ADVrider

Go Back   ADVrider > Bikes > Orange Crush > Crazy-Awesome almost Dakar racers (950/990cc)
User Name
Password
Register Inmates Photos Site Rules Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
Old 04-21-2014, 11:57 PM   #1
Jdeks OP
Departed
 
Joined: Aug 2009
Oddometer: 951
Question Tips for a first-timer doing a 950 head rebuild

Okay,

So I've decided to bite the bullet, and refresh the heads on my 100k old '04 950.

I know the valve stem seals need replacing. But I plan to have the valves lapped, cylinder re-honed, replace the cam chains, tension rails, rings, head gaskets and anything else that's sensible while I'm down there.

I've never done something this big before. I plan to follow the workshop manual, which I have, and any relevant bits from the HoW and ktm950.info.

But could anyone else who's done this job possibly offer some advice?

  • What exactly IS 'valve lapping', and how do I do it? Give it to a shop?
  • Same for cylinder honing?
  • How exactly do I replace piston rings? Is there a special procedure? Or just take the old ones off, and put the new ones on?
  • What else should I do/replace while I'm down there?
  • Any other tips or gotchas I should be aware of?
Cheers.
Jdeks is offline   Reply With Quote
Old 04-22-2014, 12:07 AM   #2
chasbo
Beastly Adventurer
 
chasbo's Avatar
 
Joined: May 2005
Location: Prescott, Arizona
Oddometer: 1,535
Good luck on your rebuild!
__________________
"Dakar must be a race for few people, Dakar is a dream, the dream of the Rose Lake, if everybody finish it, the dream is over" Fabrizio Meoni
chasbo is online now   Reply With Quote
Old 04-22-2014, 01:26 AM   #3
Chop Chop
Hector erector
 
Chop Chop's Avatar
 
Joined: Aug 2009
Location: Sunny Coast, Qld Aust
Oddometer: 1,669
Quote:
Originally Posted by Jdeks View Post
Okay,

So I've decided to bite the bullet, and refresh the heads on my 100k old '04 950.

I know the valve stem seals need replacing. But I plan to have the valves lapped, cylinder re-honed, replace the cam chains, tension rails, rings, head gaskets and anything else that's sensible while I'm down there.

I've never done something this big before. I plan to follow the workshop manual, which I have, and any relevant bits from the HoW and ktm950.info.

But could anyone else who's done this job possibly offer some advice?

  • What exactly IS 'valve lapping', and how do I do it? Give it to a shop?
  • Easy as, just need some valve paste and tool (basically a suction cap on a stick. Auto shops should have both. check youtube for videos.
  • Same for cylinder honing?
  • Nikasil coating, so I believe not recommended. You can get the barrels recoated if needed, but not cheap here in Oz.
  • How exactly do I replace piston rings? Is there a special procedure? Or just take the old ones off, and put the new ones on?
  • Pretty much what you said, just get the order right.
  • What else should I do/replace while I'm down there?
  • Any other tips or gotchas I should be aware of?
Cheers.
Still putting mine back together and no expert, so others can comment on stuff I have obviously missed and may need to rectify.
__________________
.

If you don't want the piss taken, stop giving it away!
Chop Chop is offline   Reply With Quote
Old 04-22-2014, 02:08 AM   #4
MacMan
Studly Adventurer
 
Joined: Jun 2007
Location: Outer NW Melbourne
Oddometer: 711
The process will take as long as it takes, but don't skimp on having everything measured properly.

You may find that the bores are actually very good. Nikasil is like that - so long as the engine has never ingested dirty air or water, the pistons and rings cop the brunt of wear.

Pistons almost certainly will need replacement, rings definitely.

At that sort of mileage, the valves will need thorough inspection and measurement including looking for stem wear. If they're out of spec the guides will be too.

Find a good machinist and pay what they ask to do a good job because a bad job is worse than none at all, and that's before you factor in what it cost. Just touching up the seats yourself is pointless if there are other wear issues.

Have fun. You'll learn a lot. Oh, and be clean .
MacMan is offline   Reply With Quote
Old 04-22-2014, 02:32 AM   #5
Dr AT
(KTM quack)
 
Joined: Jul 2006
Location: maffra, vic
Oddometer: 2,027
Quote:
Originally Posted by MacMan View Post
The process will take as long as it takes......

Oh, and be clean .
Rohan, perhaps book some leave, ask fozzie if you can watch him do the work +/- spend some time watching him do other jobs?
Dr AT is offline   Reply With Quote
Old 04-22-2014, 02:58 AM   #6
StevenD
Hmmmm, dirt!
 
