Anyone know anything about V-Twin Air Cooled Japanese Bikes? My brother-in-law just bought a VStar 6

upshiftoverdrive

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As the title says. Please check out the attached video.

I know it's not good, wondering if anyone can pinpoint this scary knocking?

I'm wondering if the timing is off and the valves are kissing the piston a little bit? Probably too easy, the sound is pretty catastrophic. I am scared to run the engine more than 10 seconds at a time.

Thanks for any help!

[video=youtube;zfT0FHDz2ew]https://www.youtube.com/watch?v=zfT0FHDz2ew&feature=youtu.be[/video]
 

Motogiro

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Sounds like it may be in the top end in the valve train. I would not run it any more and pull the valve cover to inspect cams and valve clearance. That could be a valve that is stuck open for a number of reasons. or even a broken shim that has give too much clearance between the tappet and the cam lobe hence the slapping. Terrible sound! Don't run it anymore.
 

FinalImpact

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Ditto.... inspect now. New purchase or did this happen while out and rode it home?

Could be a busted valve spring too. Do you have access to a shop manual? With either jug at TDC when on the firing stroke, all valves on that jug should be closed.

It sure sounds like top end and down one cylinder. You'll find it soon I suspect.
 

TownsendsFJR1300

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upshiftoverdrive

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Thanks for the help. I posted on the VStar Forum (No Replies) and was considering posting on a bigger V-Twin Forum but decided that you knowledgeable folks could most likely help me out best!

We pulled off the tank, intake, valve covers, and cam sprocket cover. Not much to be seen at the cam sprocket, everything looks a-okay.

FinalImpact nailed it, it's the front jug that isn't firing right. Every other firing of the cylinders is rough, aka the front cylinder is not happy and that is where the sound is coming from.

Going to adjust the valves which are grossly out of spec and report back.
 
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TownsendsFJR1300

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At least with the removable cylinders, (short of trash in the crankcase) the top end is easily accessible and repaired...

BTW, an engine is an engine is an engine. Different designs but basically the same.

That bike is easier to work on as the engine is not a stressed part(with the frame) and everything is more open than the FZ
No WP, no shims, cylinders separate from the block, etc...

I think you'll find the knocking is either valve or piston issues. Hopefully they didn't ruin the lower rod bearing.

What year is the bike (for parts look up)?
 

upshiftoverdrive

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Yeah that's what I've been telling my brother-in-law. He's all bummed out because he adjusted the valves to perfection and it unsurprisingly made no difference.

It does kind of sound like a lower rod bearing to me, though I have no experience to base that on. I can't imagine anything in the top end making the loud squeal like that.

If it is something like the main crank bearing I feel like we may as well scrap the engine, or drop it for easier access.

https://www.youtube.com/watch?v=pYleKxjl0uY <--- Going to try this test next to see if the rod bearings are gone.

Does anyone know if its possible to get the head off without dropping the engine? Clearance looks like it may be an issue when taking the head off, with how close it is to the top tube of the frame.

The bike is a 2001 Yamaha VStar 650 Classic
 
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TownsendsFJR1300

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You should be able to pull the head (and cylinders) in the frame. It only has to rise maybe 3/8" to clear the alignment pins.

Once the cylinder is off, you can pull up and down on the connecting rod to check if the lower connecting rod bearing is toast.

The parts diagram:

Yamaha Motorcycle Parts 2001 V-STAR CLASSIC - XVS650AN CRANKSHAFT PISTON Diagram

Shows "standard, solid bearings", (not needle bearings) and NO over sized bearings.

If the PO dogged it bad enough, no oil changes, it is possible he spun that cylinder bearing.

*If the engine is still assembled enough to run, pull the spark plug wire from that cylinder, ground it
then start the bike. If the noise lessens you KNOW is that bearing. (You don't have that cylinder firing, making power
that would make the noise louder.

Buying a used crank rod and bearings would be the way to go unless he can swing a new crank and rod.

That engine should be pretty easy to tear down. No water pump, pull the clutch, everything on the right side,
leave the transmission in, etc..

Biggest thing would be the correct puller for the rotor. (I've had the shop pull the
rotor for me while I waited on my old KLR, tipped the kid $5.00)
 
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