Bent crank?

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sixbennetts
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Re: Bent crank?

Post by sixbennetts » Thu Nov 07, 2019 8:43 pm

Wow, this is very helpful, Snakeoil! Yes, no hydrolock involved, so maybe it isn't the crank! I'll discuss it with Becky's boyfriend this weekend, and we'll start with the starter and flywheel check. Van did say that a bent crank would cause a wobble at idle, and a progressively worse shaking with increased rpm, and that's exactly what it's doing.

Would a spun flywheel do the same, do you think?
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2007 Ural Retro, "Подарок солдата солдату"

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Re: Bent crank?

Post by Snakeoil » Fri Nov 08, 2019 9:43 am

I had a bent crank in my 650 and it was like that when I bought it. I still maintain that Ivan bent it assembling the engine with a press. Anyway, there was 0.030 runout at the nose of the crank and yet the engine did not vibrate to a point that I gave it any thought. But then again, I own vintage Brits.

If the flywheel is no longer straight on the crank, it is going to make it want to shake to some extent, I would think. Although my flywheel had over 0.070" of face runout and like I said, was not making a lot of vibes.

I really don't think anything is bent. I think you have a really bad running problem. Ignition is losing its mind would be my first guess. I think you mentioned fuel being okay. But just to be sure, did you drain the tank and put new fuel in? I'm thinking that the little turds might have peed in your tank or poured a beer into it. I'd drain the tank, lines, float bowls if you have not done that already. And again, excuse me if you already told us this. I'm headed out the door and just wanted to reply.
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sixbennetts
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Re: Bent crank?

Post by sixbennetts » Fri Nov 08, 2019 2:35 pm

All that is on the list, buddy. Thanks. I'll update as we diagnose and repair.
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I love her, she loves me.
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2007 Ural Retro, "Подарок солдата солдату"

"I'm slow and like to go old."
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Re: Bent crank?

Post by Mr Wazzock » Fri Nov 08, 2019 6:14 pm

:lurker:
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Re: Bent crank?

Post by Snakeoil » Fri Nov 08, 2019 7:47 pm

You are about 2.5 hours north of me. If you were closer, I'd be up there. I'm really curious what is going on here. I have a sneaking suspicion this is something very basic/simple. Often the simple stuff is the hardest to figure out.
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Re: Bent crank?

Post by Claus » Sat Nov 09, 2019 9:17 am

Snakeoil wrote:
Fri Nov 08, 2019 7:47 pm
I have a sneaking suspicion this is something very basic/simple. Often the simple stuff is the hardest to figure out.
That was my first thought.
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Re: Bent crank?

Post by Mr Wazzock » Sat Nov 09, 2019 10:34 am

Image

This is an itch I gotta scratch! :D
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Re: Bent crank?

Post by sixbennetts » Sat Nov 09, 2019 4:00 pm

Tomorrow we'll try to get to it. And Snakeoil, thanks for the offer, I really do appreciate it. We'll get it figured out, I'm sure.

It bugs me because it starts and idles perfectly, just like it always has, with just a little bit of extra vibration. It's when you give it the gas incrementally, you can feel the vibration/shimmy get worse.

We'll see.
I have a funny wife. Hilarious, really.
I love her, she loves me.
______________________________________
2007 Ural Retro, "Подарок солдата солдату"

"I'm slow and like to go old."
Plattsburgh NY

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Re: Bent crank?

Post by El queso » Sat Nov 09, 2019 9:07 pm

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Re: Bent crank?

Post by cookiemech » Sun Nov 10, 2019 6:52 am

Excellent PhotoShopping of the Hardy Boys cover!!! I have at least one copy of every single Hardy Boys (original series) book. This looks like a scene from The Shore Road Mystery.
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scottmastrocinque
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Re: Bent crank?

Post by scottmastrocinque » Sun Nov 10, 2019 8:31 am

First off, I'm very sorry that criminals did this to you. It is underserved and uncalled for. I despise thieves.

More than likely, they broke lose something along the drive line, more than likely at the clutch/flywheel. The drive line is designed to apply force in one direction, from the engine to the drive shaft to the wheel. Trying to bump start the bike, especially down a hill at speed and with the skid mark you describe, the forces would have been applied the opposite direction, from the wheel to the driveshaft to the clutch plates and flywheel. I have seen a few BMW flat twins damaged from hard bump starting.

There is no way that I could think of to have bent a crankshaft from bump starting. Bent cranks come from hydro locking or physical obstruction.

