Carb and fuel system

Sam Zavaglia · Posted: Tue Nov 27, 2012 10:50 pm Post subject:

HAHAHA, your very quick you smartass. Laughing

Alex King · Posted: Wed Nov 28, 2012 12:58 pm Post subject:

Is Goebel looking to become Australia's #1 non-profit engine builder?

Alex King · Posted: Wed Nov 28, 2012 1:03 pm Post subject:

Sam - I just sent you an introductory email to MRC...get in touch w/ them and they will make your life easier. Maybe you can become a MRC distributor in Australia...they are more than just an engine builder.

Joshua Stanford · Joined: 17 May 2010 Posts: 11

So does mounting the fuel pump next to the gas tank with a long pulse tube make the engine run better overall ? does that system only work with a non-pump around system ? im trying to find a better way to have my fuel set up so I wont have to give in to the hype and get the swedtech system Sad

Steve Buckner · Joined: 22 Apr 2003 Posts: 839

Chris Reinhardt · Posted: Sat Dec 08, 2012 7:06 am Post subject:

Alex King · Posted: Sat Dec 08, 2012 11:25 am Post subject:

Not sure about performance but it will certainly make things look cleaner/better. All you need is a bracket/mount from MRC. Reach out to your shop of choice as they may already be or will soon become a MRC dealer. If not, just reach out to 2Wild Karting and they can certainly help you with this MRC set up. And while you are at it, get the MRC mount/bracket for CDI Box & Coil.

Ryon Beachner · Advertiser Joined: 26 Mar 2007 Posts: 344

Before everyone tries to over think this, the reason MRC mounts the fuel pump on the gas tank is to keep it away from the vibration of the engine that can often break the tabs off the fuel pump.

Mounting the fuel pump below the engine can result in oil vapor pooling from the crankcase and heading towards the pump and impeding its operation, to solve this they run a Y in the pulse to route the oil into a "trap".
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Alex King · Posted: Sat Dec 08, 2012 12:53 pm Post subject:

See...told you that 2Wild Karting could help you...just give them a call and you are set...trouble free...and go have some great fun!

Joshua Stanford · Joined: 17 May 2010 Posts: 11

thanks for all the great info but can some one link me the mrc stuff cause I cant find it on 2wildkarts website

Sam Zavaglia · Posted: Sun Dec 09, 2012 5:33 pm Post subject:

Seems I have sorted the problem out for me anyway. Wink

The PWM 38mm brand new out of the box has the float level set at it highest point, meaning that it closes the needle/seat just before the carb's bowl is completely full, almost to the brass bowl overflow tube. Lowering the float level a little will provide enough force against the standard needle/seat to keep it shut tight before the bowl fills enough to overflow through the brass bowl overflow tube. This will work with the round Mikuni or Dellorto pump.

I found that the Dellorto pump still has enough pressure to blow off the PWM set at factory float height (even with it's internal bypass) and spill through the overflow tube, (maybe not as much as round Mikuni) but still does it even with a "T" returned to tank from the output of Dellorto pump like in this setup.

Having the external bowl overflow hose facing upwards (As mentioned here http://www.swedetechracing.com/news-events-blog/wp-content/uploads/2012/10/pwk-vent-single-pump-2.jpg)

would just mean that if/when the bowl gets too full it will then overflow through the carb throat making the engine richer and slower especially out of the turns, hence why the SwedeTech GFS setup claim better engine response over this type of setup. The external bowl overflow tube should never be pointed back higher than the entrance to the internal bowl overflow tube itself, otherwise it defeats it's purpose of the overflow tube to begin with. Only the side/top breather tubes should go up and over the carb.

Chris R,
I understand the concern for mounting the pump lower than the manifold pulse line. This is where I mount my fuel pump.

I have 6 engines out there all mounted the same for min of 12 months. The oldest engine mounted there for 3 years, at least 12 times on the track per year, so help me god if I have ever opened or even unbolted the fuel pump to clean it out any oil build up. Works perfectly every time.....but I do understand your concern mounted there. (yes the engine bottom end never touched in that time, including the pump, it's still on it's original crank installed new from Shark engine package) but it's time to replace crank over Christmas. BTW, ELF HTX-976 oil, 20:1 ratio using 110 octane leaded fuel.

So my preferred setup is round Mikuni, 1 fuel out to carb, one fuel out to tank, lower the std PWM38 float level a touch and watch your engine sing out of the corners with no overflow out of the bowl tube.

Carb setup like this.

2 top vents joined to each other = sealed closed.
2 side vents going up and over carb = 2 vent tubes is all that's required.
Bottom bowl overflow goes straight down into a catch bottle.
So that is only 3 lines going down plus your gearbox breather.

This is my setup that I share with you to help everyone enjoy their racing as cost effective as possible. Please don't attack me if anything you don't agree.

Cheers,

Sam
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Joshua Stanford · Joined: 17 May 2010 Posts: 11

thanks sam for all that info ! I will mount my fuel pump like yours it looks so simple and clean !

Sam Zavaglia · Posted: Sun Dec 09, 2012 6:25 pm Post subject:

To get the pump orientation right, you have to turn the body 2 positions like this.

Also make a mounting bracket like this.

In my last pump mounts I made the bit which it holds onto the engine slightly longer and then drilled a 10mm hole, use a M10 x 100mm long bolt through the entire engine cases where the original bike engine mount would attach. This makes this bracket a bit more stronger and can tighten it up harder. You can make out what I'm saying on the black kart above. Wink

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Steve Buckner · Joined: 22 Apr 2003 Posts: 839

Great Job posting pics and info Sam. Clean chite dude. Cool

Robert Daniel · Joined: 26 Oct 2008 Posts: 119

Where did you get the stator cover? Any problems with heat in the electronics?
Thanks,
Rob