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gregnextdoor

Need advice about my 426 PLEASE!

41 posts in this topic

I bought this 426 last year for $1400 cash. At that time, it ran pretty great. I was riding it medium hard in 5th gear and it quit on me very much like a solid killswitch, and hasn't fired since. Took the stator cover off and theres alot of oil in there, I know it needs a full rebuild.. Dealership says it'll be about $2grand, and obviously my concern is how to get around that high of a price to get this thing back in tip-top shape. Can someone kindly list my options as far as low cost mechanics? Or salvage bikes (even other than a 426)? Any suggestions? Everything else about this bike is flawless perfect, not a bushing is worn out, it's never been ran hard, and it has never had any kind of real maintenance. It's in too good of shape to junk..

 

 

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I'm pretty sure it has a wet stator, so having oil in there isn't a problem I don't think. 

 

How do you know it needs a full rebuild?

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You are guessing

 

You must pull it apart  to determine the issue, or pay someone else.

 

Get a service manual, read it, do the tests on compression, stator, valve clearance, etc, and see what you have .

 

Never ever ever ever take your motorcycle to a Dealer.

 

They do not have trained mechanics for troubleshooting or a staff that cares.....unless....they are sponsering racers, then they will have real mechanics.

 

Goolge 'motorcycles + your zipcode" and start researching on where the 'real' motorcycle mechanics are......

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This is not me guessing, that's what they told me at the Yamaha dealership. I took my bike there because I thought they would do the best work. They barely charged me anything to evaulate, but they did determine that there are seals blown down in the bottom of my engine and that it will take the most extensive of repair jobs to fix.
I want the work to be done right, by someone who really knows 426's and other high compression 4 stroke dirt bikes.. Not some guy on craigslist who can get lawnmowers running again.

It seems to me, dealerships, charging $85+ per hour, WOULD have knowledgable troubleshoot staff, and REAL motorcycle mechanics. I'm just paying the dealership for the repairs as well as the mechanic which is a huge middle-man fee.

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I agree that the personnel in a Yamaha service department should be the most qualified.  It's certainly true in the automotive world that the best information on late models is available at the dealerships.  But we have a problem here to begin with, in that there are no seals in the bottom of your engine to "blow" and cause the engine not to run.

 

The engine needs 3 things to start and run:

 

  • Compression.  There should be a distinct "hard spot" in the engine's rotation as the intake valve closes to begin the compression stroke.  The absence of this indicates a physical problem with the engine hardware, such as rings, piston, cylinder, valves, and/or timing chain.
  • Fuel: Has to get into the engine.
  • Spark at the right time.  Check for spark. If present, check to see if the flywheel shows the TDC mark when the piston is actually at TDC.

All YZF series engines run the stator in the engine oil.

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This is not me guessing, that's what they told me at the Yamaha dealership. I took my bike there because I thought they would do the best work. They barely charged me anything to evaulate, but they did determine that there are seals blown down in the bottom of my engine and that it will take the most extensive of repair jobs to fix.

I want the work to be done right, by someone who really knows 426's and other high compression 4 stroke dirt bikes.. Not some guy on craigslist who can get lawnmowers running again.

It seems to me, dealerships, charging $85+ per hour, WOULD have knowledgable troubleshoot staff, and REAL motorcycle mechanics. I'm just paying the dealership for the repairs as well as the mechanic which is a huge middle-man fee.

 

Their statements to you makes believe they are clueless, which is typcial. 

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I agree that the personnel in a Yamaha service department should be the most qualified.  It's certainly true in the automotive world that the best information on late models is available at the dealerships.  But we have a problem here to begin with, in that there are no seals in the bottom of your engine to "blow" and cause the engine not to run.

 

The engine needs 3 things to start and run:

 

  • Compression.  There should be a distinct "hard spot" in the engine's rotation as the intake valve closes to begin the compression stroke.  The absence of this indicates a physical problem with the engine hardware, such as rings, piston, cylinder, valves, and/or timing chain.
  • Fuel: Has to get into the engine.
  • Spark at the right time.  Check for spark. If present, check to see if the flywheel shows the TDC mark when the piston is actually at TDC.

All YZF series engines run the stator in the engine oil.

