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Author Topic: Project Clapped out 1998 KX250... what works?  (Read 2896 times)
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sandblaster
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« Reply #30 on: May 10, 2018, 02:54:42 PM »

This Friday at 4 we will have some additional dyno numbers.
I will be posting percentages of increase or decrease depending on what we find.
Why not HP numbers?
On two different dyno's we recorded a variance of 19% which is not unusual so, how do we know what is correct?
However, each dyno should show the % correctly of increase or decrease accurately.
Just to tickle you the low dyno said 37hp at the rear wheel. The owner of this dyno said it would be low.
The high dyno said 43hp at the rear wheel.
That was on a worn out top end with no Turbo crank.
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The four stroke engine: That's one stroke for producing power and three for wearing the engine out.
umberto
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« Reply #31 on: May 10, 2018, 03:01:58 PM »

Thatís pretty stout for a worn out motor.  shocked
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Perhaps I have a dirt bike addiction?

03 KX 250/88 KX 525 - Goliath
2017 KX250F/2004 KX250
04 KX 250 - Lunchbox's Bike
05 KX 125/144
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« Reply #32 on: May 10, 2018, 03:10:24 PM »

Yeah, it ran pretty good when I last rode it about 6 years ago...
No brakes though... scary...
Ok, ok, they worked but not at a level that I was comfortable with  shocked
I found myself saying whooooooaaaaaa... too many times that day..
But this is just the start... We have a lot planned for this bike....
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The four stroke engine: That's one stroke for producing power and three for wearing the engine out.
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« Reply #33 on: May 12, 2018, 01:13:16 PM »

Oscar Cota mentioned on FB yesterday that it was a big day for all the guys here at KX Guru Racing. And it's true,,, but not just for us.. Steve Parris has been working with us for a year and a half to get us a Turbo Crank, get it installed, and ran on a dyno. But before I get into all the details let me say to you Steve, everything you told us about your Turbo crank was spot on. It did everything you said. After all these years of having some people say that it does not work, making fun of it, and being down right foolish about it, we have our first bit of proof that it does work. Yes, read it again... IT WORKS!!! IF you ran a turbo crank in the past and showed little to no gains then you did not run one of Steve's cranks.
For a recap for those that may have missed it, we took Jason Tanner's clapped out 98 kx250 and ran it on two separate dyno's. Then we rebuilt the bottom end with Steve's Turbo crank and reinstalled the worn out top end. . We had to rejet due to how the turbo crank works... Then today we stuck it on one of the dyno's and made several runs.... We recorded a 15% increase in power... 15 %........ I think once we get the jetting spot on we might be able to squeeze closer to 20%. Hopefully we will get in next week to the second dyno for validation.... More will be forthcoming as we post more info and get further proof... But as of right now, I know it works... Very impressive Steve.....

I know it was a little premature but we have a Turbo Crank in Jeff Grawbargers drag bike.
We should have some numbers on it very very soon..



Here is the only mod made to the cases... It's mandatory or the Turbo Crank just won't work.





I still think we need to lean out the needle a tad and the main jet one jet size. We just didn't have the time as the owner was trying to close on a busy Friday... When we take the bike to Dyno #2 we should have that done and ready to test so it will be interesting..
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« Reply #34 on: May 13, 2018, 04:34:32 PM »

15-20% is an insane amount more power. That's a pretty exciting Mod.
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« Reply #35 on: May 13, 2018, 06:59:32 PM »

Well... We have 15% right now. But looking at the dyno charts we need to lean the midrange a bit and the top end.
We are running it on a second dyno later this week to verify the first dyno numbers.
I'm betting we will get it to between 17-18%
But remember... this is very early in our testing.
We are going to be using different heads, pipes, and port mods to see what we can get out of it.

Also, sometime this month we are going to put Brute's old KX500 on the dyno and see what it pulls.
It is completely stock.
Then we will do the turbo crank mod to it and see how it reacts.
Remember, KX500's don't respond to crank mods as well as the smaller bikes do.

The cost of a Turbo crank is 350 plus shipping... Figure about another 50 there and back if you insure it through USPS.
So it is not a cheap mod but if your doing your crank anyway you might as well do it.... IF it pans out for the 500.
I'm hopeful but we won't know till we know...
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The four stroke engine: That's one stroke for producing power and three for wearing the engine out.
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