Jump to content
Sign in to follow this  

Top End Damage and Replacement

Recommended Posts

Hello everyone, my first post.

AqjM3iy.jpg

 

I bought a 2002 DRZ400 S for $850 that ran very loudly and clearly with something wrong.  The bike had 9k miles on the clock, so I hoped it wouldn't be something so catastrophic that the entire engine needed replacement.  I've pulled of the head and cylinder.  Here's what I've found.

The intake cam was dry and looked like burnt oil.

rIdgmoL.jpg

 

The intake cam journals were all eaten up.

 

BURyviK.jpg

 

The exhaust cam and journals look good though, which seems strange to me if the head was starved of oil.  Maybe just an oil channel for the intake cam was blocked?

 

Bottom of the head:

CIgm262.jpg

 

Cylinder and piston:

 

lWv92W0.jpg

 

mJcjHgv.jpg

 

hLnJq86.jpg

 

There was side-to-side play but no up and down on the rod:

Fns7EWv.jpg

 

Frame oil screen, I think that's case sealant gunked up on it?

HFq5wxl.jpg

 

Here's the link to the full album on imgur: http://imgur.com/a/cl1n1

 

So what can be used, and what needs to be replaced?  What went wrong in the first place?

I want to get this back to running as inexpensively as is reasonable.  Obviously the head needs to go.  Can the cylinder be reused?  I wiped it out with WD40 and a paper towel, but didn't have anything to really scrub with. There isn't any lip that I could feel where the piston stops at the top of the cylinder.  How about the piston?  Could it be reused with new rings?

Share this post


Link to post
Share on other sites

piston and cylinder looks fine, get rings and a new head = good to go

 

better check the oil pump though, and do the locktite fixes. 

Share this post


Link to post
Share on other sites

piston and cylinder looks fine, get rings and a new head = good to go

 

better check the oil pump though, and do the locktite fixes. 

Great, thanks.  Is all of the crud built up on the cylinder head and piston oil getting past the cylinder rings, or from running too rich?

 

Anyone have an extra intake cam they'd sell?

Share this post


Link to post
Share on other sites

Great, thanks. Is all of the crud built up on the cylinder head and piston oil getting past the cylinder rings, or from running too rich?

Anyone have an extra intake cam they'd sell?

Pm sent

Share this post


Link to post
Share on other sites

That motor looks like it was recently rebuilt (that doesn't necessarily done right), atleast good enough to sell it (piston and a cylinder hone) .

Id sell it, cause you don't know what else is lurking or the previous owner has done, could be a real money pit. But too late your already into the repair, crank doesn't look attractive either.

Edited by Spud786
  • Like 1

Share this post


Link to post
Share on other sites

That crank doesnt look good either (hot spots from oil starvation) id rebuild the top and bottom if i were you

Share this post


Link to post
Share on other sites

Great, thanks.  Is all of the crud built up on the cylinder head and piston oil getting past the cylinder rings, or from running too rich?

 

Anyone have an extra intake cam they'd sell?

 

 

could be the wiper leaking a little oil, but nothing to worry about. you have it apart now, so it's time for rings and a cleaning. the cylinder looks GREAT, so clean it with some PBBlaster but don't hone it. the cylider has a carbide coating that is very thin.   make sure your piston to cylinder clearnance isn't too large and you're good with those parts. 

 

when you start looking for cams, cylinder head, etc  ... if you find another head make sure it comes with the cam caps, as they're line bored at the factory and mated for life with the head. some folks have recently discovered this for themselves while trying to piece together bikes that had head problems. it's not pretty :(

 

 

:) good luck 

Share this post


Link to post
Share on other sites

That crank doesnt look good either (hot spots from oil starvation) id rebuild the top and bottom if i were you

The hot spots you are seeing are from the crank assembly process. Perfectly normal. That being said, this motor has suffered some sort of oil starvation episode, and the bottom end is suspect just because of that fact.

Share this post


Link to post
Share on other sites

Use a scotch brite pad to clean the cylinder bore, soapy water clean n dry, install the rings dry.  DRZ cylinders are Nikasil coated, the rings need a first start dry condition to seal.  The con rod small end and wrist pin should be oiled.

 

There are shops that will reweld and machine your head, don't know the cost.  Weigh cost against a good used head.

Share this post


Link to post
Share on other sites

Check the plastic oil pump idler gear... bet you find it broken.

If not check the oil pump and case cavity which is part of the oil pump.

When the head is damaged like that, you have to realize it is the LAST thing  in the oil path..IOW if it is damaged, all other items before it were oil starved as well. 

I would not reuse the crank and main bearings . Hot Cranks replacement for both.
Good used head that has been rebuilt by a known quality shop like Fast Heads.. new valves, springs, cotters and seals.. guides and seats checked and replaced as needed.

Yes you'll need a new intake cam, dime a dozen on fleaybay or used market. 
 

No you can not reuse the head and base gasket.. you will want new ones.

Share this post


Link to post
Share on other sites

Check the plastic oil pump idler gear... bet you find it broken.

If not check the oil pump and case cavity which is part of the oil pump.

When the head is damaged like that, you have to realize it is the LAST thing  in the oil path..IOW if it is damaged, all other items before it were oil starved as well. 

I would not reuse the crank and main bearings . Hot Cranks replacement for both.

Good used head that has been rebuilt by a known quality shop like Fast Heads.. new valves, springs, cotters and seals.. guides and seats checked and replaced as needed.

Yes you'll need a new intake cam, dime a dozen on fleaybay or used market. 

 

No you can not reuse the head and base gasket.. you will want new ones.

 

The plastic idler gear is fine, and everything turns over smoothly.  Maybe not a good indicator, but I can't feel any play in the bearings.

