How good are your diagnosis skills?

[Kevlarr]

Went out for a ride tonight and about 5 miles in the engine just all of the sudden started running poorly. I had almost no power, had to pedal assist up hills and it wouldn't idle. It almost had a pinging/knock from the engine.Tried closing the choke a bit thinking it might have somehow sucked something into the jet and be running lean but no dice. Limped it the 5 miles home, tinkered with it for about 15 minutes and had it running great again.

While I was riding home I remembered my phone has a nice camera in it so I shout some before and after video, If you listen closely you can hear the pinging I'm talking about.

Oh and in the after video, for all of you that say you can't get proof of how fast you're going, who says you can't ride WOT and hold a camera/phone to shoot video?

YouTube - Road Trouble.wmv


Soooooo, what was wrong?

 

[scotto-]

I think they are pretty good in that I can always find out what's wrong with something and 99.9% of the time I can fix it also. I'm certainly not the best but, who is?

Now time to watch yer video....cheers!

 

[scotto-]

...well the audio in the before video was not nearly as clear as the after, thus I could detect no knocking or pinging. If I were to guess, I'm thinking a loose sparkplug or the sparkplug connection may be loose or crumbling. Or there's the carb, but you said no jet blockage...clogged petcock fuel filter?

 

[Bikeguy Joe]

I hear I am pretty good at long distance diagnostics....but, I can't get you tube videos to come in on my steam powered computer, so I can't play this particular guessing game. I will "stay tuned" however.

 

[2door]

I think the engine is fine...its the speedometer that's giving you problems

Kev, is the problem consistent or was this a one time event?

Tom

 

[Kevlarr]

One time. Never happened before and I just put 33 trouble free miles on it tonight.

It was an easy fix but I doubt anyone will ever guess what it was because when I found the problem it kinda blew me away and I still can't figure out how it happened.

 

[scotto-]

It really sounds like you ran out of gas....filler up? You get that detonation sound as your engine leans out while it's starving for gas. On a 2-stroke it's a seizure theoretically when you run out of gas

Oh no.....it's got to be simpler than this.....sorry!

 

[Kevlarr]

It really sounds like you ran out of gas....filler up? You get that detonation sound as your engine leans out while it's starving for gas. On a 2-stroke it's a seizure theoretically when you run out of gas

Oh no.....it's got to be simpler than this.....sorry!

Actually that was my first thought so I stopped and dumped in my reserve bottle. Ran no different after.

So it definitely wasn't running lean.

 

[scotto-]

A maple leaf got sucked into the air cleaner? Or maybe a swarm of bee's???

 

[Dan]

I was gonna say dirty filter/fuel starvation but am gonna go with lose ignition wire. That's my final answer Alex. Or some where in the spark section. OK, that's my final answer. or....

Cool thought for a thread, Kev. Think we should do this often. Hone skills to help new folks. I am really terrible at reading a problem and helping some one figure it out.

And is kinda fun. Will there be cash and valuable prizes?

"I think the engine is fine...its the speedometer that's giving you problems" LOL Tom

 

[Kevlarr]

No maple leaves and no bees. lol

No loose ignition wire Dan.

I was kind of disappointed that the camera didn't pick up the pinging sound more. It was a sound that made me think I had a rod coming loose and it made me closely examine the head gasket. But I think it was detonation in the expansion chamber.

There's your second clue.

 

[Dan]

Doh!


For correct answer "The clap"

 

[scotto-]

Yeah, it does sound like a BAD ground....an easy fix! I've had that happen....on lots of different types of vehicles.

 

[Bikeguy Joe]

Pinging? Loose motor mounts.

 

[Bikeguy Joe]

Oh shoot, I give up....I am terrible at guessing games.

 

[Dave31]

Wrist Pin?

 

[scotto-]

Piston slap? Low octane gasoline?

Or maybe the magneto or stator came loose, changing the timing?

 

[GearNut]

Exhaust came loose at cylinder or the exhaust gasket blew out?

Edit: I should have said intake to cylinder as that is more than likely the culprit.

 

[2door]

Maybe you were running out of gas...only the other moderators will appreciate that
Tom

 

[Dan]

Maybe you were running out of gas...only the other moderators will appreciate that
Tom

Would that make it moderately appreciable? snicker, snicker