Last week I bought a 2014 Kawasaki Ninja 300 crazy cheap because the owner started having problems with it; causing it to be unrideable. He had the bike for about 1 year and everything was fine until a month ago when the bike started bogging out on him. He mentioned that it starts up perfectly but as soon as he revs it or accelerates past 2.5-3k RPM's it (tries to) dies on him unless he eases off the throttle or shifts gear.

He started tinkering with it to see what was going on and he realized the air filter had disintegrated and more than likely went into the engine. He still rode around with it under 3k RPM but the issue didn't go away so he listed it for sale.

I'm going to get to work this weekend on it to see what was going on and see if I can figure out the issue. Where do y'all recommend I start? What do you think might be going on?

Thanks!

The problem is almost certainly dirty carbs. They're not easy to clean, so don't try until you read all about the various passages, O-rings, diaphragms, etc..

In case you want to have a Pro with plenty of Ninja 250 carb experience clean and restore them to new condition, Ducatiman here on the board is your guy.

Welcome to the board, Dave!

Greetings & Salutations Dave!!! :wave:

Could be many things. Most likely some sort of vacuum-leak:

1. check rubber manifolds between throttle-body and head
2. check rubber hose between manifold and MAP sensor
3. measure MAP-sensor voltage-output with key ON/bike OFF
4. measure MAP-sensor voltage-output with key ON/bike idling
5. compare #3 and #4 with values given in manual

Most likely issue with MAP sensor, disconnected or cracked hose is common culprit for these symptoms. Might also be fuel issue:

6. how long was bike sitting before owner ran it recently? If more than 6-months, dump tank and put fresh petrol in with some PEA-based fuel-system cleaner
7. fuel pump? Follow test in manual to measure fuel-pump flow volume and pressure.
8. fuel filter? Might be implicated in #7 if flow is below limits.
9. fuel injectors clogged? There's way to measure their flow. Might be easier to just send them to https://mrinjector.us for cleaning with before& after flow-testing

10. sparks are least likely, but may be issue. Pull plugs and take look at them. Inspect spark by grounding plug onto engine and cranking. What colour is spark?

The problem is almost certainly dirty carbs. They're not easy to clean, so don't try until you read all about the various passages, O-rings, diaphragms, etc..

In case you want to have a Pro with plenty of Ninja 250 carb experience clean and restore them to new condition, Ducatiman here on the board is your guy.

Welcome to the board, Dave!

Thank you for the quick reply!

Definitely not the carbs since it's a 2014 Ninja 300; No carbs in these bikes that I'm aware of.

Greetings & Salutations Dave!!! :wave:

Could be many things. Most likely some sort of vacuum-leak:

1. check rubber manifolds between throttle-body and head
2. check rubber hose between manifold and MAP sensor
3. measure MAP-sensor voltage-output with key ON/bike OFF
4. measure MAP-sensor voltage-output with key ON/bike idling
5. compare #3 and #4 with values given in manual

Most likely issue with MAP sensor, disconnected or cracked hose is common culprit for these symptoms. Might also be fuel issue:

6. how long was bike sitting before owner ran it recently? If more than 6-months, dump tank and put fresh petrol in with some PEA-based fuel-system cleaner
7. fuel pump? Follow test in manual to measure fuel-pump flow volume and pressure.
8. fuel filter? Might be implicated in #7 if flow is below limits.
9. fuel injectors clogged? There's way to measure their flow. Might be easier to just send them to https://mrinjector.us for cleaning with before& after flow-testing
The fuel is all good. I checked all that and it all looks solid. I will put #1-5 on my to-check list though!
Thanks!

Thank you for the quick reply!

Definitely not the carbs since it's a 2014 Ninja 300; No carbs in these bikes that I'm aware of.

Sorry! I keep forgetting that the this site covers more than the 250s now.

I posted this on the Ninja 300 forum as well -

I'd start by draining the fuel, and refilling with fresh. Also get a new stock air filter. See if any parts of the damaged air filter may be stuck in the throttle bodies.

Look at the inside of the tank for debris or rust that may be restricting the flow to the fuel pump. It's possible the pump could be bad.

Check the battery voltage. Many engines do not like to run well with low voltage. Before starting, it should be 12.7V or more. During cranking, it should stay over 10V.

+1 to the above...furthermore...I'd suggest replacing injector filter baskets, ultrasonically cleaning injectors using PROPER machine. Very well could be clogged.

Got the bike started and it’s not dying anymore. Starts just fine without hesitation and stays on no problem. HOWEVER, she still doesn’t rev past 2-3k when given throttle. See link below for the video I took and let me know what you think.

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