 

 

Not much to see, but does the video help?

 

I'm definitely concerned to not see a definitive culprit.  

 

What really seems strange is the intake journals and cam to be so far destroyed and the exhaust cam and journals are fine.  The exhaust area must have been getting plenty of oil while the intake was eating itself alive.  With the head being last in the oil path and exhaust side getting oil, would that suggest the rest of the engine was getting oil too and there was a blockage just to the intake?  There was a lot of what I assume to have been case sealant in the frame oil screen.

 

I'll get a gasket set.  The base gasket just looks brand new.  Maybe it was recently rebuilt and whoever did that messed things up putting the head back on...

 

I'm looking for excuses not to split the case!

 

 

Use a scotch brite pad to clean the cylinder bore, soapy water clean n dry, install the rings dry.  DRZ cylinders are Nikasil coated, the rings need a first start dry condition to seal.  The con rod small end and wrist pin should be oiled.

 

There are shops that will reweld and machine your head, don't know the cost.  Weigh cost against a good used head.

 

Thanks, I had put some oil on the cylinder.  I'll clean that off to install the piston and start the bike.

 

 

could be the wiper leaking a little oil, but nothing to worry about. you have it apart now, so it's time for rings and a cleaning. the cylinder looks GREAT, so clean it with some PBBlaster but don't hone it. the cylider has a carbide coating that is very thin.   make sure your piston to cylinder clearnance isn't too large and you're good with those parts. 

 

when you start looking for cams, cylinder head, etc  ... if you find another head make sure it comes with the cam caps, as they're line bored at the factory and mated for life with the head. some folks have recently discovered this for themselves while trying to piece together bikes that had head problems. it's not pretty :(

 

 

:) good luck 

 

Tips on checking the piston to cylinder clearance at home?  With the piston in the cylinder there is enough wiggle room to slightly rock the piston on the sides where there isn't a skirt. On the sides of the piston where there is the skirt, I can't feel any rocking.

 

I should have a head on the way with cam caps included!

 

 

That motor looks like it was recently rebuilt (that doesn't necessarily done right), atleast good enough to sell it (piston and a cylinder hone) .

Id sell it, cause you don't know what else is lurking or the previous owner has done, could be a real money pit. But too late your already into the repair, crank doesn't look attractive either.

 

Haha, I am committed now.  This will at least be a learning experience.

Share this post


Link to post
Share on other sites

I think the ex journals are the last point in the oil path?

Most of the time the ex journals get the beating?

Could a passage be plugged with sealant

that makes for this specific situation?

Check the workshop manual. It has a drawing of the oil path

Edited by jhondius

Share this post


Link to post
Share on other sites

I think the ex journals are the last point in the oil path?

Most of the time the ex journals get the beating?

Could a passage be plugged with sealant

that makes for this specific situation?

Check the workshop manual. It has a drawing of the oil path

Blocked?

Yes sure it's possible

 

The only one I've personally seen blocked was the cylinder oil gallery jet [JET, OIL GALLERY CYLINDER 09493-80005 ]for the head, placed in the case before cylinder install

Share this post


Link to post
Share on other sites

If there are no oiling issues, and all damages is limited to the intake cam...

 

Are they OEM cams?

Any indication the intake cam cap was replaced? ( paint pen markings from a used parts house or stories from the PO)

Share this post


Link to post
Share on other sites

you can use a feeler gauge to check the clearance between the bore/piston, max/min specs are in the manual. everything above the rings will be much looser, everything below the rings, tighter. honestly, that bore looks fine, piston too. looking at it from across the internet though ;-) 

 

hmm. maybe the PO did a valve check, and left the cam cap loose, or stripped the bolts and didn't realize it ? (check for helicoils)

 

maybe the PO lost the cuntershaft sael, and ran the bike without oil, damaging the head journal ? 

Share this post


Link to post
Share on other sites

If there are no oiling issues, and all damages is limited to the intake cam...

 

Are they OEM cams?

Any indication the intake cam cap was replaced? ( paint pen markings from a used parts house or stories from the PO)

 

They look like OEM cams, no indication of cap replacement.

 

 

you can use a feeler gauge to check the clearance between the bore/piston, max/min specs are in the manual. everything above the rings will be much looser, everything below the rings, tighter. honestly, that bore looks fine, piston too. looking at it from across the internet though ;-) 

 

hmm. maybe the PO did a valve check, and left the cam cap loose, or stripped the bolts and didn't realize it ? (check for helicoils)

 

maybe the PO lost the cuntershaft sael, and ran the bike without oil, damaging the head journal ? 

 

When I took the caps off, the four bolts holding the intake cap on seemed loose... I thought that might have been the PO pulling it off to take a peek and then not torqueing it down when he put it back together. One of the bolt holes had a lot of grit in it, so I think the bolt was loose when it was running... 

 

 

I think the ex journals are the last point in the oil path?

Most of the time the ex journals get the beating?

Could a passage be plugged with sealant

that makes for this specific situation?

Check the workshop manual. It has a drawing of the oil path

 

Great tip to check the oil path drawing... it looks like since the cam chain was getting oil, the problem should be isolated to the intake cam. The damage is so specific to the intake cam...

 

 

 

I've got a new head and cams should be on the way soon, any recommendations for a gasket set and piston ring set? Would these gaskets work? Link: Gaskets Should I look for after market or OEM rings?

Share this post


Link to post
Share on other sites

The plastic gear in the video is the waterpump gear , not the oil pump gear

You can't see the oil pump gear from down the cam chain tunnel, as its behind the clutch basket

 

Have you physically checked the plastic oil pump gear behind the clutch basket - the clutch cover needs to come off

Edited by GuyGraham
  • Like 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×