Top end rebuild questions

pw455 · Post by **pw455** » 11:54 pm Sep 06 2015

Hi Everyone,

I've been browsing and learning from this site for the past year or so and ended up buying an '01 KDX220 earlier this year. So far I love the bike, minus the front suspension, which I'll be taking care of in the next few months.

I finally decided to pull the top end apart to see if it still had the stock piston. Things were looking pretty good until I pulled the cylinder off and looked at the cylinder walls and piston. There's pretty heavy scuffing which I can't tell if it's aluminum deposits from the piston or actual gouging.

Few questions:
1) Does the picture below look like there's damage to the cylinder or only deposits? I read that I can use muriatic acid to remove any aluminum deposits, but that it can also damage the cylinder if I'm not careful. Is that only if the Nikasil coating is worn away or will it burn through the coating as well? Do I use full strength acid or dilute it? Any tips would be great.

2) There are some areas around one of the ports that looks like the coating chipped off. I can definitely feel with my nail that it' a chip and not any kind of build-up. Is this reason enough to get the cylinder replated or should I not I worry about it?

3) Everything came apart easy until I got to the 3mm-headed allen screw on the KIPS rod. Unfortunately, even using a good socket and taking my time I ended up stripping the head. Any ideas on how to remove the screw?

Thanks,
Pete

Jim B · Post by **Jim B** » 12:37 am Sep 07 2015

pw455 wrote:I read that I can use muriatic acid to remove any aluminum deposits, but that it can also damage the cylinder if I'm not careful. Is that only if the Nikasil coating is worn away or will it burn through the coating as well? Do I use full strength acid or dilute it?

Everything came apart easy until I got to the 3mm-headed allen screw on the KIPS rod. Unfortunately, even using a good socket and taking my time I ended up stripping the head. Any ideas on how to remove the screw?

I haven't had any problem with it dissolving the coating, although I wouldn't leave it on there any longer than necessary. I've used it full strength with good results.

Heat, it may have thread locker on it.

Pictures aren't showing for me.

6 Riders · Post by **6 Riders** » 03:09 am Sep 07 2015

pw455 wrote: 3) Everything came apart easy until I got to the 3mm-headed allen screw on the KIPS rod. Unfortunately, even using a good socket and taking my time I ended up stripping the head. Any ideas on how to remove the screw?

You'll probably need an E-Z out for this. Also if this is the screw that hold the KIPS rod in the head, next time use an impact driver to loosen it up.

pw455 wrote:2) There are some areas around one of the ports that looks like the coating chipped off. I can definitely feel with my nail that it' a chip and not any kind of build-up. Is this reason enough to get the cylinder replated or should I not I worry about it?

Pictures aren't showing, use Photobucket or the likes to post pictures.
IMO, if there is that much wear, then it is time for a re-plate. I sent my cylinder off to Millennium (with the new piston kit) and they did an excellent job. I also had my cylinder cross-hatched before assembly.

Good luck.

gereonb · Post by **gereonb** » 11:31 am Sep 07 2015

Pictures are not working, try using a picture hoster or flickr for storage.

pw455 · Post by **pw455** » 11:51 am Sep 07 2015

Thanks for the replies so far. I think I fixed the pictures using photo bucket. Let me know if you still can't see them.

pw455 · Post by **pw455** » 03:53 pm Sep 07 2015

Just finished cleaning the scuffed areas with acid. It was clear some of it was aluminum deposited from the piston which I was able to remove, but most of the scuffing didn't react leaving me to believe it's damage to the cylinder. Between this and the chips near the ports it seems that it will need to be replated. If anybody thinks it's OK to use as is, please let me know.

Thanks,
Pete

motogoalie1 · Post by **motogoalie1** » 03:56 pm Sep 07 2015

I would replate that. It seized at some point. Looks deep.

pw455 · Post by **pw455** » 04:02 pm Sep 07 2015

The grooves really aren't very deep which I can barely feel with my fingernail. It looks pretty much the same on the other side of the exhaust port.

The guy before me was running 50:1 with Maxima 927. I've been running 40:1 since I bought it.

pw455 · Post by **pw455** » 05:16 pm Sep 07 2015

One thing I'm wondering is what normally causes this kind of damage; poor lubrication (not enough premix), reving a cold motor, lack of maintenance or something else?

