KTM 250 "Superkart" in a way.. on dirt..

Ken Olson · Last edited by Ken Olson on Thu Dec 13, 2012 7:48 am, edited 5 times in total

Hope not to Offend you "Superkart" guys with our UAS 250 Oval Kart.. fun as ever, and may need some build/tune advice..as these MX bike motors are new to me(usually running our BRC150RR we got from Riley).. way more information here than the other sites for 250's.. which is somewhat tough to find.. any jetting advice would be welcome for a Keihin PWK 36mm.. got it close I think.. may need to richen it up some more as the weather gets colder.. 42 pilot/175 main/clip in the middle and 1.5 turns out on the air screw..
Regards.. Wink

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Ken Olson
Pacific NW Tire Services
Major Racing's "Roll N Prep"
BRC Engineering 150RR

Ken Olson · Posted: Sun Dec 02, 2012 11:17 pm Post subject:

another..

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Ken Olson
Pacific NW Tire Services
Major Racing's "Roll N Prep"
BRC Engineering 150RR

Ken Olson · Posted: Sun Dec 02, 2012 11:32 pm Post subject:

at the track.. Friday night practice in Salem, Oregon.. UAS in the Pacific NW with a little video link to the "Pit Kart" http://www.youtube.com/watch?v=-tNHvDosBoM

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Ken Olson
Pacific NW Tire Services
Major Racing's "Roll N Prep"
BRC Engineering 150RR

Sam Moss · Joined: 28 Aug 2012 Posts: 16

Well I've seen everything now Exclamation

Motorized pit kart Smile

Looks interesting concept, is it a short circuit dirt chassis? What design difference does it have to the usual coke bottle shape to make it more suited for the ovals?

Ken Olson · Posted: Mon Dec 03, 2012 8:44 am Post subject:

Hi Sam, the chassis is built as an "offset"(Buller Velocity) so we can achieve the usual %'s for oval racing.. Something like 56 Left/46 Nose/60 Cross is close to the norm for this type of racing.. we run it indoors on a 1/10 mile track to as big as a 3/10 outdoor 18° banked WOO track.. this particular chassis has seen over 100ft/sec on the bigger tracks up here in the NW..

Standard rubber for these karts is 8.10 on 10" rims on the RS w/a 6.0 LR on a 8.5" rim and a 4.50 tire on a 6.5" rim on the LF.. looking down the right side of the kart.. the RS tires are offset(RF inboard)about 1.5-2"
Also, the front end has the usual caster/camber settings along with lead forward and aft on either side, including the RR.. LR is adustable for Cross as are both front spindles mounted with heims..

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Ken Olson
Pacific NW Tire Services
Major Racing's "Roll N Prep"
BRC Engineering 150RR

Ken Olson · Posted: Mon Dec 03, 2012 9:33 am Post subject:

Here is a picture to give you a good idea just how far the driver sits to the left in the Chassis.. taken during the build..

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Ken Olson
Pacific NW Tire Services
Major Racing's "Roll N Prep"
BRC Engineering 150RR

Gerry MacNutt · Posted: Mon Dec 03, 2012 9:40 am Post subject:

wow you can make that motor live with that rad placement Shocked

Ken Olson · Posted: Mon Dec 03, 2012 9:46 am Post subject:

Like I said, we are new to the MX stuff.. but temps seem pretty normal for a 10 lap heat/20 lap main.. usually around 135°-145° Does that seem too high? Never overheats.. what are you guys running for temps in the Superkarts with the huge rear mounted radiators?
Advice gladly accepted here..
_________________
Ken Olson
Pacific NW Tire Services
Major Racing's "Roll N Prep"
BRC Engineering 150RR

Benn Herr · Joined: 18 Jul 2001 Posts: 1580

135 to 145 isn't bad, but ten degrees cooler is where our CR250 runs best.