StevenD's Avatar
 
Joined: Aug 2005
Location: Holland, Amserdammed
Oddometer: 1,111
would not supprise me if the pistons are good still, but yeah, measurement is required.
For the valves, just a suction and paste job will not do in most cases. Re-grinding at the correct angles and width is what you need to make it like new again on the seating area.

take your time and make friends at a good engine shop.
__________________
999 LC8 Rat-Rally custom - 500 EXC - XR666R '85
StevenD is offline   Reply With Quote
Old 04-22-2014, 03:31 AM   #7
Jdeks OP
Departed
 
Joined: Aug 2009
Oddometer: 951
Quote:
Originally Posted by MacMan View Post
Oh, and be clean .

This is an issue.

My living situation means my 'shed' is a communal storage shed out the back of the units, which I have been told NOT to clean out, despite having a good layer of dust and cobwebs.

Even if I did, it's literally a tin shed in a carpark. Air tight it aint, and theres construction machinery and mowers in the area on a semi regular basis.

Is this a deal breaker in its own right?
Jdeks is offline   Reply With Quote
Old 04-22-2014, 03:51 AM   #8
MacMan
Studly Adventurer
 
Joined: Jun 2007
Location: Outer NW Melbourne
Oddometer: 711


There are ways around any problem.
MacMan is offline   Reply With Quote
Old 04-22-2014, 05:22 AM   #9
Bowber
Gnarly Adventurer
 
Joined: Feb 2012
Location: Kirkby Stephen, Cumbria, UK
Oddometer: 130
I've never worked on the 950 beyond basic maintenance and inside the side covers but I've rebuilt and tuned racing engines for years.
A clean working environment is a must. A speck of dust isn't a problem but having dust blowing around and sticking to all the oily parts as you rebuild is a problem.
If you can not work in a clean environment your better off not doing the rebuild at all if the motor is running ok and not using loads of oil.
Take the heads and barrels off and then seal up the motor with bags and tape, then take the heads to somewhere clean to work on them.
You may need new valves and guides but measuring everything will tell you.
Old valves will need regrinding and the seats need cutting by a competent person with the proper equipment, then you can finish with a light lap to make sure they seal but if the seat cut and valve grind is done properly then they shouldn't need lapping.
I'd look at rings, valve seals and probably valves at a minimum with that mileage, nothing worse than a rebuild only to drop a valve a few months later but it depends on how hard the motor has been used.
Valve spring length will need checking as well as they settle just like any spring.
Hope that helps

Steve
Bowber is offline   Reply With Quote
Old 04-22-2014, 07:24 AM   #10
COXR650L
Beastly Adventurer
 
Joined: Nov 2009
Location: Denver
Oddometer: 1,464
What symptoms are you having that makes you think the top end needs to be torn apart?



Im just finishing up a rebuild on my 04'. My plan was similar to yours and just do the top end, however I went ahead and cracked the case. At 80k miles the main bearings were shot.

A lot of people say the bottom end will go forever (and Im sure I could have got several more miles out of mine) but there is no denying the bearing were worn towards the end of their life. At 100k I would bet you will be needing them as well and the reality is you will be in this overhaul close to $1k for the top end. It would be a mistake to not address the bottom end and waist all the money and risk trashing the engine with a bottom end issue 1 year down the road.

My advise, you are just wasting time and money pulling the engine and doing the top end without at least looking at the bottom end. FWIW.


For my rebuild I spent about $1700 and skipped over stuff I should have addressed but did not have the money for. $2500 would be the bare minimum for a "complete" rebuild on an 04 if you did the work yourself.

On that note:
I think you need to plan for a lot more top end maintenance at 100k, you may get away with less but understand the following may very well need to be done once you get in there and the cost will raise very fast:
-New valves/spings/guides/head work
-New pistons
-New cylinders



If I had to do it again, and especially coming in the spring riding season, I would buy a low mileage used engine

Good luck.

