New to the forum and hoping to start a 220 build!

[ClayWhit]

Hi guys!
I've been a lurker for some time; I love the following the KDX has. I've been wanting a KDX for some years now (currently only have an 2001 XR650r but really want a trail bike for single track) and have been waiting for the right one to jump on, and I think I might have found the one. I found this on the KDX Facebook group, completely disassembled and includes an alleged $3000 worth of brand new parts (he's asking $1500). I've been looking for a relatively decent 200 or 220 to do a frame up rebuild this winter. This one is almost perfect for my vision, my only hesitation is I have never been rebuilt an engine, let alone try to put one back together without having the knowledge of how it came apart. The current owner says that the bike came with all the new parts (see attachments), with random new bottom end parts. He said the only thing that was taken off the bike when he acquired it was the clutch side. He then disassembled the entire motor and says the bottom end is in surprisingly good shape, but the cylinder needs to be replated. I'd love the opportunity to learn how to rebuild bike engines, I'm pretty handy and can do most of the work on my bikes just haven't had the courage to open engines. With the help of a shop manual, is this a job I can take on? I think this is a good opportunity to completely overhaul the bike and save some money on parts I'd likely want to replace on a complete bike that I'd buy anyway. What are some recommendations for things to replace while the cases are split, and recommendations for places to replate the cylinder? Thanks in advance for any advice and when I eventually start my build I would love to post updates here! I will attach some photos of the current state of the bike and included parts

[SpruceItUp]

Welcome to the forum! That's quite the predicament. If it was me I'd probably buy it. If you're wanting to learn, this is certainly not a bad way to do it, though it'll take a lot of patience. Plus it comes with the service manual! It's nice that the guy seems to have the parts organized pretty well and they seem relatively clean to me from what I can tell from the photos. I just wonder why they would go through the trouble of taking it all apart, buying new parts and then listing it online at quite a loss.
You can get the cylinder replated by Millennium or Powerseal. I've only worked with Millennium, but I've personally not heard anything negative from Powerseal.
From the parts he has it seems like it'll be a really nice bike once it's put together. I typically justify my bike purchases by being able to part it out and sell it and make my money back plus a bit. I don't think you would have any trouble with this bike making the money back if it's only going for $1500. Justified!
I'd replace all of the bearing in the bottom end and of course the crank seals along with the crank bearings. It's already apart so you minds well replace them all. And a new piston if there isn't already a new one, and send that piston to millennium/powerseal when they replate the cylinder, they will get a perfect fit.
Take a good look at the transmission parts while you're there checking it out/buying it, so the gears, shift forks and drum.

Best of luck!

[JimmyB]

Welcome ClayWhit, well that is interesting, like SpruceItUp mentions and what I like is he is well organized, not everything just dumped into a tote, as long as everything is there, some parts now are getting hard to find or if originals damaged (kips Valves, governor rod) they can add up quickly. He has a lot of new parts and you won't have trouble getting your money back with just them, looks like new pipe, silencer, all new plastic, clutch basket, engine gaskets, rear sprocket, could also have some bearing kits in the 1st pic. Parting out the original bike parts I think you wouldn't lose there also, is there a tank, seat and airbox? Just looking at the photos check the right(center) engine case, has a couple of odd marks (dark grey spots @ 12&2 o'clock positions) around the lower crankshaft area. For sure it is a project but when buying a used bike most would give them a thorough going over and you are already halfway there. With the manual and from help on here and select videos putting it back together would be a good project and peace of mind it is in good shape.

[ClayWhit]

Thanks for the reply's,
Im really excited about the idea of learning the ins and outs of the motor, albeit intimidated. I would certainly replace all the bearings and I'm thinking probably send the crank with it to be inspected/rebuilt while I'm at it. Also reading up on engine mods, porting, head, and carb. So apparently the current owner purchased it from someone who didn't know anything about the bike other than that he acquired it from a client who passed. I'm assuming the fellow who passed is the one who purchased all the new parts. The current owner is the one who acquired it, found the bad cylinder and says the bottom end is in good shape. He's been very transparent with me and willing to work with me being that I have a busy schedule in the summer and the bike is 6 hours from me.

