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Need advice on reviving 91

Posted: 09:04 pm Aug 26 2019
by Yukon
Hello everybody, im new to the forum and knew to the kdx. Ive been eyeing up the kdx as a model that would fit my needs and desires for many years and have been searching for a project. Well i was fortunate enough to have a buddy donate a real project to me, for free, so its as good of a start as one can get, however im seeking advice from the professionals now if im taking the right path or if i should keep looking for a better start and use this one as a parts bike. So what i know i have is a solid frame with good neck bearings and what feels like a good smooth bottom end. Also what i know i have is the kips valves are absolutely obliterated, i cant even seem to pull the center exhaust valve out, seems to be wedging up on something, some pretty deep gouging in the cylinder and a small crack in the center top of the exhaust port. Wheel bearings and shock and swing arm bearing are shot, plastics are shot, radiators are questionable if they will hold water, and the carb boot has some pretty deep cracking. Im pretty handy around the shop and enjoy tinkering with bikes hence why im after a project. However looking for parts and pricing stuff out im wondering if this particular beast is worth resurrecting or if im better off searching for another bike, maybe even in kinda running order and keeping this one as a parts bike? Deep down inside i want to resurrect this one simply based on the fact a buddy gave it to me and id be proud to show it to him in its former glory come next spring, however im not so sure i want my free kdx to turn into a $4000 kdx. Looking for opinions and suggestions on wich way to go and best places for parts if i do tackle this.

Re: Need advice on reviving 91

Posted: 11:04 pm Aug 26 2019
by KDXGarage
Hello. Welcome to kdxrider.net. Congratulations on your KDX.

That one does sound very rough.

If you are trying to get the center valve out, I want to say the cylinder has to be off the engine, as it will hit the frame. I can not remember for sure.

What is your budget, money AND time?

Re: Need advice on reviving 91

Posted: 04:28 am Aug 27 2019
by Yukon
Cylinder is out. I can get the valve pulled out part way then you can feel it feels like it snags on something inside. My timeline is about 6 months, id like to get this thing togather in about 6 months and id be comfortable sending about 2 Grand on the project. I know what your thinking, for 2 Grand I could probably buy a nice kdx, but my issue is I can't afford to do 2 Grand all at once, it needs to be spread out alittle at a time.

Re: Need advice on reviving 91

Posted: 04:22 pm Aug 27 2019
by kdxsully
Maybe it’s just solidied sponge in the exhaust valves? Look up the hardest to get parts first. See if you can find them. Air boots for my KDX costs 185. Some insane prices for parts on these older bikes. Some stuff is irreplaceable, I think.

Re: Need advice on reviving 91

Posted: 04:56 pm Aug 27 2019
by bufftester
Honestly, it sounds like your buddy just wanted to make room in his garage...parts, especially engine parts, for the E series are tough if not impossible to find and just getting harder. There are a couple sources for KIPS sub valves, but I've not seen center valves available anywhere for a while. And you still haven't gotten the engine apart to see what other damage there is. Bearings are all available and easily replaceable, but not cheap. Rear linkage needs careful inspection. Radiators are easy enough to find, plastics a little less so. If the carb boot is not cracked all the way through no problem, if it is there are somethings you can do to try and salvage it, boots are a little tough to come by. You'll easily blow 2k on it if you decide to take it on IMO, but is it worth it? That can only be answered by you...I spent more on my hybrid build than it'll ever be worth, but it's worth every cent to me so...

And by the way, welcome to the forum!

Re: Need advice on reviving 91

Posted: 07:57 pm Aug 27 2019
by KDXGarage
I well reply later

Pull center valve out a little

Remove rod

Pull valve out

As best I remember

Re: Need advice on reviving 91

Posted: 09:09 pm Aug 27 2019
by bufftester
You have to remove the cover on the RH side of the cylinder and disconnect the KIPS actuator (it has LEFT HAND threads). Then you pull the center valve out to the groove, lift out the idler gear and lift up the subvalves and remove the actuator rod. Then the subvalves and center vavle come right out. This is the point where you need a manual.

Re: Need advice on reviving 91

Posted: 11:31 pm Aug 27 2019
by KDXGarage
I am running the mental cash register on JUST what you said was wrong. $1,100 at least.

