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Help out w/Powerjet ?'s

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KXcam22:
Hillclimber,
  With a few electrical tests and some thinking, we could probably get that PJ to work.

1. On a PJ KX250, unplug the PJ and measure the voltage that goes to the PJ connector and when (at what RPM) the voltage turns on and off.  verify if its AC or DC.
2.  Measure the KDX200 lighting coil voltage (again AC and DC) and chart it at several RPMs up to wide open.

What I am thinking is that it may be possible to add some simple electronic circuity so that the KDX voltage will increase to the value that will turn the PJ on at close to the right RPM.  It won't be perfect but may work not bad.  It is my understanding that the PJ opens at WOT to richen the jetting for max HP.  From jennings theory extra rich at WOT gives max HP but then then the bike suffers as too rich below WOT - the PJ was invented specifically to get around this. This is backwards to what Doldguy has posted.  Am I backwards? Cam.

The Flyin Hawaiian:
The powerjet coil on the PJ equipped KXs puts out around 25w. I run my lights off of it on my 03,04 KX250s.

Hillclimb#42:
Well, I got some info from Don46, like suggested, and he pointed out that too big of a carb for the application, (like the Cr500 carb) will add top end, but will lose bottom. And thats what happened. He told me that the Kehin was a far better carb than the stock mikuni. The problem that we are missing is that the old lighting coil is analog and the newer Powervalve is a Digital signal. Thats why I ask people on here. Thanks Don.
 I see the test for the Powervalve in the clymer, but its unclear of the power difference. Sounds like the carb will work well without the Powervalve hooked up.
 The magneto from a newer 250 will run a light? Hmmm. Thats what I thought too KxCam22, "it just opens up at max rpm's", but the tests suggest that it gets a steady increase in voltage relative to the rise in rpm's. 12v-15v
  This is a spare carb from the caravan. The 250 originally using the Powerjet Carb upgraded to a Lectron. If I buy a new Carb, it would be a Sudco for the Kx500, but am just trying to work with what I have available so far.
Thanks for the replies,

DoldGuy:
#42,
The powerjet circuit solenoid is in an open position at all times until it gets a signal from the CDI to close at about 8500 rpm (if memory serves me) to lean out the motor producing a hotter Exhaust Gas which in turn speeds up the reflection wave in the pipe allowing the short circuited charge time to be stuffed back in the cylinder before the piston closes the exhaust. If you notice the heighth of the dump tube of the PJ it is set at approx 1/2 slide height (midrange) and that is where most motors have the biggest load & needs the most fuel. If you are currently using a lectron (PJ installed?) start the motor & watch the PJ fuel line to see the fuel start moving at about 1/2 throttle as it uses the same principal. I would think (?) a tuned 200 would take a 38mm carb as I use a 39 on a 125 (& yes it has NO bottom, Great mid & top) that is used for drags, but maybe you guys need a much broader power spread. Another good thing about the PJ PWK is that you have an additional jetting capability with the PJ (has it's own jet) circuit eve with out it hooked up electronically. Hope  some of this helps out in using what you have.

don46:
If you wanted to go to a bigger carb look for one off a 98-99 kx 125 they were good carbs and only 36mm should work pretty good on you kdx.  As Doldguy says you can use the big carb on the 125, in fact the 93, and 94  (I think) came with 38mm carbs, the things ripped. for your application and the bike I think a 38 is to big. For hillclimbing I think a good running kx 125 would kill the kdx 200, the 200 has tons of torque but is much slower getting to peak speed, is there a reason you chose the 200 over say a 125? is it a class specifically for the 200?

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