How good are your diagnosis skills?

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Kevlarr

Kevlarr

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Jul 22, 2009
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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? laff

YouTube - Road Trouble.wmv


Soooooo, what was wrong? :D
 
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scotto-

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
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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-

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
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Ridin' inSane Diego, CA.
...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

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
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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

2door

Moderator
Staff member
Sep 15, 2008
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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
 
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Kevlarr

Kevlarr

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Jul 22, 2009
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One time. Never happened before and I just put 33 trouble free miles on it tonight. :D

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-

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,505
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38
Ridin' inSane Diego, CA.
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 gaslaff:-||dance1

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

Kevlarr

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Jul 22, 2009
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scotto- said:
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 gaslaff:-||dance1

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

Dan

Staff
May 25, 2008
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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

Kevlarr

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Jul 22, 2009
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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. :p
 
GearNut

GearNut

Active Member
Aug 19, 2009
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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.
 
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