[smoke4ndmears]

Since I got the bike, I'm starting a new thread off of my questioning if rebuilding the xx9 motors are economical.

Short story - Original owner suspected over-rev going into a turn back in 2015, motor started "pinging" or "knocking". Pulled over and hasn't been ran or looked at since.

I'm starting with draining the oil into a clean pan, inspecting the screen, and cracking the oil filter open, but beyond that this is a little new to me.

Should I be hesitant to crank it over with the plugs removed to listen for anything in particular? There's no way to easily look at the bottom end is there?

Thanks

 

[nlzmo400r]

One thing I’ve learned over the years is to never trust someone’s else diagnosis or even symptom description. The ‘knocking or pinging’ previous owner heard might just be a battered clutch basket or something silly.

That being said, did you find any shavings or debris in the oil, filter or screen? If not, dump clean oil into it and fire it up. If it’s already knocking it’s probably not going to die running at idle for 20secinds for you to hear it yourself.

To answer your question about checking the bottom end; there’s no easy way to check as the cases are split vertically. However, I’ve had some luck removing the spark plugs, putting a piston near TDC and pushing on it with a punch. Sometimes if a rod bearings spun, the piston will give way a little under your hand pressure without the crank spinning. That’s a pretty clear indication the bottom end needs disassembly.

To check crank bearings you can use a crank turning tool to manually turn it without spark lugs and feel for ‘grittiness’ or debris in the roller bearings that way.


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[duc96cr]

You can’t really see much with an inspection camera , I’ve tried. Drain the oil , check the screen. You could cut the filter open. The second thing would be examine the plugs. Third, do a compression check. Rotate the engine by hand with the plugs out, you might be able to feel something. If you can find an inspection camera with a small enough head on it you could check the cylinders and valves. Pop the valve covers and rotate the motor, you might see a bent valve or valve train issue. The first thing I always think on an over rev is valve or piston damage.

 

[belter]

comp test, leakdown, turning it over, if it runs without noises that make your skin crawl, give it an oil pressure test. if it has rooted big ends it'll have 40 - 50 psi oil pressure rapping wildly.

otherwise, pull it out and you keep pulling it apart until you find something wrong.

i had a 748r in once that had previously been diagnosed with a terminal bottom end failure due to the noise it was making. turned out an opening shim had come out. no idea how, but that's what it was. just follow the clues.

 

[smoke4ndmears]

Thanks everyone for the great information. Here is where I am after draining the oil:

 

[duc96cr]

That can’t be good. Time for the experts to step in. Warm up the wrenches.

 

[nlzmo400r]

Definitely doesn’t appear to be bearing material on the plug. I’ve seen plugs look similar before with no ill effects. I’d pour oil in it and start it to listen for yourself.


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[smoke4ndmears]

Unfortunately getting it to fire up might be delayed -fuel pump flange o-ring is no bueno after draining the last of the old gas. The shavings on the screen are somewhat worrisome as there is some copper in there. I'll continue to go through it bit by bit. Waiting on a thin-wall socket to get the plugs out and start turning it over. That will be today, so I might be posting more here.

Are the valve cover gaskets\seals re-usable?

Again, all of the dialogue is really appreciated!

P.S.
Anyone recognize this clutch:

 

[smoke4ndmears]

Well it's time to spin the motor with fire. Hand rotating (using the rear wheel) with the plugs out doesn't seem to be an issue. Plugs look fine. No noises or strange play in the drive train. Valve train area looks good and timing is correct. Pushed against pistons with a long t-handle allen wrench at TDC +/- and couldn't detect any slop.

 

[smoke4ndmears]

Some video\audio of the motor turning over using the starter with and without plugs\clutch pack

no plugs:

plugs\no clutch:

 

[smoke4ndmears]

One more video for funsies (and to get my post count to 30!). This time with no clutch and no plugs.
Maybe there is some knocking detectable with the plugs installed and the motor making compression? IDK. Compression test is next, just need to get a hold of a tester.

Is it ok to run the engine without the clutch pack installed?

 

[nlzmo400r]

You probably won’t hear any ‘knocking’ until there is combustion pressure on the piston. If you 100% saw copper material on the plug magnet, then you can be sure it’s rod bearing related aim which case a tear down is needed.

If not, and judging by sound alone, I’d put oil in it and run it. Compression and leakdown testing will not point to a rod bearing failure unless the failure is so bad youd would’ve already known otherwise.


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[smoke4ndmears]

Noted, thanks. No copper on the plug magnet but isn't copper non-magnetic? A few tiny slivers in the oil screen. Still haven't split the filter open.

 

[ducvet]

I will wager my .02$ on a main bearing failure.

Though my 749 motor had a broken rod when it appears a rod bolt fell out. the rest was destroyed by the owner finishing the lap.

 

[smoke4ndmears]

I will wager my .02$ on a main bearing failure.

Though my 749 motor had a broken rod when it appears a rod bolt fell out. the rest was destroyed by the owner finishing the lap.

Well, I did as Nismo suggested earlier and attached the crank turning tool and spun by hand with the plugs out. It didn't feel gritty, but maybe I could feel some slight rhythmic bumpiness of a bad bearing? Really hard to say it was very subtle.

 

[nlzmo400r]

Noted, thanks. No copper on the plug magnet but isn't copper non-magnetic? A few tiny slivers in the oil screen. Still haven't split the filter open.

Copper is non ferrous, but so is aluminum. If you felt no play at all in the rod bearings via pushing down on a piston just past TDC, and there’s no copper at all in the screen or filter, I’d wager there’s no rod bearings failure. Wear? Sure, but failure? No.


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[ducvet]

Not rod bearings but MAIN bearings, no copper there and you could not feel them by turning over the motor. If you pull the alternator cover and clutch cover and then remove the gears on the crank so that all you have is a crankshaft you then can often feel a bad main.

Before getting that far in you check everything along the way like the small bearing in the alternator cover. I just had a 1200 last year that had that bearing failure. go in slow and with eyes open that is steel to be on the magnet.

 

[belter]

that much fur on the magnet would be mains, loose flywheel nut or starter clutch ime.

 

[smoke4ndmears]

Thanks all. This is quite the fun learning experience, and I'm going deeper into motor issues than I have in the past. It's also a great excuse to buy new tools. I'll keep posting what I find. Maybe it won't be so bad?

Who am I kidding! Lol.

It's just crazy to think that a motor with 4k on it would be toast.

 

[smoke4ndmears]

Fuel pump is not cooperating, but I chanced a squirt of starting fluid down the intake runners. Clutch completely removed to eliminate the clankety clank. It sure sounds ok…

Getting it idling for more than 10 seconds on gas will be the real tell.

Got to talking with the PO, and he described the event as going into a tight right hander and instead of the slipper clutch engaging (not sure which brand he has on it) the motor caught the revs on decel, sounded knocky\pingy and wouldn't accelerate. He immediately pulled off and didn't attempt to start again. What would a slipper clutch do (sorry don't have much experience with them) if the fuel pump died mid engagement? Running super lean\starving for gas could explain maybe the weird engine noises?