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wr450 has possible intermittent spark? or carby issue?

By Wounded Lobster,
in WR400F/426F/450F

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Wounded Lobster

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Hey guys wondering if you have any ideas on this one. Sorry for wall of text, I have a bad habit of that.

 

The bike *does* idle and it *does* ride, but at seemingly random intervals (every 5-10 seconds) it will just completely cut out as if I turned the key off, or you are running on your very last bit of fuel.

 

Actually riding it seems to make this happen faster. So could be rpm related, or load related, or vibration of movement rattling a connection?

 

If you are riding, the bike will just roll start again.

 

Initially I thought it was a carburetor issue as I have had pilot circuit problems before, but have a few reasons to believe it is electric.

A) it happened instantly and without warning, no gradual onset, and mid-ride, just like a wire came loose??

B ) I've since pulled and cleaned the carb somewhat and had the exact same issue 15m up the road.

C) Seems to happen regardless of throttle position (pinning it vs putting along)

D) I cant think of any way the bike could be getting intermittently starved of fuel or air in this manner.

 

I know that my regulator is not right, as its from a 2007 and bike is 2004 but this has been the case for a long long time and not caused issues before. If it is a connection on the regulator, would it cause the spark to fail? Could it be stator? CDI? Ignition coil?

 

I have changed the spark plug, no effect.

 

Just looking for a point in the right direction here, as i'm not even 100% sure it is an electrical issue.

 

Thanks in advance, you guys have really helped me out in the past.

 

Phil.

Edited by Wounded Lobster
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Wounded Lobster

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How long does it cut out for?

 

Seems to be pretty random but short. There is usually some sputters first, then cuts out long enough to stall. Sometimes it just turns straight off.

 

If you are idling, obviously bike is just off until you start it again.

 

At speed, there are sputters, and the cuts are short enough that if you roll start and just keep it pinned, you can keep enough speed up before the next cut that it will roll start again, and you can actually keep the bike moving this way. It's how we got it back onto tarmac from where we were on the beach. But it wasn't pretty.

 

blocked petrol tank vent

try riding without your fuel tank cap in place, or loosened off

 

Wouldn't have thought so as it happens quickly and float bowl is always full when I drain it.

Still worth a shot. I'll try it this arvo and get back to you. Thank you.

 

EDIT: I'll see if I can borrow a gopro soon, so you can hear what is happening.

Edited by Wounded Lobster
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Wounded Lobster

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blocked petrol tank vent

try riding without your fuel tank cap in place, or loosened off

 

Tried with cap off, same problem.

 

Definitely seems to be load related. revving through at idle seems mostly fine.

Problem doesn't really get bad til you let the clutch out.

I don't understand how thats possible or what it implies??? Can anyone help?

Going to pull carby again and be very thorough.

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Grand Master

still2smokin

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You should check the connector from the wiring harness to the coil/spark

plug boot for corrosion .

I chased a problem on my bike with exactly the same symptoms as you are

describing and after replacing the stator, coil and ripping the carb apart

5 times it ended up being that connector.

Tried cleaning it with no luck , had to cut it off and make a new one .

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Wounded Lobster

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Dying stator

Would that cause the intermittent problems I'm getting? I hope it's not this as it's expensive to swap. Guess it will stay on the list until i've tried the cheaper solutions. Thanks!

 

TPS? Just giving food for thought, I have no clue to be honest

Ah, you never know! I'll disconnect it next time I'm out working on it. Haha, if you are right i'll send you a homemade cookie.

 

Do you have any electrical mods on the bike to consider.  I had an issue with a DS kit that was making the electrical system die, to the point the bike wouldn't run, but just sputter and backfire.

Not realllly, nothing I would expect to interfere with ignition. Apart from the incorrect regulator (waiting on a replacement now), trailtech vapor, uhh wired my indicators to hard-active and bypassed flasher unit that refuses to work, headlight is disconnected but was connected when bike started having issues, horn gone too. These are all very minor & nothing else springs to mind. Thanks!

