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Benn Herr
Joined: 18 Jul 2001
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Jimmy McNeil
Joined: 12 Apr 2006
Posts: 1478
Location: United States, California, visalia
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 Posted: Tue Jan 15, 2013 11:25 pm Post subject: |
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How do you know what size to drill it to. Does the pressure from the pump stay the same no matter the engine rpm? Does the pump psi increase or decrease with engine rpm?
I thought with this low pressure pump you didn't need to change the needle valve. What if you change it and it doesn't allow adequate fuel supply at high rpm?
If I had a pump around set up, I would go with that. Seems safer |
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Matt Dixon
Joined: 21 May 2007
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Location: United States, California, Norcal
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| Posted: Tue Jan 15, 2013 11:48 pm Post subject: |
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It seems like after trying and buying all these options plus factoring in the $ and time at the track trying to fix the problem and figure it out. $400 for a proven fuel system that works flawless for the 125 newbie or for Fritz and Jimmy is well worth it.
Then again some just like to figure things out for themselves and don't mind the frustration of not running right.
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Chris Reinhardt
Joined: 29 Aug 2002
Posts: 2951
Location: United States, New York, Ossining
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| Posted: Wed Jan 16, 2013 5:34 am Post subject: |
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| Jimmy McNeil wrote: | | How do you know what size to drill it to. |
You wait till it goes SQUEAK!!!! Then open it up one.... 
The smaller seat works well, we used that on the 450 superkart without an issue.....
There's a 100 ways to slice it, depends on how much time and money you want to spend....
CR
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Mike Goebel
Joined: 28 Jul 2001
Posts: 5794
Location: United States, California, Winnetka
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| Posted: Wed Jan 16, 2013 7:04 am Post subject: |
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| Matt Dixon wrote: | | It seems like after trying and buying all these options plus factoring in the $ and time at the track trying to fix the problem and figure it out. $400 for a proven fuel system that works flawless for the 125 newbie or for Fritz and Jimmy is well worth it. |
A $400 fuel pump is about 10% of the cost of the total engine 
Mike G.
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Chris Reinhardt
Joined: 29 Aug 2002
Posts: 2951
Location: United States, New York, Ossining
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| Posted: Wed Jan 16, 2013 7:45 am Post subject: |
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| Mike Goebel wrote: |
A $400 fuel pump is about 10% of the cost of the total engine
Mike G. |
RLV Pipe kit with mount and silencer is about 15% of the whole motor kit.
We at about 1/4 of the cost the motor and we haven't touched any Honda Parts yet 
CR
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Todd Kageals
Joined: 15 Jun 2012
Posts: 271
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| Posted: Wed Jan 16, 2013 5:12 pm Post subject: |
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| Chris Reinhardt wrote: | | Mike Goebel wrote: |
A $400 fuel pump is about 10% of the cost of the total engine
Mike G. |
RLV Pipe kit with mount and silencer is about 15% of the whole motor kit.
We at about 1/4 of the cost the motor and we haven't touched any Honda Parts yet
CR |
Yeah....no joke....the expense of all the accessories to put together a "roller" I bought has been shocking
But back to my issue
If I use the smaller seat, what size would your recommend. I've checked the float level and it's right at 16mm (that's the spec. for the pwk). If the smaller seat can supply enough fuel for the 450, I'd think it would be OK for the 125 too. Do you just use the stock needle and a different size seat or do you have to get a different "needle" too? |
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Jimmy McNeil
Joined: 12 Apr 2006
Posts: 1478
Location: United States, California, visalia
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| Posted: Wed Jan 16, 2013 6:16 pm Post subject: |
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If you change the needle valve, will the low psi Dellorto pump produce enough pressure?
I had one carb with the different needle valve and ran it with a round Mikuni pump. |
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Sam Zavaglia
Joined: 23 Nov 2004
Posts: 1194
Location: Australia, Sydney,
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| Posted: Wed Jan 16, 2013 6:32 pm Post subject: |
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This topic is so confusing with too many options and problems, I'm taking all my pumps walking out of here.
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Chris Reinhardt
Joined: 29 Aug 2002
Posts: 2951
Location: United States, New York, Ossining
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| Posted: Wed Jan 16, 2013 6:59 pm Post subject: |
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I ran stock CRF450 carb (Keihin FCR) or a Mikuni HSR, both had removable seats and a recommended seat for gravity feed, and a recommended seat for fuel pump feed.
From the 125, if my memory serves me well, I think we had a 1.7 or 1.8 seat.
We used Mikuni DF52 pumps on everything...
If you haven't figured it out yet, a fuel system that works 100% time and jets correctly, all the way through is the biggest PIA with these karts.
We fooled around with different systems, and they all worked to a degree, but none worked 100% of the time the way we liked. Then we cracked out the credit card and bought the hot setup at the time, the double pumper, that work 100 times better nearly all the time.
You're going to have to experiment, or go with something proven...
Good luck..
CR
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Todd Kageals
Joined: 15 Jun 2012
Posts: 271
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| Posted: Wed Jan 16, 2013 7:51 pm Post subject: |
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| Jimmy McNeil wrote: | If you change the needle valve, will the low psi Dellorto pump produce enough pressure?
I had one carb with the different needle valve and ran it with a round Mikuni pump. |
Yeah....good point. Benn said I will need to use one of the other higher flowing pulse pums (round or square mikuni). He also believe that moving the Dellorto lower should work with the stock Keihin so I am going to try that first. Steve's pump is lower than mine too so I will try that and let everyone know how it goes. |
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Todd Kageals
Joined: 15 Jun 2012
Posts: 271
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| Posted: Wed Jan 16, 2013 7:59 pm Post subject: |
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| Oh....it's not the money (what's another $200 at this point ) I was just hoping to find a simple, clean, low maintenace way to get fuel to the carburetor. The Dellorto in its current location LOOKS great....too bad it doesn't work! |
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Chris Reinhardt
Joined: 29 Aug 2002
Posts: 2951
Location: United States, New York, Ossining
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| Posted: Wed Jan 16, 2013 8:29 pm Post subject: |
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| Todd Kageals wrote: | | Oh....it's not the money (what's another $200 at this point ) I was just hoping to find a simple, clean, low maintenace way to get fuel to the carburetor. The Dellorto in its current location LOOKS great....too bad it doesn't work! |
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East Coast Super Kart Series
"This is how we roll!"
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www.CR2MotorSports.webs.com |
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Benn Herr
Joined: 18 Jul 2001
Posts: 1584
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| Posted: Wed Jan 16, 2013 8:30 pm Post subject: |
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While the small inlet seat should be able to deal with the lower regulated pressure from the Dellorto pump, I would recommend using a non-regulated pump. The needle opens from the drop of the fuel level in the float chamber, it doesn't have to be pushed open like a diaphragm carb does. You would get a quicker "refill" with the non-regulated pumps.
Some have wondered about the ability to supply fuel through a hole that is close to the same size as their main jet. It's not a problem. The fuel pressure to the inlet seat is typically around 2 psi (around 55.4 inches of water) and pretty continuous. Fuel is only drawn through the main jet when air flows into the engine, about 60 percent of the time. The differential pressure between the carb bore and the float chamber is not very great at wide open throttle when the demand is greatest. I'd estimate the the small inlet seat has 3 to 4 times the capacity required compared to how much the fuel can be draw through the main jet by the engine.
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Chris Laird
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