Hey guys, new on here just have a few questions about a Blown up DRZ400 i bought recently.

I picked it up for a steal because it has engine issues, the seller told me the cam chain tensioner had failed and

jumped a tooth on the camshaft so i was hoping for a cheap easy fix.. maybe a new piston and valves.


Unfortunatley the damage is far worse, as it turns out the guy has been running it with next to no oil for whatever reason,

i dont know if he forgot to refill it after servicing or what but the piston has basically broken in half (see pics) and punched a hole

through the cylinder wall into the water jacket (also see pics). When i drained the oil it was mostly water because of this.


Luckily i have a mate who recently did a big bore kit on his DRZ so he has a spare piston and cylinder. The head came out quite well only

needing new valves, valve quides and the valves reseating. The cam journals have a tiny bit of scoring but it shouldn't be a problem.


The conecting rod on the otherhand has a bit of side to side play and some up and down play also.


at this point it looks like i'll have to split the cases, inspect everything and replace the crankshaft. Then put it back together with my mates piston and cylinder and the rebuilt head.


My question is, Is there anything else i should look out for? Im not sure how long it was running low on oil because the seller wont answer his phone. Any tips or advice is appreciated. Thanks









Wow,  that is some damage,  so did the seller mislead you in a way?

up and down play on the crank = garbage!


Clean, clean clean evrything!   that much carnage : it must have a lot of debris in the base.


clean the oil pump very well and inspect. it can have small scoring, but nothing too major.


I would've loved to hear the sound that made. Get a parts washer or lots and lots of cans of carb cleaner. Then just take everything, and I mean everything apart/clean/inspect it. Since the crank and tranny share oil you'll want to do the cleaning to the transmission too. 


This is why I always leave myself enough room in my purchase price to rebuild the whole motor when I buy bikes that don't run. 

Cheers guys, when I get the chance to pull it apart I'll do as suggested. Hopefully everything in there is usable besides the crank, I managed to source a used crank that's in great condition so I'm happy about that.

The buyer didn't exactly mislead me, all he knew is what he's mechanic told him that it is probably the cam chain tensioner.

With the price I paid I'll still be able to finish the rebuild and still walk away with quite a cheap bike because I'm doing all the work myself.

Luckily the head wasn't damaged because they're almost impossible to find in Australia and when you can they're ridiculously expensive.

Cheers, Josh

When I split my 400s cases I flashed all components with diesel using a weed sprayer(hand pump). You don´t need high pressure, just high flow. Then everything get WD40 "cleaned" , dried with compressed air and into Zip lock bags with good labelling. The carb/ brake cleaner have some effect on the o-rings.

carb cleaner is bad on oring...but brake cleaner is ok.

Where in AUS are you ?

Thank guys. I've split the cases and the gearbox and bearings seem ok but the crank has had it and so have the crank and counter balancer bearings.

I'll replace the bearings and install a new crank then I can chuck the cases back together then there's just a little head work before it can go back together.

I'm located in Sydney mate.


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