No Start with Spark, Compression, and Starter Fluid!

[BikerB]

Background on this bike: I got this 08 Ninja 250 cause it was abandoned and sat for at least 2 years at my complex. The engine was seized but I put some WD-40 in the spark plug holes, left for an hour and came back and cranked the crank bolt and got it loose. It now turns over just fine but won’t start.

Any ideas what the issue could be? There’s good spark with new spark plugs when I test it outside of the cylinder but it still won’t start with starter fluid directly into the throttle body (no airbox on) and the choke open. I can get it to run for a second whenever I run or ride down a hill and pop the clutch so I think there’s good compression but it dies super quick. I cleaned the carb yesterday and it has the same symptoms as it did before I cleaned it (there wasn’t much to clean though. The only thing I can think it might be is the California emissions valve on top of the engine is disconnected (got stolen off) so some vacuum leaks through the top but even when I block it with my hand I feel compression but no difference in starting. Battery is new and fully charged with battery tender. I have a new starter and starter clutch on the way but I’ll probably return them. Any help is appreciated! Thanks!

Here’s a video of me trying to start it!

https://youtube.com/shorts/06EwRLKnLh4?feature=shared

It will start for a second when I bump start it though…

https://youtube.com/shorts/MklbDzh75eo?feature=shared

[Triple Jim]

Hello Bryce, welcome!

You mentioned "throttle bodies", but I assume this is a US bike with two carburetors, correct?

Don't use starter fluid. The delicate diaphragms in the carbs can be damaged from that, and they're expensive to replace.

I'd start with a compression test. The problem could be valves that aren't sealing, maybe because of rust, or maybe because they've never been adjusted and are no longer seating.

I'll defer to @ducatiman for the question about the decel valve.

[ducatiman]

BIKERB previously posted: "I cleaned the carb yesterday and it has the same symptoms as it did before I cleaned it (there wasn’t much to clean though"

I'll submit the carb idle circuits (at minimum) still require work cleaning/clearing. Fully clearing these 250 carbs can be QUITE tricky.

[BikerB]

Originally Posted by Triple Jim

Hello Bryce, welcome!

You mentioned "throttle bodies", but I assume this is a US bike with two carburetors, correct?
.

Yes it’s the US version with 2 carburetors. So the fact that it will start for a second when I bump start it isn’t a guarantee that there is compression? I’ll get a compression tester from autozone but what should the compression be? Also you don’t think the CA emissions breather on top of the engine is causing an issue? Can I just cap it or run it straight to the air box?

[BikerB]

Originally Posted by ducatiman

BIKERB previously posted: "I cleaned the carb yesterday and it has the same symptoms as it did before I cleaned it (there wasn’t much to clean though"

I'll submit the carb idle circuits (at minimum) still require work cleaning/clearing. Fully clearing these 250 carbs can be QUITE tricky.

Any tips on making sure I clean it thoroughly? I was able to get the main jets out and used a wire to poke through. There wasn’t really anything though. I didn’t have a screw driver that fit for the idle jets but the rest of the carb was so clean I didn’t bother trying to clear them which maybe is my mistake haha

[Triple Jim]

Here's some information about the passages in the carbs: https://n4mwd.blogspot.com/2013/10/s...-passages.html

Or PM ducatiman and ask about his service. He's expert in restoring these carbs to new condition. He did mine for me a couple years ago.

He's right that the problem is likely clogged idle circuits. The compression test is worth doing anyway, because as I've said before, if your valves are out of spec, you'll be chasing carb problems forever.

[ducatiman]

assure that EVERY circuit within Triple Jims link is, in fact, totally clear.
If its above your expertise....PM me.

[BikerB]

I just went through all the circuits and cleared them. The idle jets were super clear but I think the left and right holes that come from the idle circuit and main jet circuit were blocked but I poked through with a wire and now they shoot carb cleaner! Is that where the fuel gets mixed with the air— on the air box side? I figured it would get mixed on the intake side or somewhere in the middle.

Warning I tore a diaphragm pulling it out cause I got carb cleaner on it and it was weak! Take them out first! I’m waiting for a new one to come but in the mean time I’m hoping that was the issue! I went to autozone to rent a compression tester but they didn’t have one small enough. Anyone know where I can find one? I’ll update on Monday when the new diaphragm comes!

[BikerB]

*update* while trying to perform a compression test I looked down the spark plug hole and saw the hole and piston head are super dirty. I found the bike with a spark plug pretty loose and the coil unplugged on one of the plugs. Could that be causing an issue or will it burn off later?

[Triple Jim]

I don't think a gunky piston crown is the source of your trouble.

[BikerB]

I’m at a loss. I installed the carb and I’m having the same symptoms. I cleaned every passage and poked wire through all the holes in all the jets and still nothing. The only 2 things I can think of are if the plug isn’t making hot enough spark under compression in the cylinder or if there isn’t any compression. Most likely the latter. I’m wondering if the chug chug sound I here is the gas igniting but without compression, it doesn’t do anything so it all just leaves the exhaust. Does that sound reasonable?

[Triple Jim]

A compression test will answer that.

[ducatiman]

Sorry but wire can't possibly follow every bend, kink and routes of both fuel and air passageways, no way.

[BikerB]

Finally got a compression tester. I’m getting 75psi max and it should be about 120psi so I’m thinking the piston rings got messed up if they seized to the cylinder wall and that’s why the engine was seized. Any thoughts on if it’s worth rebuilding? I got the bike for free and I’m about $400 in. I’m thinking of selling it as is for $750-$1k.

[Triple Jim]

Now you add a squirt of oil to each cylinder and repeat the compression test. If the pressure comes up, the rings are at fault. If not, the valves are not sealing. If the rings are not sealing, sometimes they will get better with a little run time.

[ducatiman]

i'd suggest using Marvel Mystery Oil for freeing up stuck piston rings