Another item to look at is the engine mount bolts and flanges. Are any of them broken? Given that the engine starts and runs but gets worse as you increase the rpm's, something has been loosened in the engine or it's mounts which becomes more noticeable at speed. Your gearbox and the rest of the bike are fine, because they would not cause the issue you are describing because they are not in motion.

Worth looking into more closely. Especially given that the engine runs.
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Re: Bent crank?

Post by sixbennetts » Sun Nov 10, 2019 4:55 pm

scottmastrocinque wrote:
Sun Nov 10, 2019 8:31 am
First off, I'm very sorry that criminals did this to you. It is underserved and uncalled for. I despise thieves.

More than likely, they broke lose something along the drive line, more than likely at the clutch/flywheel. The drive line is designed to apply force in one direction, from the engine to the drive shaft to the wheel. Trying to bump start the bike, especially down a hill at speed and with the skid mark you describe, the forces would have been applied the opposite direction, from the wheel to the driveshaft to the clutch plates and flywheel. I have seen a few BMW flat twins damaged from hard bump starting.

There is no way that I could think of to have bent a crankshaft from bump starting. Bent cranks come from hydro locking or physical obstruction.

Another item to look at is the engine mount bolts and flanges. Are any of them broken? Given that the engine starts and runs but gets worse as you increase the rpm's, something has been loosened in the engine or it's mounts which becomes more noticeable at speed. Your gearbox and the rest of the bike are fine, because they would not cause the issue you are describing because they are not in motion.

Worth looking into more closely. Especially given that the engine runs.
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SCOTTMASTROCINQUE nailed it! Broken front motor mount! Cracked right along the frame. Rear engine mount cross-bolt was also loose. We lashed the engine down to the frame very carefully and creatively with 3 tie-down straps and cinched them up tight. Started it up, revved it up, and vibration is almost gone!! Took the straps back off quick so they wouldn't melt.

THIS IS GREAT NEWS!! THE ENGINE INTERNALS ARE *PROBABLY FINE!!

Bad news of course is that we don't think it can be welded without taking the engine out. My buddy *wants to try it, but he can't guarantee not involving the engine case itself in the arc because it's just too tight in there. Plus, there's a lot of road grime in between the mount and block that really needs to be cleaned out for a good weld to happen. He also thought of grinding from the outside in, then welding his way back out, but said that's only if we don't take the engine out.

Wonder if the engine can be disconnected and jacked up in the frame. Looks like there's enough room above it for a little clearence.

Anyways, I don't have a welder, so I'll have to AAA the bike to his garage, have him remove/lift the engine, clean it, grind it, weld it, and squirt some paint on it. Given the fact that the next 10 days are in the 30's here, and I ain't getting any older, we've decided to spray the area well with WD40 and park it for the winter to be tackled in the spring. Yes, I'm a weak little nancy-boy for not riding much in the winter!

I am relieved beyond words that we didn't have to crack the case, (provided the broken mount was the only thing wrong).

Thanks everyone for the suggestions, though. They're greatly appreciated, and scottmastrocinque, what kind of beer do you want!? :cheers:
I have a funny wife. Hilarious, really.
I love her, she loves me.
______________________________________
2007 Ural Retro, "Подарок солдата солдату"

"I'm slow and like to go old."
Plattsburgh NY

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sixbennetts
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Re: Bent crank?

Post by sixbennetts » Sun Nov 10, 2019 5:31 pm

Didn't take pics, 40° in my garage and getting colder! Here's a pic of the area that's broken from myural.com, an excellent resource for all of us.

Cracked whole section of square flange on the inside between frame and block. Talking to Van now, he says there's enough room to remove all engine mounts and just lift the engine in the frame, so maybe we can do that.
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I have a funny wife. Hilarious, really.
I love her, she loves me.
______________________________________
2007 Ural Retro, "Подарок солдата солдату"

"I'm slow and like to go old."
Plattsburgh NY

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sixbennetts
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Re: Bent crank?

Post by sixbennetts » Sun Nov 10, 2019 5:43 pm

A better pic from myural.com. This is the opposite side from where ours is cracked, but it shows the flange better.
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I have a funny wife. Hilarious, really.
I love her, she loves me.
______________________________________
2007 Ural Retro, "Подарок солдата солдату"

"I'm slow and like to go old."
Plattsburgh NY

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Re: Bent crank?

Post by snowymonkey » Sun Nov 10, 2019 6:27 pm

Glad to hear the good news man!
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