KX500 street bike

[misterV]

hiya fellas,
I've got a Cagiva Mito with a 91-92 KX500 motor slotted in... I've had it about a year and its been an ongoing development. Just had the motor rebuilt; new piston, bearings toip and bottom etc,  and looking to get it set up nicely, could do with some help. I used to run it on a Mikuni carb, which had been overbored to 40mm. I think the main jet was something huge like 380. Its running a custom-made pipe by Pete Gibson which obviously has much differnet characteristics to the original pipe. Anyway, I found the Mikuni used to sacrifice low end grunt for top end rush, probably partly due to the characteristics of the chamber. I've got a new Kehin 39PWK flatside which I'd like try and set up as an alternative. Wonder if anyone has any experience or suggestions?

Generally the bike surges quite substatially once the throttle's been chopped, I've read up most the posts on the site and know its a common characteristic of the big motor with the volume of air sucked in, but I'm looking to try and reduce the surging and bucking as much as possible, cos its a real handfull on the road, it only weighs about 100kilos so you can really feel the movement of the motor!

other quick q, what torque should I tighten the head nuts down to now its had a run out? cheers!

[gwcrim]

Man did you get me thinking..... I have an old Suzuki 400 that would be a hoot if there was a 500cc two stroke in it.

Things that make you go HHHmmm......

[demographic]

Man did you get me thinking..... I have an old Suzuki 400 that would be a hoot if there was a 500cc two stroke in it.

Things that make you go HHHmmm......

Pics taken from the thread over on another forum, but it's Voyseis bike



Looks pretty sweet I think

[demographic]

Oh yeah and this is mine, taken a while ago, before I bought the Zipty kit

[mikesmith]

Im trying to imagine the Cagiva with the 500 as far as what itd be like to ride,quick I bet!

[misterV]

Yep the Mito is a real riot to ride!

I got the fuelling sorted - swapped the MIkuni for a new Keihin 39mm flatside then took it up to Road & Track Dyno in Aylesbury (UK) for a dyno-set up. Now its jetted correctly it pulls your arms off on acceleration, so you can imagine its just riding the wave of a big powerband throughout the gears till its off the clock! Rear wheel power is about 50bhp, a little lower due to use of a filter rather than an open carb and 'cos the engine has just been rebuilt. Should show a bit more after break in. As it only weighs about 100kg the thing is like a missile!

Here's a more recent pic:



p.s Demo the KX s.m. looks equally like a blast to ride

[Pinchy]

I had to do a double take on this thread.
I read it and then saw the pictures and said 'ok thats kewl' then went on my way. But I got to thinking didnt really see any kx500 motor and where was the kickstart? I didnt even notice the first time I saw it but it was there as plain as day like some alfalfa sprout hehe;)

Its neat how you managed to get that motor in there and have the kick usable without butchering the fairing. How about some pics with it all exposed?

 Ive always loved the idea of putting motors in different frames. Maybe someday I can build that gsxr1100 in a xr600 frame like I saw in some old motocross mag years ago. Does anyone remember that issue? It had that and a 800cc 2 stroke maico and some 2 cylinder 2 stroke husky that looked badass, I think it was in the range of 800cc or so too. They also mentioned someone entered like some 600cc ninja with supsension mods into the BAJA race and actaully finished[of course not high ranking but finished unlike many bonified dirt bike contenders].

[mikesmith]

That was in Dirt Bike (GSXR),heard of a Harley in the Baja (DNF) but not a Ninja.

[misterV]

Sure here's a pic of the engine - nice and easy access for plug chops eh?


the kickstart is probably the biggest giveaway there's something else lurking under that bodywork - well that and the sound when shes running! brang tang tang! Suppose the other big giveaway is the wild acceleration!

[demographic]

Sure here's a pic of the engine - nice and easy access for plug chops eh?


the kickstart is probably the biggest giveaway there's something else lurking under that bodywork - well that and the sound when shes running! brang tang tang! Suppose the other big giveaway is the wild acceleration!

demographic searches deep in his pockets for Cagiva Mito money, finds one pound twenty three and gets a can of beer to console himself

[91kx]

Ther's enough room in their for a beer and a couple sandwiches!

