Kawasaki KX200 rebuild

Spac · 2020-03-08T06:32:10+00:00

You are a glutton for punishment.

Spac

Have made progress!

Swapped the flywheel and stator so that I can plug it into the CDI box I have .... I don’t think there was anything wrong with the original stator, but it was easier to swap the parts than work out & modify the wiring.

Now has spark!

Apologies for the crappy photo- it’s the only one where I captured a photo of the spark.

This era of Kawasaki have failure-prone exhaust power valves (essentially VTEC for 2-strokes, yo). I was genuinely surprised that this motor’s valves had only failed in one way - usually they are a huge mess of stripped gears and flogged out everything.

New ones are unobtainable. But because I am me, I had a new pair of genuine valves already.

They die from a combination of wear and becoming gummed up with sludgy, unburned 2T oil.

So all of the old bits need to be scrubbed clean. Such a fun job...

The bit that really sucks is getting them timed correctly on reassembly. There’s three elements that have to match the rack and each other - about three quarters of the time, they were put together wrongly the last time someone had them apart. Including this time.

It is easy to get them wrong because they are a prick to assemble in every way. Counter intuitive, bits wanting to fall out, referenced from open but goes together from the fully closed direction etc. The 1980s Japanese engineers clearly wanted the round eyes to suffer.

And suffer I did.

Looking back up the exhaust port, this photo is supposed to show the sub-port fully open (5:30 position in the photo).

And fully closed in this photo. /\

The variable exhaust port height is easier to show. Fully closed:

And fully open (with the photo flipped 180* even though I did not more anything):

The collars at the top of the PV drums wear and get loose, leading to premature PV wear. Simple, and surprisingly effective solution is to centre punch to outside of the collars - this leaves a raised section around the centre punch mark which stops them rattling in their bores.

Next was a new Chinabay piston. It seems to be reasonable quality, actually.

And all buttoned up. Compression was good, but now is excellent.

I need to dig out a 5mm circlip from my stash before I refit the cover for the actuating mech.

If everything goes well, then tomorrow I should be able to try to fire it up. It won’t have an exhaust or coolant so there won’t be any laps of the backyard, but should be a useful boost to my motivation which has obviously been waning.

Spac

I lied about the coolant. Got a bit motivated and sorted the radiators after all.

Bit of messing around with the lower radiator hose - it was too long.

Not the prettiest, but does the job. And the exhaust pipe will hide it...

The LHS power valve cover is a resonance chamber. I have a larger aftermarket one from back in the day which I was intending to use...

...but it gets in the way of the lower radiator hose and I didn’t have the correct (longer) bolts. The original went back on instead.

It runs!

Started on about the third kick, even.

Fuel pours out of the carby, and it is absolutely deafening without any exhaust, but it runs!

Still have a million little things to do, and obviously the pipe is still a bug thing to do, but most of the way there now.

Spac

Side project!

paid a token amount for this. A 1998 Yamaha TTR250.

My motivation is because it is from the 1990s and is purple! :)

Story is that it had been run low on oil and it killed the crank.

Previous owner got as far as removing the motor, and left it long enough for mud wasps to make a mess of everything.

I pulled the top end off, and the crank is perfect. Hmmm...

Time to go digging. First up was some removal of the mud wasps.

Some very minor porting, just because I was in there.

Also bead blasted the ports to be sure that there was no mud left floating around.

Anyway, I found the actual problem. Both of the inlet cam journals have galled - not horrendously, but...

The above photo shows them after I have attacked it all with the scotch brite pad. A mate has looked at it and reckons that it will be ok. If it isn’t, a replacement head is about $300 from ebay.

Next step was to order some new parts from ebay: Piston, cam chain, gasket kit and intake manifold. All dirt cheap - came to $150 or so in total.

Remarkably, the intake manifold turned up today, less than a fortnight after I ordered it.

Spent Saturday afternoon on the bike. Nothing big, just a bunch of tidy-ups: fit fork boots; new front brake pads; bleed the brakes; fit some grips and hand guards; swap tyres etc.

After a few hours of casual work...

Today was cleaning mud wasps out of the carby. Separate to the mud wasps, the choke plunger had seized in place and I snapped the brass shaft trying to remove it.