 

If there is supposed to be oil in there, they are either:

1. full of shit, don't know anything.

or

2. full of shit, giving me the runaround.

 

This would bring me hope, maybe it won't be such a horrible issue.. I'll just have to get someone else to look at it.

 

 

I did verify it is getting spark. And I am sure it's getting fuel as far as the carb, cannot attest for the jets or anything else, though I did have the carb off and cleaned it best I could..

 

What the real problem is, like you described, it lacks that dead stop at the top of the compression stroke. I have gotten very comfortable with how the decompression lever works and how to get it started hot or cold. But the moment it quit on me, it hasn't had that stop any more, just keeps kicking over and over. I can tell the decompression valve is actuating properly, and can hear a difference with it pulled or not, while kicking it.

 

You suggest that would be rings, piston, cylinder, valves, and/or timing chain. All of this is beyond me, and I really want it to be fixed factory-proper. Maybe even tuned for longevity over performance, if that's a possibility. What should I do?

And would that not mean the most extensive of repair jobs?

Edited by gregnextdoor

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You have an old motor with probably lots of hours on it.

They need maintence before failure occurs.

It sounds like this was not done.

 

If you love the bike, rebuild it and keep it.

 

There is no way to know what is wrong until you open it up.

It could be a bent valve, a slipped timing chain, a cracked piston, etc etc.

 

Again, I would find a local professional racing mechanic, and pay him to diagnose and/or repair, since this is by your own admission, beyond you.

 

 

 

Otherwise, sell it as is.

Edited by Kah Ran Nee

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 There SHOULD be oil in the stator, that is how these engines are designed.

 

 Before you tear it down make certain the decompression lever, cable, and actuation lever down on the motor are all operational and working/adjusted  correctly.

 

 On my 1999 if the decompression lever on the handlebar is rotated up, even a little bit, it can tighten up the cable to where it actuates the decompression lever and will kill the bike, or prevent it from starting. This is real noticeable as it does not stop the motor when rolling it over to top dead center.

 

Both the YZ and WR's are pretty bullet proof and very reliable in most instances, unless severely abused or not maintained. Why do you say you know it needs a rebuild? Did it smoke, miss, not have power?

 

 You say it was running fine and just quit. Did it make any BAD noises, like a crunching  or other awful noise, or just stop running and you coasted to a stop?

Edited by ThumpMe

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If you can kick through the stroke without the compression lever pulled, you need to look at the valves and head.  When new, I could almost stand on the kickstart lever and it would only very slowly leak down.  My bike started and ran for a while even after I could kick through the stroke with mild difficulty.  As it turned out, after 15000 miles of singletrack, I had worn the back side of the valve so it didn't seal against the head.  You need to pull things apart, take pictures and report back.

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 There SHOULD be oil in the stator, that is how these engines are designed.

 

 Before you tear it down make certain the decompression lever, cable, and actuation lever down on the motor are all operational and working/adjusted  correctly.

 

 On my 1999 if the decompression lever on the handlebar is rotated up, even a little bit, it can tighten up the cable to where it actuates the decompression lever and will kill the bike, or prevent it from starting. This is real noticeable as it does not stop the motor when rolling it over to top dead center.

 

Both the YZ and WR's are pretty bullet proof and very reliable in most instances, unless severely abused or not maintained. Why do you say you know it needs a rebuild? Did it smoke, miss, not have power?

 

 You say it was running fine and just quit. Did it make any BAD noises, like a crunching  or other awful noise, or just stop running and you coasted to a stop?

 

Thanks for replying, good info.

 

I know just what you mean about the decompression lever, I adjusted it all to my preference when I first got the bike. I am 99.9% sure the cable is in good order and not binding, and that it is actuating the valve correctly. It goes back in place so smooth, I can do it fast like just drop it like the clutch and hear a tiny click down there when it hits closed position..

The most notable concern is that there is no dead stop at the top of the kick anymore, decompression lever pulled or not, same amount of compression over and over. It sounds a little more throaty with the lever pulled. Also, I can really smell it when I turn the petcock to on and start kicking it over, that gasoline smell with a hint of dirty carb, so I'm gonna guess that the jets aren't fully stopped up. In the tank is brand new highest grade pump gas.