6 Riders · Post by **6 Riders** » 05:37 pm Sep 07 2015

Dirty air filter and miles....

jjavaman · Post by **jjavaman** » 09:32 pm Sep 07 2015

That's not the reverse threaded one is it??
Have you tried the shim stack mod to the stock forks? I did mine last winter and it makes a big difference!

pw455 · Post by **pw455** » 01:18 am Sep 08 2015

Thanks for all the replies. Looks like I'll be sending the cylinder out to get repaired and replated as soon as I get the stripped screw removed. I'll check tomorrow if I have the right size EZ out at work.

6 Riders wrote:Dirty air filter and miles....

Wow, I clean mine pretty regularly, but this is definitely more incentive to stay on top of it.

jjavaman wrote:That's not the reverse threaded one is it??
Have you tried the shim stack mod to the stock forks? I did mine last winter and it makes a big difference!

No, the reverse thread nut didn't give me too much trouble and I supported the shaft with a wrench when I removed it. I'm talking about allen-head screw that holds the main valve to the kips main shaft just inside the KIPS cover.

I haven't tried anything with my suspension yet other than adjusting the sag and playing with the clickers. I had a WR250F before the kdx and the suspension is the one thing I really miss. I don't expect to get the front suspension as good as the WR without changing the front forks, but at least want to be able to take small jumps without feeling like I might break my wrist. I'll do a little more research and maybe start a new thread once I get the top end taken care of.

KarlP · Post by **KarlP** » 07:10 am Sep 08 2015

I would try heating that KIPS rod with a propane torch and getting a good grip on that screw head with some vice grips. You'll probably need to use a dremel to put some flats on the side of the screw head. The key is plenty of heat.
Don't worrow about the seals that go around that rod. New ones come with a gasket kit.

KDXohio · Post by **KDXohio** » 09:53 am Sep 08 2015

Go to harbor freight and buy a hand impact. Trust me it is money weeeell spent you will never strip strip those pesky engine screws again! A little pressure and a slight whack with a hammer will free the screw right up!

http://www.amazon.com/Lisle-29200-Hand- ... B0002NYDRG

Edit* Just saw the head is already stripped Ive had luck with forcing a SAE hex socket into the smaller metric head (takes a couple hits with a hammer to get it in far enough) then using the hand impact. If that doesnt work then weld a bolt/nut to the head and pull it out.

Jim B · Post by **Jim B** » 11:45 am Sep 08 2015

KarlP wrote:I would try heating that KIPS rod with a propane torch and getting a good grip on that screw head with some vice grips.

The key is plenty of heat.

This. I wouldn't hammer on that rod using an impact driver, you might bend it. Also, I don't think an EZ Out is going to do anything as the socket/hex is too shallow.

DJNiedz · Post by **DJNiedz** » 04:44 pm Sep 08 2015

pw455 wrote:Hi Everyone,

I've been browsing and learning from this site for the past year or so and ended up buying an '01 KDX220 earlier this year. So far I love the bike, minus the front suspension, which I'll be taking care of in the next few months.

I finally decided to pull the top end apart to see if it still had the stock piston. Things were looking pretty good until I pulled the cylinder off and looked at the cylinder walls and piston. There's pretty heavy scuffing which I can't tell if it's aluminum deposits from the piston or actual gouging.

Thanks,
Pete

What prompted you to take it apart?
I'm waiting until conditions get too crummy for riding to pull mine apart.

pw455 · Post by **pw455** » 04:52 pm Sep 08 2015

DJNiedz wrote: What prompted you to take it apart?
I'm waiting until conditions get too crummy for riding to pull mine apart.

The bike was actually running great, but I knew I needed to pull it apart to check for the stock piston. It's a good time for me since it's too hot for me to ride right now.

I also planned to send the carb and head to RB Designs to have them worked on while it's apart.

kaw814 · Post by **kaw814** » 04:19 pm Sep 09 2015

Thought i'd throw my 2 cents worth in. Good move on plating the cylinder. Those allen head screws gave me trouble too. Heat and pb blaster cracked mine loose. If not, ive had alot of success with extractors.

pw455 · Post by **pw455** » 05:08 pm Sep 09 2015

I called Millennium yesterday to check their pricing and lead-time and they said they can also disassemble, clean and reassemble the KIPS for another $50. He also said they'd be able to get the stripped head screw out for me. I hate to say it, but I ended up just shipping to them to have them take it out. I figure by the time I go buy a torch and waste more time trying to get it out I might as well just have them do it. I feel a little like I lost a fight, but saving the time seemed worth it. Thanks for all the suggestions and feedback though. Hopefully it'll keep me out of trouble next time. I'll let you know how it goes with the replating once I get it back.

Pete

KarlP · Post by **KarlP** » 07:41 am Sep 11 2015

Good move

I've screwed up plenty of stuff not wanting to give up.

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