Of course, I forgot to take photos along the way, but here’s the repair. It was vastly more complicated than it looks - basically, there’s a hand-drilled hole in the narrow part of the shaft and the pin from a pop rivet soldered in. Then it is soldered into the larger diameter piece.

The soldering killed the rubber O-ring that seals the choke off when it is closed.

Managed to wedge a new O-ring in there.

Seems to work fine, but I won’t know for sure until it’s on a running motor.

Now I just have to wait for the rest of the parts to turn up.

Slowbrick

The purple wheels are very cool. Me likey.

Spac

Chinabay piston and intake manifold seem quite good.

Chinabay timing chain is garbage and has more slop than the used one.

Still waiting on the gasket kit.

Got the motor in and the new piston on. Not very exciting but slow progress is still progress.

Spac

And the gaskets turned up.... Got a bit done before the kids got home from school.

Head is torqued up, cams are in but the cam caps aren’t torqued down yet.

Drained less than a cupful of oil out of the sump... Bit nervous about whether there’s any other damage, but there’s only about an hour’s work to get it running/find out if anything else is wrong so full steam ahead. ?

PaddlerEd

We've got a TTR around here as well, also resplendent with Purple bits:

Like many bikes around here, it's set up more for dual sport/adventure riding than out and out trail riding

Spac

Light duty ADV bike is definitely on the cards for this one.

Have kind of got this dirty idea of riding down to the Barossa on it, racing the 24 hour and riding home. Maybe.

Ex850R

Spac
Light duty ADV bike is definitely on the cards for this one.
Have kind of got this dirty idea of riding down to the Barossa on it, racing the 24 hour and riding home. Maybe.

too old

PaddlerEd

We did the Scrapheap Adventure Ride (Delz did... me and Jon used (an equally) cheap Discovery in 2016 with our under $1,000 XT600

That was about 800km there and 700km home.... there were 2x XT600s in our group, and the only problem was if Delz stopped riding in the rain, it would cut out - keep riding, and it was happy!

Spac

It runs!

Starts and idles fine, but pops and misfires when you open the throttle up.

Here’s the new oil after literally two or three minutes of running...

It now has a new filter and a second lot of new oil. I figure that it will probably have to be replaced again after another five or ten minutes of running... Hopefully that will be how long it takes me to get it running right.

Motor sounds healthy, suggesting that the cam journals are going to be OK. Has all gears and clutch/gearbox all seem to work as they should.

Spac

Update on my old dirt bike shenanigans:

A) TTR sold for small profit.

B ) Ugly 1986 KX200 untouched.

C) Nearly finished 1990 KX200 untouched.

D) Project 1987 KX125 purchased, and mostly finished. Waiting on new mudguards and some motivation now. Only a couple of hours work to finish it.

E) Very ugly 1988 KDX200 project bike purchased from a mate.

F) Ugly, but running 1987 KDX200 purchased from another mate. If I had known that this one was coming up, I wouldn’t have bothered with the first one.

G) 1986 KX125 project purchased (actually, I accepted it as part payment for another bike I sold). This was a nice, low hour bike that blew the engine some time ago, pulled apart and was stored poorly. Basically, the motor is junk now ?.

Here’s the plan to dig myself out of this self-inflicted quagmire:

Finish the 87 KX. Race VMX on it, because I need to improve my raw speed.Build a decent (not immaculate) 87 KDX200 out of the best parts, to use in local Vinduro events.Build a nice 86 KX200 from F & G to race the A3VE on. Finish the ugly 86 KX200. Because I have so many parts to choose from, it will end up a fair bit less ugly than it was - but still won’t be a pretty bike. Sell whatever is left over to try to be slightly less broke.

Have started on the KDX build. I have the two roughly complete bikes and the remnants of another two, so there’s plenty of parts to choose from.

People always hack at the frames of these bikes - apparently from a misguided, futile need to try to “modernise” the look of them. The best frame still needed a muffler mount welded on.

Plastic restoration is slow and tedious, but ultimately very rewarding.