 

When I did ride it, it wasn't quite perfect, seemed to bog down sometimes, at low rpms, kind of just a dirty carb feel, nothing really of note just needed a tune up from sitting around. So no BAD noises or smoke, and the power was SO there, when I opened it up. Never heard crunching or explosions or metal shavings inside my cylinder lol..

 

My last ride: Going down state maintained paved double yellow line road, mildly, 5th gear but only about half of what it can go, just cruising, then a simple solid KILL SWITCH, as if I were pushing the stop button myself...

Yes, I then coasted to a stop at what happened to be a buddy's house...

 

 Could it be blown out rings? Timing chain jumped? I think my hardware is intact, what say you?

 

 

 

PS. I have not put my mind to the deep mechanics of motorcycles/atv's, but I can ride with the best!

 

 

ALSO: I called the Yamaha dealership service dept. and told them the mis-diagnosed my bike, they are "looking into their records" and gonna call me back. Will update later.

Thanks guys!

Edited by gregnextdoor

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I'd avoid that dealer at all costs. Almost every modern bike runs oil in the stator side. If they didn't know that about that bike then they don't have the proper knowledge to rebuild it for what they charge.

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If you can kick through the stroke without the compression lever pulled, you need to look at the valves and head.  When new, I could almost stand on the kickstart lever and it would only very slowly leak down.  My bike started and ran for a while even after I could kick through the stroke with mild difficulty.  As it turned out, after 15000 miles of singletrack, I had worn the back side of the valve so it didn't seal against the head.  You need to pull things apart, take pictures and report back.

 

I honestly might just do that, but aside from having a few other projects going on, and work, I have yet to hear back from the dealership in regards to my new information. If they'll take it back in and give me a full diagnosis for another few bucks, I'll be very happy. I will also have a solid point from which to logically proceed.

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To illustrate how long these bikes can run with worn valves/head.  I prepped my bike on a Friday night, including starting the bike and riding it around the neighborhood for 5 minutes.  I loaded the bike and 14 hours later, the bike wouldn't start at all.  Complete waste of a Saturday, especially when it was a 3.5 hour drive each way...

 

Just linked these guys in another post.  For valves and head work I was impressed by Millennium Technologies http://www.mt-llc.com/

Edited by Pooley

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If it is not hitting a good solid compression stroke as you kick it through, and the decompression lever/cable is not the culprit I would then start thinking about it possibly being a valve issue.

Also as others have already stated, I would NOT EVER go back to that shop if they are not even aware of the basics on a Yamaha motor. After all they have been pretty much the same for almost twenty years now. That is enough to scare me away from them anyway.

Edited by ThumpMe

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Well the dealership finally called me back... He says that he went through his notes on the ticket, and asked the tech who opened it up to recall from memory... The following was not written down anywhere but the tech says "there was metal shavings in the oil under the stator cover" and that they suspect that's the crankshaft bearings, and it requires a full rebuild including cylinder bore over... This is the first time I've heard about this (I feel that it's pretty vital information...)

 

I'm going out here in a few minutes to open the left side of the motor myself and just have a look and I'll post my findings.

 

 

Thanks guys! I wish I were posting about something more fun.. ride pictures, go pro footage, passenger footpeg fab, not this stuff!

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How much does everyone want to bet the problem is something really simple?.......KaRahNee??

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Of course you can spend a few hours of your time and apply some common sense (Free)

Or you can pay a stealer and he should be able to apply the same common sense

Question is do you trust the stealer, 90% of them are kind of crooks

I'd be really cautious and ask alot of questions if you took it to a stealer

 

BTW: These are dirt bikes and not F1 race cars. Alot of people can fix them.......Hell, We do !!

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Ok I just went out and pulled off the left side cover from the bottom of my motor. All I found was fairly clear oil, no metal shavings whatsoever.

If you ask me, I'd say it's pretty clean inside there, besides some dirtier oil around the very bottom, not gritty.

 

What does this look like to you guys? Should I also take off the stator or something in here? Is Beechmont Motorsports in Cincinatti a joke? What should I do next? Am I an idiot? Don't answer that last one.

 

 

 

 

 

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Edited by gregnextdoor

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