Gerry the radiator is probably okay where it is. You have to remember, on a 10 to 15 second lap they are lifting at least twice per lap to get the kart turned in. Our long straights put us at wide open for long periods of time. The Briggs and KT guys might be able to flat foot it all the way around but when you get some THRUST working for you lifting is important! Shocked

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Benn Herr
Come see our Superkart Build Off @
http://www.lostenduros.com/?page_id=1534
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Kart Design
Chandler, Az.

Ken Olson · Posted: Mon Dec 03, 2012 10:59 am Post subject:

Thanks Benn.. I'll look into building some sort of duct for the rad.. appreciate the info.. The mychron is showing low 130's while we are racing indoors on the short tracks in the winter.. last time out it was in the low 50's, so come Summer I had better figure something out.. maybe an alky carb.. sub-11 second laps at this particular track in Oregon..
_________________
Ken Olson
Pacific NW Tire Services
Major Racing's "Roll N Prep"
BRC Engineering 150RR

Matthew Walker · Joined: 12 Nov 2006 Posts: 67

I love it! I looked at some of your youtube footage with the 150 a while back. I would just about give my left nut to run one of those! Maybe I need to just by a saloon car.....
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Experience is that marvelous thing that lets you recognise a mistake when you make it again!

Ken Olson · Posted: Mon Dec 03, 2012 11:06 pm Post subject:

Thanks Matt, Rileys 150 is one heck of a package.. and there are lot's of them being run now.. mopping up pretty well, anything from wankels to 450's and everything inbetween.. highly recommended.. Twisted Evil

Only reason we are running the KTM package right now, is because Methanol and cold weather racing don't mix for me.. couldn't get enough heat in the motor racing in the winter.. also having a manifold machined up for a single 34mm Mikuni instead of the dual billet alky carbs.. I think we are "needle challenged rednecks" Laughing

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Ken Olson
Pacific NW Tire Services
Major Racing's "Roll N Prep"
BRC Engineering 150RR

Ken Olson · Posted: Thu Dec 06, 2012 8:46 pm Post subject:

Stock jetting on the bike from KTM is 35 pilot/160 main/ middle position on the needle clip and 1.5 turns out on the air screw.. this is with the 36mm PWK quad vent carb.. do you think I need to go as fat as I am because we tend to use the motor a little differently than the bike guys?

Or maybe drop the jetting some to make it more responsive.. running a 42 pilot/175 main/ same clip position and 1.5 turns out on the air screw.. seems to run great and is showing some color after 30 or so laps.. not much.. but some.. thing rips..guess the old saying "plugs are cheaper than pistons" holds true..
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Ken Olson
Pacific NW Tire Services
Major Racing's "Roll N Prep"
BRC Engineering 150RR

Gerry MacNutt · Posted: Thu Dec 06, 2012 9:31 pm Post subject:

Is it an SX motor or XC ? what year? KTM went from 38 to 36mm to make for a better trail riding combo, you need at least a 38 PWK. Reed type and tension has a big effect on what your jetting will be. Hard to tell in the pic but that looks like a gnarly pipe which won't be great for your needs.

Oh and I'm of the idea that the rad should be more to the rear, for no other reason then a hot shower is better with a women then it is while racing Razz

Ken Olson · Posted: Fri Dec 07, 2012 7:27 am Post subject:

Motor is an XC-W/the wide ratio trans.. a 2007 w/V-Force reed cage and carbon reeds.. don't have any idea whether the reeds themself are aftermarket or stock.. and you are close on the pipe.. it's a "Fatty" FMF, but falls off hard with the small carb.. 'bout 9750 rpm it's done.. off the bottom it's stout.. and that's where we take advantage of our fellow racers.. coming off the corner and passing underneath.. been pulling gear off for the track we run, and everytime we do.. it just get's faster.

Some guys are running the "Epic" radiator fairing.. which places the rad.. right in front of you..
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Ken Olson
Pacific NW Tire Services
Major Racing's "Roll N Prep"
BRC Engineering 150RR