TL_V70

I had a mid 90s KDX 200 built 220 motor FMF fatty pipe Vforce3 reeds ect I loved it it was a amazing bike to ride and EVERYONES loves the smell of 2 stroke in the morning. I wish I never sold it but that life

Spac

Fuel tank tidy up. This was the roughest of the 125 tanks that wasn’t completely trashed.

It is destined for the ugly 86 KX200. Because I never remember to take “before” photos, here’s one after I had begun to scrape the sun damaged plastic off.

There should be some brass inserts moulded into the tank, but it is common for people to jam too long bolts in there and/or for corrosion to seize the bolts in. Either way, they end up spinning the inserts in the plastic and damaging the tank.

This one had been “repaired” in the past, using 6mm nuts and epoxy.

One repair had held and is ok, the other had fallen out.

I chipped away the epoxy as best as I could (which was not well).

Tank was intact and should still seal, which is a huge relief - definitely something I should have checked before spending hours sanding the outside!

Photo from the inside of the tank - the dark nipple on the left is the recess for the missing insert.

No photos of this because I was too busy doing rather than trying to be instafamous, but I trimmed a bit of plastic from a mudguard, and melted it into the hole using a soldering iron.

Then grabbed a 6mm flanged nut, turned it upside down and melted it into the hole.

It actually looked very neat at this point, but I got nervous about it pulling out, and “soldered” some more material over the flange. This is far uglier, but the radiator shroud covers it.

Threading a bolt into the nut and pulling it as hard as I can doesn’t budge, so I think that is a win.

Won’t know for sure until the bike has a few hours on it...

Spac

Also, footpegs.

These pegs have a real habit of flogging out the holes, and then instead of sitting nice and flat, they point down at the ground

First step is to weld up the holes. Note the inclusion penis on the bottom right. I missed a big lump of grime when I cleaned the pegs, and this is how it punished me. It was hollow, so was easy to remove with the die grinder.

Next step was to cut up another two pairs of pegs to make wideners, and then weld them on.

This gives your boots more grip, and spreads the load on big hits/heavy landings.

One pair will go onto each of the 86 KX200s.

They still need a tidy up with the linisher, but beats paying $200 for aftermarket pegs.

Ex850R

Good idea!

I see some grid mesh bits being made into footrests!

Spac

Hello chaos, my old friend.

Spac

Jebus, I am terrible at before photos.

These bikes don’t have an adjustable idle mixture screw. No idea why - presumably Kawasaki saved $0.30 per bike and that was totally worth denying users the ability to tune their bikes properly?

Anyway, I recently realised that all of the castings are there to fit a mixture screw.

So this is the experiment.

First up, use a 5mm drill to mark the centre of the cast hole.

Then drill the hole to 3.0mm until it breaks into the air hole.

The air passage has a brass restrictor pressed-in to set the air bleed. I forgot to take the Before Photo, but I drilled it out to 3mm which is the size of the “normal” Mikuni cabs with an adjustable mixture screw.

Now to wait for the M6x0.75 thread tap to arrive, and we can see if I am a genius or a moron who has just ruined a rare old part.

Spac

Progress on ‘ugly’ 86 KX200.

The forks are hurting my brain. No springs, they slide up and down beautifully.

Springs drop straight in, but then lock the forks up. I am guessing that they are too big in the OD, and as soon as they compress at all, the OD of the springs gets larger and they jam inside the fork tubes.

It seems to happen in the first couple of millimetres of travel though, which is weird.

Spac

1987 shock in 1986 frame is a tight fit... Have filed down the reservoir as much as I dared (which wasn’t much), and spaced the shock over to the left within the mounts. The reservoir just touches at full droop, but clears with any compression.

The downside of spacing the shock is that it takes away space for the intake boot on the other side.

Carby is a nightmare to work on. New Mikuni VMs are cheap to buy and are physically a bit smaller and come with an adjustable mixture screw. Will investigate.

Remember how I talked about how the pipe was bent and the previous owner had cut the original subframe rather than straighten the pipe? Well, it gets better... the pipe is still straight and still fits perfectly.

So anyway, it runs. Noisy AF with no muffler, so I didn’t run it for long.

Need to get rid of the 240 wreck tomorrow... Making this rideable will be my reward for getting the 240 on the trailer.

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