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Beta Forum My bike is Beta than yours!

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  #21  
Old 06-10-2015
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Oldscool, Yes, I use the clutch to get the motor over that off idle stutter and what you said about a thicker needle makes sense, now that I think back my Husky WR125/260/360s all exhibited the same trait, only the AE430 didn't because being an automatic it needed more revs on board to engage a gear and move so you were always giving it a decent twist to overcome the initial lag. I had an early GasGas200 and some IT200s that ran clean from idle (from somewhat dodgy memory)
So maybe it's just a 2T thing, I might have an opportunity to have another run on a Freeride 250 tomorrow and see how that compares.
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  #22  
Old 07-10-2015
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Quote:
Originally Posted by Oldscool View Post
Roon

I think you'll find that to reduce the off idle richness when gradually opening the throttle you need a needle with a bigger base diameter. Be aware though that this may create a lean hesitation when the throttle is snapped open to 1/4 from fully closed. This is why pre fuel injected 4t carbs have an accelerator pump, modern 4t are fuel injected and so have a perfect mixture for all situations, theoretically anyway.

Please don't think I'm trying to give riding lessons - does using the clutch to smooth out the power delivery help overcome the issue? I only ask because I lack the coordination and skill to test it myself.

Cheers.
100% on the money.

With the simple PWK/PWM carb it'll be a fine balance of circuits working together to achieve the best response. Too clean at low engine loads and you will run lean and fall flat at higher loads.

You have slide cutaway (and if its notched or not), slide height/idle speed, pilot circuit (jet size and air screw setting), nozzle to needle relationship (may be some tolerance variances), needle diameter and straight section length all working together to try and achieve a good mixture that allows the bike to pull cleanly, respond well when required, and idle. It's no surprise that people struggle to find the perfect setting here.

There will also be differences from bike to bike, even within the same brand. What works for a ktm doesn't neccessarily mean it'll work the same in a beta, as it may not work in a tm, etc. Bore x Stroke is just one variable.
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  #23  
Old 07-10-2015
chris250 chris250 is offline
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Quote:
Originally Posted by Roon View Post
Does having oil injection mean a richer mixture at low throttle openings and change the jetting strategy?
For example the oil injection is said to run at 100+:1 at idle/low throttle openings meaning there is more fuel available to burn than a premix bike running at a typical 50.:1
So would running those same needle/clip and pilot jet settings for a premix bike in an oil injected bike give an overall richer setup?
Or is the difference in available fuel so small that a clip position and/or airscrew adjustment all that is needed to compensate?
Hey Roon,
Maybe disconnect the oil injection and run it on a tank of premix.
See if it makes any difference.

As for jetting, I cant offer much info.
Mine just seems to work. No fiddling required.
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  #24  
Old 07-10-2015
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Originally Posted by chris250 View Post
Hey Roon,
Maybe disconnect the oil injection and run it on a tank of premix.
See if it makes any difference.

As for jetting, I cant offer much info.
Mine just seems to work. No fiddling required.
You're a wise man, Chris - some of us can't help ourselves
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  #25  
Old 07-10-2015
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Fugg it - as I'm used to the NECJ now, I might put the NOZK stocker back in just to see if I'm tripping on needle placebo....
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  #26  
Old 07-10-2015
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And try it with stock 38 pilot jet.
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  #27  
Old 07-10-2015
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Update - absolutely no doubt that back to back, an NECJ offers snappier & cleaner throttle response off idle than an NOZK.

I'm going to get a 38p, too, just for fun..

Roon, just a thought - is there too much throttle free play? I only ask as that would delay fuel supply momentarily while you twist it..
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  #28  
Old 07-10-2015
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Yes, I like my throttle cable freeplay to be at the minimum, I like controls to respond the moment you ask them to...
I rode RedHill this arvo with a couple of culprits and the NEDJ and 38 pilot ran great in the cooler temps and I also broke the golden rule of changing 2 variables as I wound the PV adjuster in mid way (3 turns in from flush/3 turns out from bottomed) before the ride. The bike definitely has a beefier feel to the bottom end and seemed to require less clutch modulation to tackle the endless rock steps, we mostly rode 1st and 2nd gear so hard to tell how the mid range feels, let alone truly getting into the power band. I had a quick swap on a FR 250 and the bottom ends felt quite similar, then had a quick swap to a MY16 RR300 and the 250 is definitely a snappier bike to ride, feels lighter to steer as well
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  #29  
Old 07-10-2015
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Cooler today there than it was on Saturday... too hot for a fat bloke at 33 degrees in the shade. Slurpy machine at 7-11 copped a bit of a workout on way home.
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  #30  
Old 08-10-2015
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Originally Posted by ggchris View Post
Cooler today there than it was on Saturday... too hot for a fat bloke at 33 degrees in the shade. Slurpy machine at 7-11 copped a bit of a workout on way home.
mmmmm, brain freeze....
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