'79 KX250A5 with '79 KDX400 engine fitted ... KX400A5

[Tahitian_Red]

Let me know how those spring rates work out as I haven't ordered springs for the A5 yet. 

[TM BILL]

John that looks great  IMHO it looked wrong with the disc front end ( although i could see your reasons for going that way )

In its current form it looks the dogs bollox  go out and enjoy it 

[Ted]

You best be sending me that one as well. I'll send it back so you go 1. 1 . next time

Looks great buddy.

[John Orchard]

Thanks Guy's  :-)  I tested the bike today, even if I do say so myself, "bloody brilliant ride", aside from the front drum brake, this is possibly one of the best bikes I have ever ridden!  With the pipe cleaned-out, the power is much broader, easy to control with the heavy flywheel.  Probably not the most fire-breathing open-classer but so user friendly. 

Much more comfortable with the rubber handlebar mounts over the rigid mounts of the '84 KX125 front-end that I just took off.

Just waiting on a smaller rear sprocket to land (which may mean I won't have to fit the KX420/500 gearbox) and I will be in heaven  :-)

[Speed]

I knew you would get it right mate. 

[John Orchard]

Tried the 48 tooth Talon sprocket (with 15 tooth front), it made 1st gear of the KDX400 box useable but the gap from first to second and second to third was too great.  Now have all the parts from KX420 & KX500 to go in the gearbox.



Had power loss from overheating, the vents in the front guard seem to have helped, I'll also try some higher octane fuel.

The rubber mounted bars tended to twist too easily, fitting a one-piece bar clamp cap from a later model (KX250F1) has fixed the issue.

[Lozza]

Tried the 48 tooth Talon sprocket (with 15 tooth front), it made 1st gear of the KDX400 box useable but the gap from first to second and second to third was too great.  Now have all the parts from KX420 & KX500 to go in the gearbox.

Run the ratios through Gearing Commander to check your rpm drop each gear change, if your still falling out of band you have to widen the engines effective rpm range.

[John Orchard]

Have set-up a mixture of KX420 & 83 KX500 gears, with a taller first & second.  A KX420 input shaft & gears drops straight in with an 83 KX500 output shaft & gears.  KX500 kick idle gear is 1mm narrower, I will machine the KDX400 kick idle gear to work.

The two free-spinning gears on the ouput shaft of KDX400, KDX420 & KX420 have siezure issues, the KX500 runs same gears as KX420 but uses anti-sieze bushes in the above gears.

[John Orchard]

Anyone with KX125/250A5's will know the problem of constantly breaking sidecover mounts, the vibration from the big-bore makes them break even quicker, I just braced the mount, should fix it.

[John Orchard]

The next mod to combat engine heat, the Pro-Flow scoop, this is a genuine Kawasaki SR380 works item, sourced from Ted's Emporium of rare vmx parts  ;-)







http://www.motocrossactionmag.com/Main/News/MXAS-GYRO-GEARLOOSE-INVENTION-OF-THE-DAY-TRYING-TO-10617.aspx

[John Orchard]

OK Guy's, you can now score this baby, time for a new project, $5900 claims it.

[80-85 husky]

I rode it the other day and its a sweet ride, stunning engine and rides nicely.... pay me later John

[bishboy]

That is nice John and a credit to you, I'd be all over this (saves me from having to do all the hard work  ), but unfortunately I was made redundant a little while ago and am struggling to find something else 

Did you end up changing the gearbox ratios?

[John Orchard]

Yep, it runs a mixture of KX420 and KX500 gears, the KX420 for the good 1st & 2nd ratios and the KX500 output shaft for the anti-seize gears.

[John Orchard]

Comes with good spare KDX400 gearbox. And still has the lighting coil fitted.