Topic: KX250/550 offroad/streetbike?

[rb550four]

kx250/550 offroad streetbike project? One of our members Matt,did a very original scrambler type project maybe 6 months ago. I liked the idea. There was another member who did a most excellent monoshock  swing arm on his 650 Bobber. I liked that idea. While getting to the bottom of all these extra parts while cleaning the garage up I kept thinking about these two projects. Even ran across a Yamaha dirt bike that I thought could do a cross over with... owner couldn't figure out how much he wanted for it....didn't get it.
  So this week I go to the scrap yard with 2 stoves that crapped out and this followed me home.

Good tires, rims, front forks with massive travel, giant mono shock on elongated swingarm, again , massive travel. The rest of this bike is crap.I'm down to one motorless 550 frame and 2 500 engines to rebuild, I'm thinking, that now is the time to push the limit a tiny bit further. I figure if you can jump one of these dirt bikes 100 feet distance , 30 feet high and it'll take it , no reason why it won't hold up on a  little heavier street bike that will be on unpaved roads. The brakes aren't all what I hoped for but they might work.(I'm still talking myself into this) But how can anyone in their right mind pass up all that travel? Or at least find out if it's worth doing. I can't help but wonder how it might ride. Gotta do it.

Correction on donor bike : 1982 kawasaki KDX 250, not KX as mentioned earlier

[kghost]

I had a KDX 175 (1981) the brakes were ok for what it was but not brilliant by any means.

I'd be a bit concerned by the added weight to the frame....

Perhaps you could beef it up?

[70CB750]

You could find a replacement engine for it close to the original?

[Mcwilliams570]

Cool project I don't think the weight of the engine will be that big of a deal not like your going to jump it over a set of double woops (if you do video please

[rb550four]

Kghost I was a a bit concerned about that extra The extra Honda engine weight on the Kawi suspension brakes and axles but realisticly , I won't be riding it like a twenty year old ( probably) right now I fully expect to keep both wheels on the ground( unrealistic expectations perhaps).
70cb750 I could find another kawi engine easy enough.... but I don't ride Kaws, I ride old Hondas. You know that saying "it is what it is", well why does it have to be? In this case why can't it be" it is what it could have been "? These old machines are a blast that way, produced with dark ages technology as compared with today's standard, it's like being able to go back in time and make the changes that those engineers hadn't even thought of yet.
 Perhaps my description of this plan was vague  ,anyways  the plan is to alter and splice the wanted kawasaki  parts into the 550 Honda frame, not to install a 500 4 banger into a kawasaki frame , just to be clear. So there should be much cutting ,fitting ,welding and such. What fun! Been doing allot of looking at it since it got here, think it's go out to the shop time and see what happens.

[rb550four]

Short break from the shop right now. Removed forks,bearings  from both frames. Knocked out old ball bearing races from the 550, the  Kaw has rollers, the top set is sooo close to fit,it's just a touch smaller, machine shop will have to make up the difference. The bottom bearing looks like a decent fit but goes too deep in the 550 neck could put in a backer up under the race but the length of the 550 neck is shorter the the kaw tree spindle. so I cut the lower bearing hub from the kaw, will cut back the lower neck opening to the correct size to match the Kaw neck then weld and assemble later, not bad so far.
  I'm cutting the rear of the kaw frame in strategic places now leaving a little extra so's I don't come up short, not sure what will be going on with seat mounting  or fenders yet but it has begun.

[kghost]

Well, it sounds entertaining.

I just figured with the rear pro-link set up going the other way would be easier.

[rb550four]

Easier??? What 's that?

[rb550four]

The front end was easy, the back end is proving to be a challenge so far but no prob, cutting, grinding and fitting was in the plan. Might take a day or two to get it the way I want it, but I'll only get the frame done and put it in the corner to finish this winter.
 I snuck this project start in early, it was supposed to happen after the side car camo bike, and the new 550 that is waiting at the theater.But I just couldn't wait .

