Sudden noise change, loss of power. [VIDEO]

[Calix]

FIXED
Spark plug came loose

Alright guys, so recently I fixed my bike up tip top and it was running fine, maybe running rich, but not giving me any other issues after I replaced the R/R which was causing the battery to die after multiple startups.

Now I have my newest problem.

Yesterday I decided to go grab some gas and run some errands. So I make the 3 mile drive to my grocery store, pick some items up, start the bike back up and begin cruising to the other side of the parking lot to the gas station.

I was in first gear doing about 6mph (about 5k) when I approach the longer "Stretch" portion of the parking lot that leads to the gas station so I went to let it wind up before I shifted into 2nd (about 8k) and I was immediately greeted by an absolutely hideous new exhaust noise and a quite noticeable loss of power even in 1st.

The sound from the exhaust is really hard to explain, though "Farting" comes to mind . So I immediately killed the engine and coasted into the gas station and filled her up. Then rolled her back into the grocery store parking lot. Pulled off the side panels to check and see if any tubes / hoses had come undone. I would explain the noise but thats what the video is for. So I had to go home and change clothes to get to work at this point and since I didnt have any rides, a had to limp the bike back home. So I drove it back home at about 30mph in 6th gear..throttle pinned. It wouldn't accelerate past 35mph no matter the gear... So I get back home put her in the garage..

Fast-forward to today, I have only checked the coolant since I read that someone with a similar story said his coolant had turned brown. My coolant is still a nice green, but with some weird whitish particulates floating around. Though it could just be random crap from the reservoir (it isnt the cleanest).

My next step is to take the gas tank off and check the plugs. Though the problem with this being the fact that the left side of my tank has a hole straight through the tank (either mechanic or PO put to big of a bolt.) I had fixed this with some epoxy though, just I now have to drain the tank using a hand pump before I remove the bolt. BUT the hoses for that hand pump are nowhere to be found so Im going to have to find some other way to siphon the gas before I can remove the tank.

https://youtu.be/hRJEFh7eZP0

Link to original page on YouTube.

[rojoracing53]

you video doesn't work for starters. My scooter once lost nearly all its power during my commute and I had to limp it in the last 4 miles WOT going like 20mph. Bike was sputtering and backfiring like crazy. Ended up being the spark plug got a little loose and was making intermittent contact.

[Calix]

Originally Posted by rojoracing53

you video doesn't work for starters. My scooter once lost nearly all its power during my commute and I had to limp it in the last 4 miles WOT going like 20mph. Bike was sputtering and backfiring like crazy. Ended up being the spark plug got a little loose and was making intermittent contact.

yea just noticed lol

Fixed, the youtube player doesnt like the video for some reason

[Calix]

FIXED!

Turns out the spark plug in the right cylinder popped out completely. Have no clue how, must of been loosening over time. Tightened the left and right plugs back down and soldered and sealed the coils to the boots.

[rojoracing53]

well that was unexpectedly easy to diagnose

[Ghostt]

Did you renew the HT leads, and disassemble the caps?

Make sure you disassemble the caps, and clean them, and yes the caps get cruddy.

Here my write-up,

Short explanation: The inside of the hard plastic caps accumulate crud the can short out the spark. This can cause rough running or failure to start. Every time you do any work on the bike: remove them disassemble and clean them and renew the wires or at least the connections.

The long Explanation, Warning engineering information can cause Drowsiness.
The ancient cylinder design of the engine dictates that the spark emanate form the center of the combustion chamber. In order to get it there, the plugs had to be located down deep in a well between the cams. This well is a perfect place for dirt and moisture to accumulate. Then because there is no cooling water at this point the metal around the plug runs very hot. Surround this with the large amount of cool metal and you have a recipe for condensation. Now K did drill a drain hole between the fins to help (a little) but it often gets plugged up.

The moisture boils off the base of the plug and the vapor condenses on the cool plastic cap and the plug insulator. This moisture forms a easier path for the electrons to ground than jumping the gap at the plug to make a spark. Misfire.
This issue is right up there with Pilot jets as a cause of trouble.

Here's some pictures that might be helpful. I took these when I replaced the wires themselves, as it was a good time for a write-up, and the wires were OEM from 1998.

IMPORTANT NOTICE: make sure to use a proper screwdriver, make sure it fits, as the parts are made of brass inside the spark plug caps


Wires are just 7mm copper core, with clear silicone jacket

[Calix]

Originally Posted by Ghostt

Did you renew the HT leads, and disassemble the caps?

Make sure you disassemble the caps, and clean them, and yes the caps get cruddy.

Here my write-up,




Here's some pictures that might be helpful. I took these when I replaced the wires themselves, as it was a good time for a write-up, and the wires were OEM from 1998.

IMPORTANT NOTICE: make sure to use a proper screwdriver, make sure it fits, as the parts are made of brass inside the spark plug caps


Wires are just 7mm copper core, with clear silicone jacket

I have read your thread on the topic previously and I have to say I was debating about going all out and rewiring everything myself. But I was a tad short on time so I settled with cleaning the caps and cylinders. I also went ahead and fixed the little rubber heads on the caps so they no longer move about.

The next time my gas tank is off, for whatever reason, I plan on replacing the wire.

[Ghostt]

Originally Posted by Calix

I have read your thread on the topic previously and I have to say I was debating about going all out and rewiring everything myself. But I was a tad short on time so I settled with cleaning the caps and cylinders. I also went ahead and fixed the little rubber heads on the caps so they no longer move about.

The next time my gas tank is off, for whatever reason, I plan on replacing the wire.

You can reused the HT leads , I just replaced mine because I had the new HT leads already.

You just have to trim enough off so the ends are fresh, it only takes a few minutes.

Renewing the HT Leads is highly recommended, if not mandatory.

[Ghostt]

If you have a some $$, I also suggest doing the CoPs modification, as it has its advantages, like a better spark for one.

https://www.ninjette.org/forums/blog.php?b=8379

https://www.ninjette.org/forums/showthread.php?t=241339

[greg737]

You'd be surprised how common this is, over the 9 years I've owned an EX250 I've read probably 15 posts where peoples' bikes have coughed out a spark plug.

Sometimes the threads in the cylinder head go out with the plug. I guess that's a sign of weakened threads from overtightened plugs.

Sometimes the threads in the cylinder head are undamaged. I guess that's a sign that somebody didn't tighten the plug properly.

You should inspect the bottom of the fuel tank. About half of the owners who posted about a blown out plug mentioned a pretty good dent in the bottom of the fuel tank.

[Calix]

Originally Posted by greg737

You'd be surprised how common this is, over the 9 years I've owned an EX250 I've read probably 15 posts where peoples' bikes have coughed out a spark plug.

Sometimes the threads in the cylinder head go out with the plug. I guess that's a sign of weakened threads from overtightened plugs.

Sometimes the threads in the cylinder head are undamaged. I guess that's a sign that somebody didn't tighten the plug properly.

You should inspect the bottom of the fuel tank. About half of the owners who posted about a blown out plug mentioned a pretty good dent in the bottom of the fuel tank.

Checked the bottom of the fuel tank. No dent Im pretty sure it was user error. I was having trouble retrieving my spark plug ratchet after properly tightening it down. So it was a tad loose, new ratchet doesnt have those problems.