[orderofsion]

this is my kx5 powered road bike . i've not weighed it properly but it feels just a little heavier than my vespa 50 so its probably about 80-90kg . when the crap picture was taken the silencer and rear hugger were off for further modification but otherwise thats it in daytime road spec . it is without a doubt the fastest bike i have ever ridden and it scares the hell out of me , last week whilst riding in the rain i got a MASSIVE wheelspin in third at about 70mph (ok 65-70) as the power cut in and thats with a v/soft compound tyre . the improved geometry and weight distribution mean that it will out accelerate a motocross kx easily once upto 30mph (as full power is just about usable and reachable) and will pull to about 130 mph (200kph?) . the next bike will have a maico 620 engine which is meant to produce about 75hp , from the kx's 55hp to the maico's 75hp !!!

[misterV]

Superb! I love the stripped down look of your machine - no wonder it weighs so little and goes like crazy. Have you got any better pics - I'd love to see a bit more clearly what you've done. If I pull the fairings off mine its much the same there's really not much else to it!

I know what you mean about wheelspin - I ride mine in the wet and it can be a problem to get the power down - I've calmed things down with the gearing, which makes it a bit less manic on the road and helps keep the front down.

Tell us a bit more about the chassis and parts you've used? I think getting the motor as far up front as possible helps. The mito frame is designed around their old 500GP bike so the handling is bang on. 200kph sounds about right, mine will reach that, then its off the clock - its bloody frightening at that speed though on a tuned two stroke single...

good work!

The maico engine sounds even more mental. I'm thinking about another mito with a bored 350YVPS (350RZ) motor which should nudge 70bhp.

[doordie]

Guys!

Do I heard right, swap engine to a Yamaha or whatever to reach more than 55bhp?

1.Easy to get 60 bhp.
2.Little Money and little skill to get 65 bhp.
3.Little more Money and SKILL to get 70 bhp.

And you still got right brand of engine and money left to buy "fancy stickers".

//doordie

[orderofsion]

Hi ,I'm glad you like the bike , I think that some people find the very naked look a bit too different . I have a couple of other photos but they were all taken in the woods and the dappled shade makes it hard to see anything but I'll try to get them on the site . I've also got a picture of the bike in its previous incarnation with an ally frame which I will put on but right now I'm using a friends computer so I dont have access to the photos. The frame is made from high quality steel to my own design , its not he lightest but I was prepared to sacrifice a few kilos for greater stiffness , as it happens the steering head has either been welded on incorrectly or I got my choice of geometry wrong as the steering is way to slow but at least it dont tank slap ! Without checking my notes I think that I went for 25.5' and 93mm of trail so it should have been ok. On the front we have rgv250 usd forks and front wheel with a larger 300mm rgv125 disc and a 6 pot caliper from a tl1000 , it all went together first time with no mods.The bike can easily be stopped with one finger in the shortest of time using only a few degrees of lever travel . The rear is a mix of cbr6 wheel , ns400 swingarm (from the origional bike that it all started with) , malaguti rear caliper with my favourite bit the invisable caliper mount and the rear shock is from an aprilia rs250 with 3 way adjustment. The suspension needs setting up for the new machine the front forks especially are way over sprung and damped.The exhaust is from a ktm550 and works very well , I'm just working on a new homemade silencer that will be ultra thin and tucked up under the seat bearly visable. Then of course there are the thousand and one hidden little things , the 15 different types of gear linkage I had to go through , the innumereble seats and silencers that failed. Putting the engine forward has helped keep the front wheel down but only at the expense of extra wheelspin  which I quite like , I'm running the bike on 16/33 sprockets and a 140/70/17 tyre which I think gives me 18mph/1000rpm and I'm realy tempted to get a larger rear sprocket , maybe 40 teeth that'll spin up lovely . I've got to admit I'm a bit jealous of your bike , mainly for the fact that everything will work properly it will feel like an proper bike but with a thumping engine , I get the feeling that mine will always feel like a homemade bike but then again it gets better with every new modification now how can I sharpen the steering up ?