Hey Jesse...KX153 progress!

newmann
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newmann
Edited Date/Time 1/26/2012 11:27pm
It is 153, correct? Got the 250 F radiators butchered up , shortened and fit in place with all the outlets going the right directions. Sending them off to PWR to have a set custom built. Fitting a KX250 kickstarter on it as there is no way the 125 kicker will fit without having a pipe hand built. Carb and airbox issues coming up next.







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pitbike502
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pitbike502 10/30/2009 8:03am
10/30/2009 8:03am
that looks pretty cool. isnt it going to be heavier than the steel frame though?
newmann
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newmann 10/30/2009 8:20am
10/30/2009 8:20am
pitbike502 wrote:
that looks pretty cool. isnt it going to be heavier than the steel frame though?
Go read the 2010 YZ450 threads. Weight doesn't matter. It doesn't matter how heavy it is putting it up on the stand, only how it feels on the track. I took probably a dozen pounds off the top of the engine by going from 4 stroke to 2 stroke. Yamaha's "mass centralization" doesn't have shit on mine. LOL ! Just kidding....It's just a project bike, wanted something different and definitely not 4 stroke. I honestly have no idea if it will be heavier than the steel frame but wouldn't expect it to be much lighter.
pitbike502
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pitbike502 10/30/2009 8:26am
10/30/2009 8:26am
I just figured that since the frame had to be larger to accomadate the 4 stroke, it would almost be overkill for the "little engine that could"

The Shop

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BUTCH
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BUTCH 10/30/2009 8:32am
10/30/2009 8:32am
Cool project, nice job!
crf250pilot
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crf250pilot 10/30/2009 8:35am
10/30/2009 8:35am
Be careful or you'll kick the piston right through the spark plug with all that leverage
WORCSRacer
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WORCSRacer 10/30/2009 8:41am
10/30/2009 8:41am
crf250pilot wrote:
Be careful or you'll kick the piston right through the spark plug with all that leverage
He should think of it as a handcrank...
dl117
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dl117 10/30/2009 9:12am
10/30/2009 9:12am
That thing is coming along nicely. I recently found a rmz450 roller that i want to stuff my 250 2stroke into.
newmann
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newmann 10/30/2009 3:30pm
10/30/2009 3:30pm
Big Lenny wrote:
Newmann, you are the man...
Don't know about that, we'll talk as soon as I figure out this airboot situation...............Aaaaaarrrrrrrrggggggghhhhhhhhhhhhhhhhhhh! Got a 125 and a 250F airboot butchered up trying to figure how to mate them. Fortunately for me 3M makes some black shit that works for just about anything. It's my "go to " glue!
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J.F.S 10/30/2009 3:32pm
10/30/2009 3:32pm
Awesome project Newmann, that is so cool!
williamsmotowerx 10/30/2009 3:44pm
10/30/2009 3:44pm Edited Date/Time 4/17/2016 6:42pm
Nice Joe!

I don't think I told you... but the stock jetting is a great place to start with that motor... should be very, very close.

It's a 58mm bore, 56.5mm stroke. The KX125's you can't stroke that much without getting into case issues. I'll have to figure out what the exact CC's end up being.
ASH510
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ASH510 10/30/2009 3:58pm
10/30/2009 3:58pm
hows reliability on the motor gonna be compaired to a stock motor
williamsmotowerx 10/30/2009 4:03pm
10/30/2009 4:03pm
Very little difference... If the stock crank is good for 100 hours, this is good for 95.

And these figures are just for arguments sake, every rider is different. The owner takes care of it like he would his stock bike.

You start out with race gas and ween it down after you get comfortable with settings and environment.
newmann
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newmann 10/30/2009 4:07pm
10/30/2009 4:07pm
williamsmotowerx wrote:
Nice Joe! I don't think I told you... but the stock jetting is a great place to start with that motor... should be very, very close...
Nice Joe!

I don't think I told you... but the stock jetting is a great place to start with that motor... should be very, very close.

It's a 58mm bore, 56.5mm stroke. The KX125's you can't stroke that much without getting into case issues. I'll have to figure out what the exact CC's end up being.
Since we started with just a core engine, I never had a stock carb. I thought I told you we had this big chunk of blinging PSI Big Air carb? You ever have any experience with these on two strokes? Thought I'd give it a try. For the most part, everything is externally adjustable.

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roost251 10/30/2009 4:14pm
10/30/2009 4:14pm

awesome, for the airboot you mave have to mate a billet plate too match the different patterns. Look at bannedcr500riders.com and cr500riders.com on the AF sections, not kx's but the airbox conversion stuff is somewhat universal, also differnt year airboots may work a little better than the one you have now.
williamsmotowerx 10/30/2009 4:15pm
10/30/2009 4:15pm
I actually have a bunch of needles for that thing! The needle controls everything, hopefully I still have some notes.

I helped dial those carbs in when he first came up with them... but that's a long story I won't get into on the web. We'll talk about it on the phone someday.

Did the bike run good with that carb on there stock, or did you even get a chance to try it?

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newmann
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newmann 10/30/2009 4:17pm
10/30/2009 4:17pm
Never ran either of them. Bought the engine off Ebay.
TerryB
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TerryB 10/30/2009 6:40pm
10/30/2009 6:40pm
I was always intrigued with the PSI carb, and wanted to try one. Please keep us informed on the progress.

Any intention of dyno'ing it when you are done?
KMC440
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KMC440 10/30/2009 8:11pm
10/30/2009 8:11pm
Still drive by PSI's old building out on hwy22 north of Wautoma. Pretty intriguing carb they made.
CamP
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CamP 10/30/2009 8:48pm
10/30/2009 8:48pm
Does that PSI carb work like an old Lectron?
TerryB
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TerryB 10/31/2009 6:28am
10/31/2009 6:28am
Didn't Kyle Lewis run a PSI carb for a season or two, before the switch to 4-strokes?

I had a PSI pipe on my '84 KX125.

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