Also, there is more things included aside from the photos I added, a seat stock exhaust, another swingarm, and two sets of radiators.

I'm just hoping to find time really soon in a busy fire season here in Utah to make the drive!

[VTMTcowboy]

Welcome!

Looking forward to seeing it all come together. Good luck!

[bufftester]

Would be a great winter project for sure. 2 Stroke motors are easily built using mostly common hand tools, and just a few specialty tools that aren't all that much (case splitter/crank puller, torque wrench, things that you should probably have anyway if you're going to work on your bikes). Looks like most everything is there, and some of it is the aftermarket stuff you would want to get anyways. Definitely a bargain.

[ClayWhit]

Thanks for the motivation guys!
Hoping to go pick the pieces up on Monday if all goes to plan. I'm wondering if there's a crank puller that anyone would recommend, I don't want to end up with a janky setup. Or any other tools I should invest in for rebuilds. I already have a torque wrench, and a pretty full toolbox of the basic stuff.
Also, I'm been looking for a bottom end bearing kit, wondering if there's kits I should stay away from or just go OEM

[SpruceItUp]

Thanks for the motivation guys!
Hoping to go pick the pieces up on Monday if all goes to plan. I'm wondering if there's a crank puller that anyone would recommend, I don't want to end up with a janky setup. Or any other tools I should invest in for rebuilds. I already have a torque wrench, and a pretty full toolbox of the basic stuff.
Also, I'm been looking for a bottom end bearing kit, wondering if there's kits I should stay away from or just go OEM

I believe that tusk makes a crank puller/installer for a decent price, I've not heard anything negative.
Make sure you have an inch pounds torque wrench as well, if that's not what you already have.
I don't have a 220, so I can't speak for it exactly, but I always try to go OEM with crank bearings, if you can find them.

[Chuck78]

Hey, that looks like a great opportunity right there, if you happen to have the labor time required for a full rebuild! Doing it that way eliminates any guesswork of previous owners negligence or poor workmanship, as well as potential poor quality aftermarket parts... And on top of that, you get the bonus of learning how everything in the bike goes together and how it works together, which should then in turn help you in understanding any issues that come up down the road from normal use or even if you happen to make a mistake, you might be able to more easily pinpoint what went wrong.

With all of the used parts available online and auction sites etc, I would not even consider rebuilding OEM KDX forks whatsoever, but this will be a very good basis for an awesome Trail bike, especially if coming off of an XR650L, it will feel feather light, but the stock forks are so much heavier than virtually any other Fork option that you would be able to choose to fit onto the Spike as an upgrade, it's not even worth running them or rebuilding them in my opinion, not to mention the excessive underhand of the outer tubes below the axle, as well as always always requiring aftermarket fork springs because they are sprung for a 125-130lbs rider at maximum, with no gear.

2004 YZ250 forks, 2004-2005 KX250F forks (identical bike/forks as 2004-2006 Suzuki RM-Z 250 apart from the plastics and graphics), and I believe 2003-2006-ish KX125/250 2-stroke forks are all 48mm KYB open chamber forks, with the donor bike front wheel axle and triple clamps, which after a good woods revalve, will be about the lightest thing you could possibly run on there outside of a direct bolt-on swap of KLX300 forks and triples (KDX250 1991-1994 triple or 1991 KX125/250/500 triples will have an aluminum steering stem and be even lighter and should be the same clamping diameter as the KLX) are also the easiest and a more direct bolt on, and they will still use the KDX front wheel, but then you're stuck with the spindly 15 mm KDX/KLX axle.