You did not mention rebuilding forks and shock

tires, tubes?

chain and sprockets

air filter??

wheel bearings?

clutch (could be a small money pit for just the clutch)

The cylinder needs a repair and replate (close to $300 after shipping both ways)

new piston, rings, pin, circlips, small end bearing, gasket kit, coolant $200 almost

$180 or so?? for BDK Engineering (look on eBay) power valves

Throw on a new air filter.

You are at $700 before you even flip out the kickstarter.

Get on eBay / Rocky Mountain ATV/MC, etc. and price bearings, tires, sprockets, etc. before you spend a penny.



You are into it for ZERO right now. Research will cost you ZERO. Backing out will cost you ZERO.

Look around on Facebook Marketplace and criagslist to see what is available in your area. Those bikes will need work, too. You will get an idea on prices and such.

It is VERY easy to put $2,000 into it, and it be worth $1,200.

"measure twice, cut once"

Re: Need advice on reviving 91

Posted: 07:00 am Sep 01 2019
by Yukon
After a bunch of consideration and looking over the bike I believe I'm going to go for it. Honestly if I buy a bike in slightly better shape i could easily find myself needing to do just about all the same work in a year or so on the better bike. I might as well tackle it all right now and know what I have. There are certainly a few parts I may have issues tracking down but I'm sure it's do able. I've been obsessed with the kdx since a young age so this project I think will be worth while for me

Re: Need advice on reviving 91

Posted: 01:33 pm Sep 01 2019
by kdxsully
Yukon wrote:
07:00 am Sep 01 2019
After a bunch of consideration and looking over the bike I believe I'm going to go for it. Honestly if I buy a bike in slightly better shape i could easily find myself needing to do just about all the same work in a year or so on the better bike. I might as well tackle it all right now and know what I have. There are certainly a few parts I may have issues tracking down but I'm sure it's do able. I've been obsessed with the kdx since a young age so this project I think will be worth while for me
I like knowing what I have too. Can’t trust almost anyone when it comes to used bikes.. many sellers are just trying to get rid of their woes

Re: Need advice on reviving 91

Posted: 01:38 pm Sep 01 2019
by Kdxfan4130
Check the parts prices at partzilla and Babbitt’s app 10% off. Both offer great prices w partzilla free shipping after $150 purchase.

Re: Need advice on reviving 91

Posted: 04:52 am Sep 02 2019
by KDXGarage
All right. Here we go. :-)

At least you are starting at the right price!

Good luck on the build.

Re: Need advice on reviving 91

Posted: 09:08 am Sep 02 2019
by Yukon
Alright, so I have all the motor woes figured out with fredette racing, cylinder will simply ship there once I'm confident this project is worth doing. My next big mountain to figure out is the swing arm hole is egged out alittle in the bearing hole and the bottom shock hole in the linkage is pretty egged out. I'm assuming these need to be round for new bearings to push in and there probably isn't much tolerance for them to be out of round?

Re: Need advice on reviving 91

Posted: 12:49 pm Sep 02 2019
by KDXGarage
replace both

Re: Need advice on reviving 91

Posted: 02:42 pm Sep 02 2019
by kdxsully
Yukon wrote:
09:08 am Sep 02 2019
Alright, so I have all the motor woes figured out with fredette racing, cylinder will simply ship there once I'm confident this project is worth doing. My next big mountain to figure out is the swing arm hole is egged out alittle in the bearing hole and the bottom shock hole in the linkage is pretty egged out. I'm assuming these need to be round for new bearings to push in and there probably isn't much tolerance for them to be out of round?
KDX garage is right if you want it done right. Replace both. Otherwise, I guess you could use bearing retaining loctite.

Re: Need advice on reviving 91

Posted: 02:59 pm Sep 02 2019
by KDXGarage
You may want to look into buying another parts bike. You don't have a good starting point from a quality standpoint.

If you are close to north Alabama, I can sell you one.

Re: Need advice on reviving 91

Posted: 05:59 pm Sep 04 2019
by bufftester
If the bearing holes are not round the new bearings will not last long. a Competent machine shop could probalby fill the ovaled out portion and get it sized properly, but it won't be cheap. The right answer is as KDXG said .. replace them.