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MC21 and MC28 OEM Base Settings...


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Andy
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MC21 and MC28 OEM Base Settings...

Tue Apr 28, 2015 2:53 pm » Post: #1 » Download Post


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paul g
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Fri May 01, 2015 6:44 pm » Post: #2 » Download Post

That's some handy information Andy, hopefully will give a good reference point to start jetting from.

Can you give us a little more info on the base spec of the set up they are refering to? I presume the SS and SP spec are open carbed, hrc airbox, hrc piped, no oil pump, blanked power jets, hrc kitted carbs? Different ignition/pgm?
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Andy
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Sat May 02, 2015 9:58 pm » Post: #3 » Download Post


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Andy
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Sat May 02, 2015 10:12 pm » Post: #4 » Download Post

paul g wrote:
Can you give us a little more info on the base spec of the set up they are refering to? I presume the SS and SP spec are open carbed, hrc airbox, hrc piped, no oil pump, blanked power jets, hrc kitted carbs? Different ignition/pgm?

SS/SP is pretty much as you mentioned. Open carbs, HRC [NSR-WORLD] carb shield, pre-mix, etc.

Let's see how long it is before the freeloaders steal this! Rolling Eyes
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Yuri
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Sat May 23, 2015 8:34 am » Post: #5 » Download Post

The part numbers for the needles are
16131-NDK-600
16132-NDK-600
16133-NDK-600
I read that thy are the unleaded needles or JHA
Thy are in HRC packets
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Yuri
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Thu Jun 04, 2015 5:21 pm » Post: #6 » Download Post

Here are sum of the jha jet papers
I will look to get it properly copied





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ericandchi
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Power Jet Blanks

Sat Jul 04, 2015 11:40 pm » Post: #7 » Download Post

I thought this was helpful information that Matt at Tyga provided me in a recent email exchange.

=======================================================
You willneed to increase the main jet if you blank the power jets.

Work out the area of the main jet. Keihin jets are marked in metric sizes. A #150 main jet for example is 1.500mm. A #152 is 1.525mm. A #158 is 1.575mm. etc. etc.

The power jets work the same way. A #75 power jet is 0.750mm

So add the two together and you get total flow area.

Say #150 main and #75 power jet.

Main Jet Area = 1.767mm^2

Pwr Jet Area = 0.442mm^2

Total Area = 2.209mm^2

Now work backwards:

Sqrt(2.209 / Pi) x 2

Required main jet = 1.677mm

This corresponds to a #168 main jet, but always err on the safe side and go a size or two bigger than this.
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Yuri
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Wed Jan 20, 2016 2:54 pm » Post: #8 » Download Post

I made a proper pdf of the jha jet kit
https://db.tt/dqqL2o1V
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ericandchi
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Thu Jan 21, 2016 2:31 am » Post: #9 » Download Post

Andy,
Would you be willing to place all of this valuable information in a separate part of the forum. Sort of the way you had it in the past. A reference section that we all know how to get to is much better than having it a thread where wingnuts like myself diluted it with comments like this. Maybe have one thread that serves as a drop box where info gets delivered, then once determined useful it goes in the reference section.
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Nafo

 
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Thu Apr 20, 2017 9:22 am » Post: #10 » Download Post

Have a question,

Why do they delete the oil pump? is it that unreliable at high rpms?

Today, we have better syn oils that are able to give great lubrication right up to 100:1. I run 50:1 in my modified Husqvarna TC250, and so far i have been happy with it.

Would it be necessary to delete the pump, or would i be able to keep it for street use?
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Andy
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Thu Apr 20, 2017 10:18 pm » Post: #11 » Download Post

Never personally had a problem with an oil pump.

I've only seen one (as in "1") with a bad drive shaft in 24 years, and always run a pump because I can't be arsed to carry around a bottle of 2T with me to mix at the filling station.

I think you would be incredibly unlucky to have a pump fail on you. Not saying it can't, or even hasn't happened to someone, but incredibly unlucky if it did.
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