For single track and technical trails, I really like the prospect of using the Honda XR400 forks, which should be a slight bit lighter than stock, but can still use the stock KDX triple clamps as both forks are 43mm tube right side up aka conventional forks. The XR400 forks may look very similar to the xr650 forks, but internally they are much better, and are a cartridge very similar to the KDX forks but with slightly better valving, although I would still recommend a revalve if not just adding Race Tech gold valves and using their online digital valving calculator software to get it set up properly. I believe the first year or two were 0.39kg springs, the rest were 0.40kg fork springs. Right side up forks have the advantage of not being so susceptible to mud getting packed down past the dust seal and into the oil seal where it will cause a guaranteed leak in short order compared to conventional forks. The outer tubes I would put some fork protector guards on, just the straight tubular kind that snap around the fork tubes, after wrapping them with some clear 3M vinyl protective wrap with adhesive backing has to not chafe the aluminum tubes.
The XR400R forks will require the XR wheel also, because they use a slightly larger 17 mm axle, which is a bonus for adding a little bit of front end rigidity so that the front end does not twist around so much in ruts roots and rocks.

If any aggressive high speed riding or racing is in the cards, a Honda CRF250X front end is a nearly direct bolt on, triple clamps and wheel included, and is a closed chamber fork. It still, like nearly every fork out there, could still use a good revalving for woods riding initial plushness, even though the X model is already a woods bike. This bike and it's fork valving is quite well documented on Thumper Talk and other forums. The clothes chamber forks are a little tougher to get to be the plush as possible compared to an open chamber fork, but they do much better over extended rough sections as far as not suffering from damping fade. They are designed similar to your rear shock, with a remote reservoir and a piston or bladder that completely separates the air, or rather nitrogen charge in the shock, versus the damping oil. Open chamber forks will suffer from emulsification of the oil after lots of rapid suspension actions blasting through choppy rough sections, and emulsified oil, mixed with air, foamed up, will be much lesser viscosity and therefore will give you damping fade until the oil has a chance to de-gas and settle down back to its normal state without significant amounts of air bubbles mixed in.

The shock will benefit greatly from doing a Race Tech Gold Valve and their valving calculated with your custom inputs.

For KYB forks and shocks (Showa makes those CRF250X forks), if you don't want to deal with the whole rebuild yourself, I'd highly recommend sending the shock and whatever KYB forks you choose, off to Jeff Fredette at FRP Off-Road, for rebuild and revalving. He is an absolute expert on KYB, but doesn't work on Showa brand products. Showa and KYB are the two big Japanese suspension makers that appear on most bikes. Yamaha uses KYB almost exclusively, Suzuki uses Showa almost exclusively, but Honda and Kawasaki seem to switch back and forth using both in the same model you're depending on the model. Sometimes the 250 will have one brand, while the 450 of the same model will have the other, or for the two-stroke era, the 125 will have the other brand...

Once the bike is in running order, suspension and tires are always the best place to put the money first, or to put the most money in terms of modifications. It makes a world of difference.

[Chuck78]

Also, on the 220, I would absolutely send that head out to Ron Black of RB Designs if you can get him to respond to your emails. He is basically fully retired but still will occasionally do KDX 220 head modifications for people. You can simply just have the head milled down to achieve 1.0mm of squish clearance @ TDC as installed and torqued, but this will require running high octane or running octane booster without taking any out of the chamber to put the volume close to stock.
This makes a MASSIVE difference in performance, throttle response, and jetting consistency on a 220.
Make 100% certain you check the dowel alignment pin length and the depth of the bores in the cylinder and head, because as I have learned, this is a common problem for compression leaks into the cooling system on a KDX when people Mill the head but do not grind some length or height off of the dowel pins. The head gasket will not ever be able to be fully torqued if you run out of depth in the bores of the dowel locating holes.

This is basically mandatory on the 220 in my opinion. The stock squish band height clearance is fairly large, which makes the squish design head profile almost ineffective vs a tighter clearance down to 1.2mm or 1.0mm (with thermal expansion and rod stretch at 7500 rpm, that 1.0mm is much tighter, so you don't want to push it any tighter of a static stationary cold measurement than 1.0mm for most. A very tight fresh bottom end can run 0.80mm squish perhaps, but that might become dangerously tight as the crank bearings age and wear.