[Dimitri13]

Why not just put dirtbike suspension with knobby tires on a 550 frame? 70s dirtbike frames were double cradle anyway. Just add a bit of bracing and you're golden.

[rb550four]

Dirt bike suspension is going on the 550 frame, Moto X tires and rims too.

I need an off road 550 really bad.         Why? she asks

Well, because Matt made one and he takes it when he goes fishing.
                                                         But you don't fish. says she.
That's true, so what's your point.


    I still get a peck on the cheek on the way out to the garage even though acceptance doesn't include understanding . Priceless.

[LesterPiglet]

Are you sure that's a KX? Looks like it has a street exhaust.
Also the fact it has a front drum AND Unitrak seems odd.

[rb550four]

Lester, It was an assumption on my part, there is no call tag (model) on it anywheres and I didn't track down the vin # . I  thought, from memory that it is an early KX. I'll track it down later and if I'm wrong I'll correct the tread.

[rb550four]

Thread correction,    1981 or 82 Kawasaki KDX,  not KX, haven't tracked down the serial # to find out which year for sure yet. Good eye Lester. I have to go see what the 10th digit letter is to find out what year it is tomorrow.

[kghost]

That's a KDX.

I had a 1981 model 175. The others are similar. Could be a 200 or a 250.

http://www.kdxgarage.com/kdxmodellist.html

[LesterPiglet]

Original specs.
http://www.motorcyclespecs.co.za/model/kawasaki/kawasaki_kdx250%2080.htm

107kg  !!!

[70CB750]

70cb750 I could find another kawi engine easy enough.... but I don't ride Kaws, I ride old Hondas.

Perfectly valid reason, I will be watching your project closely 

Good luck!

[rb550four]

According to the 10th digit which is a C , the year of this donor KDX is 1982.

[Boomhower]

I have no idea why we do the things we do.
A few things to think about;

The engine you are removing is light. The one you are putting in is heavy. 1/3 of your travel is sag......you are going to have to be creative finding springs to do this.

I bet the axles will be fine if you can get the shock and forks to work.

See if you can get a front disk set up from an 84 kx, the forks are the same and should be an easy fit....a lot better brakes. The rear brakes were pretty good those years.

Keep on posting, take some more pictures for us.

[Mcwilliams570]

Dirt bike suspension is going on the 550 frame, Moto X tires and rims too.

I need an off road 550 really bad.         Why? she asks

Well, because Matt made one and he takes it when he goes fishing.
                                                         But you don't fish. says she.
That's true, so what's your point.


    I still get a peck on the cheek on the way out to the garage even though acceptance doesn't include understanding . Priceless.

I wish I have taken it fishing but still working on it RB. I have been working on that 1964 Vespa alot a little here and there on the 550 will get back to work on it this week.





Not much left to do on it finish the exhaust, paint and a bunch of little stuff. Just ordered cr250 pegs for it gotta get those mounted going to try and fire it up this weekend.

Matt

[rb550four]

I really like that machine Matt. and that Vespa, I've never seen an unhappy looking rider on a Vespa, must be allot of fun to ride.

[apetersonboy]

AWESOME

[rb550four]

Had some time tonight to mock up the swing arm and the forks on the 550 frame.
 Oh no!!! I hate it! Sits way too high, can barely get my leg over it !Can't imagine how slow it will react with this new high center of gravity. I foresee much road rash or worse if this machine gets completed......
  The mock up is a fock up! Although I am a true believer that the factory suspension on a 550 can always be improved, this is not an improvement, it's just dangerous . I though it would look cool- doesn't.
   Sorry folks, I'm going to try exercising some common sense here  and cancel this project before it goes any further.

[rb550four]

That was embarrassing, maybe I should take up fishing.

[seaninc]

We all make a mess sometimes. I'm enjoying the SL350 I picked up, maybe look for one of those?