Air-cooled Hybrid - first ride report

[arjay]

The collection of Ebay pieces finally completed their long incubation and met the dirt for the first time today (first for a long time - me and the bits).
Initial observations - it runs really well, and the handling is surprisingly competent. Not sure what I was expecting really. The'87 KX piggy back shock came with valving that was way off original, and the RM forkks' valving was pretty out of whack too. At least it was all fresh and rebuilt. The aftermarket triple clamp was also 3mm less offset.

Anyway, no nasty surprises. I took it to the local off road park (deep sand, sand whoops, sand forestry single track, sand everything...and lots of polished 45 degree roots). A baptism of fire for an air-cooled small bore!

It stayed nice and straight on the fast sand tracks and turned beautifully with just a hint of body language. The suspension soaked up the high speed shallow sand whoops without any drama. Turning into the tight single track showed up slightly slow steering. This required a more physical approach to keep it on line. Nothing that felt like it couldn't be sorted out (the bar mounts were quite far forward, and the forks were flush with the clamps). The bike tracked beautifully over the bumps ad roots, despite a slightly harsh feel to the forks.

Power was great for the trail. The meat of it is in the top end, but it has a long and smooth mid range. It did feel a tad soft though, until the PV opens and the top end comes in. I got used to riding a higher gear than I would on my 125, and dabbing the clutch to get into the power. It still feels like it should have a bit more torque though. Maybe it's the FMF pipe and tail pipe (I seem to remember way back that the FMF made the power pipey). I'll also try the original needle for the 88 PWK.

All in all, for a test ride, it was an absolute blast. Hammering down the trail rather than Youtube armchair racing. With a bit of fettling this should make a great woods bike.

'87 KDX200 engine, FMF pipe
'86 KX125 frame and swingarm, Fastway pegs
'87 KX125 shock
'98 RM125 forks, front wheel
Applied Racing billet triple clamps
'89 KX125 subframe, airbox, seat, side panels

Talon rear hub, 18" KX rim

 

[Tom68]

Nice, tanks good but a bit more shrinking and forming would make it perfect.

 

[sr5bidder]

great job enjoy!!

 

[Rich Rohrich]

Well done :cool:

 

[Joburble]

Cool.

 

[whenfoxforks-ruled]

Way cool and nice job also! Vintage Bob

 

[smahala1286]

Awesome build!

 

[arjay]

Thanks for the feedback. It was a very satisfying moment buzzing through the singletrack on a bike that had never previously existed :)

 

[Tom68]

Even nicer up close, well done.

 

[ws6transam]

I'm partial to air hammers and that one looks GREAT!

 

[Porkchop]

North island or south ?

G-day Arjay, That's a fine piece a hardware you've built your self, great job.It kinda reminds me of a bike the king built while he was with team green, to ride in the isde.
It was a kx 80 motor, placed in a kx 125 chassis. That particular year the six day turned out to be a mud fest, every one got stuck at one point or another in the muck, well that bike was way easier to mussel around than all the other heavier bikes .
Mr. Roesseller earned himself some gold on that bike, & so can you. Have fun!
I've got a couple of pals from the land of the great white cloud, maybe you know some of them. The list of suspects are Slapper, Moose, Tim, & the Kiwi bird. This pack of HOOLIGANS & I have had some great rides & camp trips, an awesome bunch of characters they are! Have fun on your new ride, Cheers Mate, Porkchop... :nod:

 

[arjay]

G-day Arjay, That's a fine piece a hardware you've built your self, great job.It kinda reminds me of a bike the king built while he was with team green, to ride in the isde.
It was a kx 80 motor, placed in a kx 125 chassis. That particular year the six day turned out to be a mud fest, every one got stuck at one point or another in the muck, well that bike was way easier to mussel around than all the other heavier bikes .
Mr. Roesseller earned himself some gold on that bike, & so can you. Have fun!
I've got a couple of pals from the land of the great white cloud, maybe you know some of them. The list of suspects are Slapper, Moose, Tim, & the Kiwi bird. This pack of HOOLIGANS & I have had some great rides & camp trips, an awesome bunch of characters they are! Have fun on your new ride, Cheers Mate, Porkchop... :nod:

Cheers Porkchop, I'm glad I've got an extra 120cc to lug my non-championship ass around. I looked up LR's KX special but couldn't find any pics. Did find out that it was built using 89 models. I haven't met the hoolies yet - there agin I haven't been out much over the last 3 years - a situation that I wil be putting right very soon :ride:

 

[glad2ride]

WOW! Great job!

 

[arjay]

This has been in the shed for a while while i had a fling with a Husky 144. I'm back on it now and looking forward to getting it dialled in again. (This thing is 10+ lbs lighter than my Husky, hence the renewed attraction.)

I finally got the jetting spot on, but it's still a top end hit bike.

I changed the triples to match the oem 25mm offset to work with the frame and it now turns very well without loss of stability.

The forks were always harsh so I got Gold Valves put in and some tuning. They're now a bit less harsh - an improvement but not the floating feeling of the big zokes on the Husky. Guess that could be down to the era.

The next stop is to try out the Lectron 36mm carb that I'm running on the Husky.

Happy New Year all, have some great riding over the break, if you can get out.

 

[arjay]

Just a quick report. I got the forks and shock working much better with a bit of adjustment. Softened compression on the forks and added rebound to keep the front wheel in the corners. I added compression to the shock and rebound to stop the bouncy feeling at the back. It tracks nice and straight and can be pushed harder in the woods. The big revelation of the ride was how well the new billet clutch perch and lever worked - a Righteous Stunt Clutch, with bearing on the lever and virtually no sideways play (plus lever position adjuster). I could operate it with one finger which is saying something for the old KDX motor! And keep that up for an hour or two. I have big palms and short fingers (Cornish dna) and it worked just fine.

 

[MikeT]

How difficult was it to get the engine to mount up? Did everything line up or did you have to shim things? What was the hardest part of the build?

 

[arjay]

The engine went into the swing arm gap fine without any work, the pivot was the same diameter.
I made up ally triangle mounts to hold the front and get the position right.
The steel tabs on the frame underneath the crankcase needed to be cut and move about 10mm. So pretty painless on the motor.

The harder part was mounting the 89 KX subframe onto the 86 frame. I cut off the existing mounts and got new ones fabricated and welded on. Then the tank had to be built that would match the front of the seat and sit well on the frame.

Nothing too major.

 

[MikeT]

Looks really nice. When I heard you put something other than the '87 KX front forks on it I was greatly relieved. My brother had a '87 KX125 and I had an '88 KX125 and there was a BIG difference on the forks. The '87's were terrible and the '88 was much much better. Since you put '98 Suzuki forks on there they must be light years better.

I always toy with the idea of taking one engine from one bike and putting it on something else. Like putting a 2 cylinder 2-stroke on a light street bike. I would love to do that but have never had the room, money or time. I like that you have been able to make such a really nice bike from top to bottom.

 

[warthog]

Nice bike! I wish they still made nice simple air cooled 2-strokes.