Is that an FMF Gnarly Desert pipe I see there? Or Gnarly Woods? I can't make out the size and profile from the angle of the photo. They are both marked Gnarly and or Gold Series in the logo stamping, but the diameter and shape are different as well as the part # stamped into the upper hanger. The 220 does great with all three aftermarket pipes, especially the Pro Circuit Platinum 2, but if you don't like the 2-stroke powerband hit, I'd highly recommend the FMF Gnarly Woods pipe for more smoothness of power delivery as well as better lugging range stall resistance below the normal RPM range, and the power shifted down some for more low-mid range torque and even easier front wheel lofting. The Gnarly Woods pipe on a 200H for me is absolutely mandatory, but for the torquey 220's porting is optional as it cuts back on the high RPM power some.

Lastly, static ignition timing within the range of the 3 marks on the stator plate makes a HUGE difference in the performance characteristics of the engine. More advanced will give explosive low end power and very rapid throttle response, but cuts high rpm power back substantially. On the other end, more static ignition timing retard will make the low end a bit dull and non-responsive, but boost the top end rev out power substantially.
The hand built ignitions that two KDX enthusiasts have designed and built in small batches make it so that you don't have to have the compromise, so that they have a more broad range of power. A two-stroke, with the pressure waves and expansion chamber design, operate the opposite of a four-stroke in terms of ignition timing. More initial advance gives you much more low-end power, but pulling the timing back at high RPM due to the pressure waves will give you more top end power. This is sort of the opposite of a four-stroke ignition curve.

There's an aftermarket PeakRPM or MaxRPM CDI box for $59 or so that advertises up to 1,000 RPM more top-end power than stock for many models, and I believe this basically does the same thing. The hand built small batch versions have adjustments on them to change the timing curves a bit, but this cheaper one is fixed. You would need to play with the static timing of the stator plate in order to get the best setup, but it would basically just have one best setting instead of being able to choose top end power versus low-end power and response.

RE-VMX ignitions I believe is the company, they reached out to the community to see if anyone near the Virginia Maryland area had a water cooled KDX200/220 bottom end to loan out to them to design a system to fit our bikes '89-'06 with the exception of the less than common '91-'94 KDX250 (a heavy pig in my opinion), so there might be something coming out from them in the future, but if they use the Vape / PowerDynamo ignition stators and flywheel rotors, they eliminate the woodruff key on the crank and make a fixed stator plate and have you adjust the timing by rotating the flywheel on the crank.
While I daily drive Volkswagen TDI turbo diesel engines that use this type of interface on the camshaft to adjust the cam timing perfectly, with absolutely no slippage ever, I still prefer the keyed crankshaft setup, however on my Montesa VR250 Rickman engine, the PowerDynamo flywheel never slipped...

[Chuck78]

The bottom line is, get the suspension set up right and get some good tires on there for single track riding, and you will have an awesome bike regardless. However, my additional suggestions will just take it a bit beyond just a normal great KDX...

Check in here regularly with your progress, as well as any other tips and tricks you're looking for. There's a lot of ways to lighten up the KDX and improve upon things like using a KX brake pedal and a 93 and older KX or a Yamaha YZ 2000s shifter to get aluminum components to drop weight, as well as ditching the factory KDX kickstand which I think is absolute garbage, and running a Trail Tech billet kickstand from a steel frame Yamaha YZ from the early 2000s such as a YZ 125 up through 2005. The bracket needs modification and it's best to weld a reinforcing tab onto the frame if you are to use the lower chain roller tab to bolt this Trail Tech bracket onto.
I would highly suggest just selling the stock forks to someone in need and upgrading to the KLX 300 forks at minimum or the XR400R forks. Put the money into a better quality set of forks that weigh noticeably less and have external rebound and compression adjustments to make it easier to dial in, as well as getting rid of that excessive underhang of the outer tube below the axle which can get caught on roots and rocks....

Best of luck, and welcome to the KDX community! These bikes were so mass produced that there are still a very large amount of them out there providing their worth and validity on the trails!

[SS109]

I'm late to the party as always... looks like a fun time to me.