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Whiy'd my Big End Die? How to test DR-Z400 Oil Pump

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Hi all,

I'm coming to grips with the fact that my big end died, I have ordered a new Stock crank, and a Cylinder Works 434 BB kit...while I was replacing stuff (whole crank cheaper than rebuilding the orig in Aus) I might as well upgrade...

Anyhow, I'm preparing to put this bike back together, I bought it second hand from a local bike shop and had problems from day 1, it went back and had new cylinder, piston etc before I'd had it for an hour, which was devastating I couldn't get my money back unfortunately, I certainly tried, and I suspect that the big end damage was there before I bought it, but...I'm not sure.

I don't know what's caused it, I have read that if the o-ring is missing from behind the filter, this can cause probs, or maybe the bike ran without oil once upon a time? The o-ring was missing when I tore the engine down, unfortunately I usually assume things are right when I pull them apart and put them back how I found it, so I suspect the o-ring was never there since I've had the bike as I've changed the oil a couple of times a year since I've had it, so it's probably had an oil chance about every 500k (ridden about 2000km)

So my questions are: Anybody know what could have killed my big-end; and

How do I test my oil pump??

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Hi all,

I'm coming to grips with the fact that my big end died, I have ordered a new Stock crank, and a Cylinder Works 434 BB kit...while I was replacing stuff (whole crank cheaper than rebuilding the orig in Aus) I might as well upgrade...

Anyhow, I'm preparing to put this bike back together, I bought it second hand from a local bike shop and had problems from day 1, it went back and had new cylinder, piston etc before I'd had it for an hour, which was devastating I couldn't get my money back unfortunately, I certainly tried, and I suspect that the big end damage was there before I bought it, but...I'm not sure.

I don't know what's caused it, I have read that if the o-ring is missing from behind the filter, this can cause probs, or maybe the bike ran without oil once upon a time? The o-ring was missing when I tore the engine down, unfortunately I usually assume things are right when I pull them apart and put them back how I found it, so I suspect the o-ring was never there since I've had the bike as I've changed the oil a couple of times a year since I've had it, so it's probably had an oil chance about every 500k (ridden about 2000km)

So my questions are: Anybody know what could have killed my big-end; and

How do I test my oil pump??

I the o-ring is missing, the oil will partly flow around the filter, but it will still flow.

To check if the oil pump is working; fire up the engine, and open the bolt right over the acct/mcct on the right/back side of the cylinder.

If ok, the oil will pump out the hole.

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I the o-ring is missing, the oil will partly flow around the filter, but it will still flow.

To check if the oil pump is working; fire up the engine, and open the bolt right over the acct/mcct on the right/back side of the cylinder.

If ok, the oil will pump out the hole.

If I might suggest.

Prior to starting the motor and checking for oil flow.. What was the condition of the pump? Gears, and case (which is the oil pump "housing")??

If those items are undamaged, or only lightly so and repaired / replaced.. then the next step is oil flow as correctly stated above :thumbsup:

If you have already confirmed the pump is good, then disregard.... :blah:

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lets not forget any blockages that could restrict oil flowing through the system from blocked screens or damaged feed lines .

there is a point where you have confirmed the oil pump is sound , now you need to run the motor to confirm oil flow .

start the motor .. you should see the presence of oil flow out of the hole as mentioned .

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I imagine your bike had been poorly maintained prior to you buying it and a lot of damage was the result. The big end has been a ticking time bomb.

Had your oil pump gone bad, you cams/head would be the first to suffer.

I bet the failures have been caused by the previous owner not changing the oil, perhaps submerging the bike and not immediately clearing all the water/do numerous oil changes to flush it out, letting the bike sit in a damp environment after shut down for long periods.

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Hi Guys,

thanks for the replies, I should have asked, is there a way to determine whether the oil pump is good while I have it out of the motor?

Thanks William 1, there's no wear on the cams or their journals, everything looks sweet in the head, so I suspect you are correct, it may have been drowned and killed the big end that way.

So at this point my plan is to re-assemble the motor with replacement parts, start it and the first thing I do is check that the oil pump is working by cracking the bolt above the ACCT.

Thanks again guys.:thumbsup:

Cheers.

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Might be a good time to clean the the frame downtube oil screen.

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How many miles where on this before it let go ???

Don't forget to replace your Main bearings when you replace your Crank. also check all the other bearings as there might be some other damaged ones in there:thumbsup:

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7,800km on the bike when it got too ugly sounding to ride it any more.

I'd had the timing chain replaced by a local Suzuki mechanic thinking that was the noise, they didn't even pick it up which surprised me...

Decided I was better off doing the job myself to save on labour, I probably should have done the timing chain as well...

Cheers.

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you need to do all the loctite fixes

Yep, got it apart, so I may as well, I've seen a list of them all here, so I will be printing out instructions and carrying them out...got a monster bottle of loctite so all good.

I've already done the water pump RTV fix.

Anything else to know about?

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read the instructions on the loctite. Too many guys just goober some on the threads and tighten down the bolts. You must clean all of the oil from the threads first and be sure to mix or shake the thread locker if it is liquid. I use acetone to clean oil off of parts.

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