happened.

This time though if i roll of the throttle and then keep it in the same position the bike acts as if it is running out of fuel and becomes boggy. Any throttle action makes it splutter then suddenly roar back into life, making for an exciting but difficult to control ride.

Before anyone asks: its not running low on fuel, filled up about 20 mins before this began to happen.

wondering if anyone could help me by narrowing down what it could be.
As a general pointer, the bike appears to have been fairly neglected before i bought it. Still had the factory battery after a good 10 years and most bolts have now been replaced as many were rusted, so guessing things like spark plugs and air filter have been left too.
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Baimo RSR125(sold), Suzuki En-125 '06 (sold), Honda VFR400 NC-30 '92(sadly stolen), Kawasaki ZX6R Ninja '96 (sadly stolen), Kawasaki GPZ500s '93 (sold), KTM rc390 '16 (f***ing stolen), Kawasaki Z750R, Triumph Daytona 675

[0l0dom0l0]

give it a decent service if you havent already. check the air filter and plugs primarily to go with the problem but if the oil and filter havent been done for a while do those as well (y).

if it doesnt get any better after that, its the usual drain carb bowls. and if thats not much better then you might have to take the carbs off and give them a decent clean.

hope that helps.

[monkeyking118]

Ok, investigating another noise that had puzzled me over the past two weeks, I found that my chain is now mysteriously and ridiculously loose. Wondered if that would contribute to the problem?

It is loose enough to hit the swing-arm if you push it to test freeplay (about 3 inches), which would explain the sharp crack i hear when i go over some speed humps and bumps. originally thought my fairing was loose.
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Baimo RSR125(sold), Suzuki En-125 '06 (sold), Honda VFR400 NC-30 '92(sadly stolen), Kawasaki ZX6R Ninja '96 (sadly stolen), Kawasaki GPZ500s '93 (sold), KTM rc390 '16 (f***ing stolen), Kawasaki Z750R, Triumph Daytona 675

[monkeyking118]

cheers for the advice, oil and filter done recently but haven't ventured down to the spark plugs yet. Figured the air filter might need changing too, will try these out on next day off.
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Baimo RSR125(sold), Suzuki En-125 '06 (sold), Honda VFR400 NC-30 '92(sadly stolen), Kawasaki ZX6R Ninja '96 (sadly stolen), Kawasaki GPZ500s '93 (sold), KTM rc390 '16 (f***ing stolen), Kawasaki Z750R, Triumph Daytona 675

[0l0dom0l0]

i wouldnt think the chain would cause the bike to bog down. but they do say you can loose silly amounts of power through a incorrectly set up chain.

if you do all the above with a bit of luck, it will sort it!

[Robby]

Drain the carbs and check for water. For whatever reason it won't behave when the slides are at a fairly constant level and it's sucking the fuel up the needle jet, but on acceleration it's ok. If it has pumped carbs then they are doing most of the work on accel. Water and general crud mixed in water is a possibility - have you been running on reserve recently?

Do the other service bits as well, sounds like the whole things a good service. The chain getting loose could be because the rear wheel spindle is loose, or it could be that a bit of use after it has been standing for ages has just finished freeing it up (or destroying the o-rings) and made it appear to stretch.

The problem you're describing could be fuel or electrical related. New plugs, a charged battery, and drained carbs gives you a good starting point for diagnosis.

[monkeyking118]

I'll get on the service as soon as poss, should have done it by now anyway but work gets in the way!
Hoping its a fairly simple fix, bought the bike in a hurry after the nc30 went missing and its pretty much eating my cash at the mo. Just little things that wouldn't be an issue if checked regularly.

The chain is a puzzle as it was fine before the MOT a few weeks ago and the bike has been in daily use over the last four months.
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Baimo RSR125(sold), Suzuki En-125 '06 (sold), Honda VFR400 NC-30 '92(sadly stolen), Kawasaki ZX6R Ninja '96 (sadly stolen), Kawasaki GPZ500s '93 (sold), KTM rc390 '16 (f***ing stolen), Kawasaki Z750R, Triumph Daytona 675

[monkeyking118]

Ok, finally got the spark plugs and air filter changed, this is what I found when I replaced them.

Bike certainly sounds a lot better already.
____________________
Baimo RSR125(sold), Suzuki En-125 '06 (sold), Honda VFR400 NC-30 '92(sadly stolen), Kawasaki ZX6R Ninja '96 (sadly stolen), Kawasaki GPZ500s '93 (sold), KTM rc390 '16 (f***ing stolen), Kawasaki Z750R, Triumph Daytona 675

[0l0dom0l0]

that isnt going to be helping is it .