Another KDX200 Rebuild

[dedgery207]

Purchased a 2004 KDX200 in December for $2K. It started and ran well enough for me to take it to Hatfield McCoy for a four day trip last week. Really only riding it around my icey driveway here in New Hampshire before the trip, I felt like I was taking a risk trucking the bike all the way down to WV for a riding trip but thankfully the bike held together for four days of riding. Started well and ran decent. Now that I am back to NH and it is still winter here I decided now is a good time to freshen up the topend as I have no idea what this bike's maintenance was like it its previous life.

Pulled the cylinder head last night to find a decent gouge on the exhaust port side of the cylinder. My quick research says I need to send the cylinder to Millenium for repair and recoat? Should I have them supply a new piston and clean my powervalve while they have the cylinder? Had a brief conversation with them on the phone this morning and they would put a wossner piston in it and repair the cylinder (recoat as well).

Anyone use Wossner Pistons?

The cylinder head looks very clean without any indications of wear.


Dan

[KDXGarage]

Welcome. Thanks for joining. Is the gouge able to catch a fingernail?

[dedgery207]

Yes, I can feel it with my finger.

When you say "catch a fingernail" do you mean if it has sharp edges that my nail will catch? It does not have sharp edges but I can definitely feel it with pad of my finger easily.

[kdx633]

It kind of looks like the plating is worn off at top of exhaust port?

[Molly's 70]

"catch a fingernail" means if you run just your fingernail over it you can feel it.

[KDXGarage]

repair and replate

it might have been a chunk of carbon broke off from the top of that piston

[Goofaroo]

I used a Wossner piston in my 87 model. The plating service I used in Henderson NV recommended it over Wiseco and another brand they offered. That was about nine years ago and it’s still going strong.

[bufftester]

Wossner is a good piston. Replate it and you'll be good for a bunch of years

[dedgery207]

Sent the cylinder off to Millenium last friday. Does this look like the original piston? Also found the reed valve to have a small amount of its corner missing on the sealing surface. Does this change running characteristics drastically? I will replace with new.

[bufftester]

Yes, looks like an OEM piston, and yes, the reed valve not sealing fully will affect performance.

[KDXGarage]

I second what bufftester said.

[dedgery207]

Rebuilt the carb yesterday with 155 main and 45 pilot jets. New jet block gasket, new stock needle, bowl gasket and cap gasket.

It was warm in New Hampshire yesterday so new tires front and rear along with new tubes.

While I wait for my cylinder (6-8 weeks) I would like to rebuild the rear shock. Looking for suggestions and tutorials on how to do this. I have never rebuilt a rear shock. Got a quote from a well known local shop and it was about $260 without replacing the spring. I am thinking I could save 150 by doing it myself and offset the cost of a new spring. I weight 230lbs without gear. I am 30 y/o and an aggressive C rider. The bike will be used as an offroad biased dual sport (turkey runs and trail connecting. No slab only days). I ride rocky single track. Lots of baby heads and rocky hill climbs. May add an oversized gas tank in the future.
I have already installed .42 kg front springs, shim stack mod, and refreshed the oil in the forks. Rode the bike with the new fork springs at HM last month and it felt pretty good. Not overly stiff and reacted decent to sharp edged rocks a high speed.

I noticed that the rear shock was compliant but I struggled to carry speed on rocky hill climbs. The front would track straight and absorb the hit but the rear end would bounce and kick me off my line which then struggles to keep traction. I put the clickers to stock settings but did not have time to adjust during the trip.

Any suggestions would be much appreciated.

[KDXGarage]

It sounds like you are not afraid to jump in and get it done. Good job with what you have done for your KDX.

Would you be interested in buying a KDX KYB shock parts kit from me? If so, I have some shock parts on order so I can start selling shock parts kits again. The parts should be here this week. I will post a for sale ad in the "For Sale" subforum when they get here. It includes the following KYB (Japan) parts:

bladder
bumper
nut
piston band
piston o-ring
seal head

On the shock spring, a 5.4 should be about right.

[dedgery207]

Yes, I would be interested! In your opinion, pending no other severe damage, will the kit get me through a rebuild of the shock? I need to call around and verify that someplace local is willing to do the nitrogen recharge without rebuilding the shock themselves. I will do that this week.

Really appreciate you putting the kit together.

[KDXGarage]

Thanks. Yes, the kit contains the parts for a rebuild. Fifteen years ago (WOW!) I worked on members' suspension a few times, so I am familiar with the parts and techniques. You could do air in a pinch, but nitrogen is the preferred, proper way. It needs to be from a loss-less chuck also. A bicycle shop that does suspension work may have a nitrogen setup or at least a hand air pump with gauge and lossless chuck.

I usually had the kits for sale, but misplaced one of the parts, so I quit selling them for a while. I finally gave up on finding them and ordered more. They are supposed to be here Friday.

Here's a picture of a 1991 shock disassembled and somewhat labelled. The 1989 - 1994 are about the same as a 1995+ shock.

1991KDX200shockpartsModified.jpg (91.59 KiB) Viewed 2770 times

Here's a 1997 KDX200 shock.

1997KDX200shock.jpg (29.6 KiB) Viewed 2770 times

Here's my nitrogen setup with the Race Tech lossless chuck.

1991KDX200NitrogenFill.jpg (21.82 KiB) Viewed 2770 times

Here's the parts in the kit, all KYB.

KDXShockRebuildKit.jpg (167.06 KiB) Viewed 2770 times

[dedgery207]

That looks great! I am not sure how to send a PM so we can sort out the shipping. Do I need to donate to the site to get access to PM's?

[Goat]

Nice job on all this work! Looks like you will have a dandy.
Yes, this forum requires donation in order to use PMs.

[KDXGarage]

That looks great! I am not sure how to send a PM so we can sort out the shipping. Do I need to donate to the site to get access to PM's?

Hi. The site is run off donations and is ad free. Supporting members get PM access and another members only forum.

viewtopic.php?f=69&t=15658

Just e-mail me at kdxrider AT gmail DOT com

I have the parts in today, so I am able to sell the kits again. I am going to post a thread in the For Sale forum with details. Thanks!