 

You should check the connector from the wiring harness to the coil/spark

plug boot for corrosion .

I chased a problem on my bike with exactly the same symptoms as you are

describing and after replacing the stator, coil and ripping the carb apart

5 times it ended up being that connector.

Tried cleaning it with no luck , had to cut it off and make a new one .

Hmm, that sounds promising. I actually remember seeing mine and thinking it was f*****.  What did you do about a new connector? The factory one slots nicely into the little rubber boot to keep crap out of there. If cleaning out the carb has no effect (thinking it could well be gunk i missed that is intermittently sucked onto main jet/circuit), this will be the next option. I might even do it if the bike is fixed anyway. Thanks!

Edited by Wounded Lobster
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Grand Master

still2smokin

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Posted

Would that cause the intermittent problems I'm getting? I hope it's not this as it's expensive to swap. Guess it will stay on the list until i've tried the cheaper solutions. Thanks!

 

Ah, you never know! I'll disconnect it next time I'm out working on it. Haha, if you are right i'll send you a homemade cookie.

 

Not realllly, nothing I would expect to interfere with ignition. Apart from the incorrect regulator (waiting on a replacement now), trailtech vapor, uhh wired my indicators to hard-active and bypassed flasher unit that refuses to work, headlight is disconnected but was connected when bike started having issues, horn gone too. These are all very minor & nothing else springs to mind. Thanks!

 

Hmm, that sounds promising. I actually remember seeing mine and thinking it was f*****.  What did you do about a new connector? The factory one slots nicely into the little rubber boot to keep crap out of there. If cleaning out the carb has no effect (thinking it could well be gunk i missed that is intermittently sucked onto main jet/circuit), this will be the next option. I might even do it if the bike is fixed anyway. Thanks!

 

I cut it off and made a temp one with female spade connectors to prove that was the problem .....

 

IMG3056_zps1887e792.jpg

 

IMG2357.jpg

 

(The PO had put a lot a of die-electric grease in there)

 

permanent fix was a new wiring harness .

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Wounded Lobster

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I have an update.

Today I pulled the carb and cleaned it out really well.

It started up immediately and idled perfectly without a blip for maybe 20 minutes.

Then I took her out for a spin, and it was like a new bike.

But it ran for maybe 2 minutes and then just turned off. Tried roll start, got nothing.

There was no sputtering this time, just off. And would not start again with electric or kick.

 

still2smokin, I had a look at my ignition harness - this is what it looks like.

http://i.imgur.com/fWBQfQz.jpg(sorry for pic quality)

Looks ok, i think, so I haven't yet tried the spade connectors.

 

I have an idea but im not sure?

So bike will not start but I assume fuel & air is OK as carb is clean, therefore we have no spark (yet to double check).

However my vapor shows rpm when trying to start, meaning I have voltage at the coil harness. (But im not sure if it means the voltage is high enough?)

The only thing between that voltage and the plug is the ignition coil.

Its not the plug.

It must be the coil?

Edited by Wounded Lobster
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Wounded Lobster

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Close the plug gap down to about 0.25mm

This lessens the voltage required to fire the plug - it is a trick commonly used to detect failing HT coil

 

I am going to try this.

 

So I assume,

If I have no spark on regular plug, and no spark on closed gap plug, but voltage at coil harness, coil is at fault?

But if I have no spark on regular plug, and have spark on closed gap plug, its just incorrect voltage to coil? Or that the coil doesn't step up voltage enough????

Edited by Wounded Lobster
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Wounded Lobster

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So I hate to be 'that guy' but i was in the process of trying your suggestion, graham.

 

And then I found this.

http://i.imgur.com/ymYE6Qf.jpg

 

You think I would've spotted this by now.

But Im a f*#$& idiot.

 

Thanks for all the help guys and sorry about me being a f*#$& idiot.

Im such a f*$%* idiot.

Edited by Wounded Lobster
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