So you think you ran your big end bearing?

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lecap

Bachelor Dog
Joined
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Suzuki DR650
Nice to see that this branch of the forum deals with all XT's and XTZ's

This nasty little problem can also be found on "all" of them: The single cylinder XT & TT500; XT & TT600, XTZ660; XT660R, X and Z.

Yes, a problem almost four decades old and never resolved. So stop hassling your friend about his KLR and its doohickey.


The problem:
A hard, metallic rattle. It sounds fairly similar to a perishing big end bearing. The reason why many an XT in the past was sold way under value ::) Bought too :D

Diagnosis:
The bike has been properly serviced and not too badly abused, never ran without oil and does not have the mileage to make a thrashed big end a likely scenario.
If you can't tick those points off your big end might be ruined :-\

Start her up and allow the engine to warm up.
Give a bit of throttle to allow the engine to deliver some power and to prevent it from stalling immediately. Hold onto the front brake or just stand with the front wheel against the garage wall.
Put her into first and slowly release the clutch.

The rattle should smoothen out and disappear immediately before you stall the engine when a lot of torque is transferred through the primary drive.
Feel free to try this a few times. If you just get it to stop rattling once you've confirmed that your big end is propably as healthy as a pig in a puddle and the repair bill will likely be some 15 Gorillas less :cheers:

The source of the rattle is the engines primary gear.
The nut holding the primary gears on the crankshaft has loosened and deformed its lock washer.
Nothing will fall apart right away or get thrashed to bits but action is still required since the key locating the gears on the shaft will get smashed up with time.

I will continue & add piccies later.
 
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