COXR650L screwed with this post 04-22-2014 at 07:37 AM
COXR650L is offline   Reply With Quote
Old 04-22-2014, 08:08 AM   #11
dirtbikebagger
Adventurer
 
dirtbikebagger's Avatar
 
Joined: Apr 2012
Location: minneapolis mn
Oddometer: 88
Honestly a dirty location and first time engine work both sound pretty sketchy to me. Headwork will likely cost you a grand or more. Without all of the proper measuring and machining tools you basically have to bring it all (jugs pistons heads lower end) to a machinist and say "make it fit". Then you just pick it up and assemble the engine.
I would be leaning towards a used low mileage 990 engine on ebay! Cant beat a factory built stock engine.
dirtbikebagger is offline   Reply With Quote
Old 04-22-2014, 09:24 AM   #12
crofrog
Beastly Adventurer
 
Joined: Sep 2007
Location: Annapolis Maryland
Oddometer: 1,455
I'd also _seriously_ consider just getting a low mileage used 990 motor off ebay.
crofrog is offline   Reply With Quote
Old 04-22-2014, 09:26 AM   #13
Qwik
Adrenaline Addict
 
Joined: Apr 2008
Location: Sunnyvale, California
Oddometer: 6,411
I found my 950 replacement engine for $1200. Hell of a lot cheaper than a head rebuild.
__________________
Speed bumps never seem to make me go any faster
Qwik is offline   Reply With Quote
Old 04-22-2014, 06:35 PM   #14
Jdeks OP
Departed
 
Joined: Aug 2009
Oddometer: 951
Thanks heaps everyone

I should first clarify - it's 100 000 km, so only about 60 000 miles.

Quote:
Originally Posted by COXR650L View Post
What symptoms are you having that makes you think the top end needs to be torn apart?
I'm getting a puff of smoke if I blip it in neutral, and signs of leaky valve stem seals (engine break down a hill and hit WOT, big cloud of smoke). Doesn't blow visible smoke otherwise during running, but oil consumption at about 500mL in 3000km (2000 miles).

Also finding the cam chain clatter is taking a bit longer to go away than it used to, and this is with the longer tensioner bolts.

Aside from that, it makes good power and runs like a clock. In all honesty I could keep riding it as is for a while, but winter is here now, and I have a BIG trip planned in the near future, so I don't want any unknowns.

Cam chains and sliders can be done with the engine in the frame (albeit with a bit of fiddling). But from what I know, to replace valve stem seals, you pretty much have to pull the head. I figured if I'm doing that I may as well go whole hog and rebuild the head, even if it is premature. I figured the bottom end would be right to leave though, based on reports of its longevity.

If there is a way to replace the valve stem seals without pulling the heads, then I'd probably just do that, replace cam chains and sliders, and keep riding.



Quote:
Originally Posted by COXR650L View Post
If I had to do it again, and especially coming in the spring riding season, I would buy a low mileage used engine
Quote:
Originally Posted by crofrog View Post
I'd also _seriously_ consider just getting a low mileage used 990 motor off ebay.
Yep. I've had several other people say this to me already. Seemes to be the done thing, actually. Not being in the USA, 990 motors are a little bit harder to come by here, but its still a feasible plan.

I guess I'm just sentimental about keeping my faithful motor going, and I also kinda want the learning experience.

But by the looks of things, it does seem a right daft thing to do, especially considering how much I'd have to pay to get all the machining done....
Jdeks is offline   Reply With Quote
Old 04-22-2014, 07:33 PM   #15
AJ990R
motorcycle guy
 
AJ990R's Avatar
 
Joined: Dec 2011
Location: MKE,WI
Oddometer: 206
installed valve spring compressor for motorcycle is the?

JDEKS,
-You've got the right idea. Your motor IS NOT used up & in need of replacement Replacing the engine is the easy way out IMO. You MOST LIKELY just need some intake valve seals cause the rubber is now hard as as a rock.
Not sure how mechanically inclined you are...or if you got an air compressor.
-Someones had to have done this!??
-A standard leak down tester adaptor to spark plug thread, hold the motor on a top of compression stroke, compress the spring somehow(usually requires a quick tap from a hammer, get extra keepers!), and change the seal with the head still installed...done time & time again in the automotive world(esp V8 BMWs).
-Only issue I see is the little valves for the motorcycle vs a car. Tried to gooogle it, can only find automotive "in head" compressors. You can easily cut up 3/8 deep sockets to work with small valves, but homemade special tools would require a welder...
-Not the end of the world to drop the motor for head/jug removal.(IF it ain't broke don't fix it!)
-Don't give up on her yet

CHEERS
AJ
__________________
"saddle up or shut up"
KaTooM North

AJ990R screwed with this post 04-22-2014 at 07:39 PM
AJ990R is online now   Reply With Quote
Reply

Share

Thread Tools Search this Thread
Search this Thread:

.
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


Times are GMT -7.   It's 11:27 PM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2014