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Scott Falcone
Joined: 22 Jul 2009
Posts: 19
Location: United States, Colorado, Lone Tree
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 Posted: Thu Jul 12, 2012 12:50 am Post subject: |
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| Did you check if the power valve gasket is upside down? |
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John Savage
Joined: 30 Jan 2002
Posts: 1252
Location: United Kingdom (Great Britain), not USA state,
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| Posted: Thu Jul 12, 2012 4:55 am Post subject: |
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| Richard Thoms wrote: | | Are you supposed to measure the float height with the fulcrum just resting on the needle or with the needle compressed to closed position? I've always measured in resting position. |
The position is basically a reference position, so check that the valve is working (procedure in my article above) then check with the lever (fulcrum) just resting on the spring loaded plunger 
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Dellorto, Mikuni and Keihin Jetting & Kart Set-up Software
www.rotaxjetting.com www.kartsetupsoftware.com |
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Robby Mott
Advertiser
Joined: 20 Aug 2001
Posts: 308
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| Posted: Mon Jul 30, 2012 4:48 pm Post subject: |
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| Have you replaced the fuel pump? |
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Eric Alexander
Joined: 19 Jun 2011
Posts: 121
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| Posted: Fri Aug 03, 2012 9:46 am Post subject: |
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Just to follow-up since so many are kindly offering tips. I've replaced the fuel-pumps (rebuild kits) on both karts last summer. RAVE valves were rebuilt (new bellows and springs) start of this summer.
My next time at VIR will be late August. We've broken down both carbs for ultra-sonic cleaning (as we normally do) and when we put them back together we're going to alter float height as mentioned ealier in this thread. I'll follow-up here after we test. |
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Chris McGinley
Joined: 28 Nov 2008
Posts: 358
Location: United States, New Jersey, Sewell
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| Posted: Fri Aug 03, 2012 11:09 am Post subject: |
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| Eric Alexander wrote: | Just to follow-up since so many are kindly offering tips. I've replaced the fuel-pumps (rebuild kits) on both karts last summer. RAVE valves were rebuilt (new bellows and springs) start of this summer.
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Eric,
If you did the fuel pumps *last* summer (as in 2011), I'd highly recommend doing them again, even if it isn't a fix for this particular problem. Pump gas with ethanol is brutal on the pump membranes. I think I've had to rebuild mine 3x this race season alone.
-Chris
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Chris McGinley
Monster Raceworks
Rotax Masters
"Always stay one step ahead of the storm" - JZS
http://www.njkarting.org
http://www.btbsecurity.com |
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Robby Mott
Advertiser
Joined: 20 Aug 2001
Posts: 308
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| Posted: Fri Aug 03, 2012 12:41 pm Post subject: |
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Yeah.........what Chris said.
When I was running Rotax a lot.............I would put a new fuel pump before EACH race. |
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Eric Alexander
Joined: 19 Jun 2011
Posts: 121
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| Posted: Sun Aug 26, 2012 4:32 pm Post subject: |
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I want to follow-up in this thread in case future users come across it in a search.
I finally got the karts back on the track this weekend and we got rid of the issues. We essentially continued to to jet down until the problem was gone. So while the software recommended 160, we ended up running 155 (so we calibrated the software to -7% for our engine/carb combinations). The plugs looked a bit on the lean side, but we never had any back-fire pops letting off the throttle on long straights so we went with it. I have to say as a new rotax karter, I was a bit concerned about leaning things out too much and I didn't feel I knew much about the warning signs. That, plus not really knowing whether to go leaner or richer to resolve the issue. So that sorta kept me from just continually leaning things out during my four previous track days.
Both motors are well into their service life and in need of a rebuild. I'm not sure if thats any reason why we had to jet so much leaner than the software called for. But we logged 60+ laps on both karts today and everything ran smooth with water temps in the normal range.
Thanks to everyone who took time to post in this thread. |
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