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HereToGo
Samba Member
Joined: April 17, 2001
Posts: 143
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 Posted: Fri May 27, 2016 2:40 pm Post subject: 40 IDF Unresponsive |
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Need some expert advice regarding my 40 IDF setup. Engine is a 1904/100cam/stock size valves.
• Cylinder #1 is not responding to any mixture inputs
• Idle jets are all clear
• Idle circuits are clean and cleared out
• No vacuum leaks at either carb base or manifold
• Getting a constant popping out of the exhaust (no leaks at any joints)
• Swapping plugs and wires (1& 2) makes no difference
Carbs have been thoroughly disassembled and soaked with rebuilt gaskets all over.
Is there anything I might have overlooked?
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Derek Cobb
Annoying
Joined: March 11, 2004
Posts: 2565
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| Posted: Fri May 27, 2016 4:28 pm Post subject: Re: 40 IDF Unresponsive |
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| Leaky throttle shaft? |
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stan_tichomirov
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Joined: May 24, 2005
Posts: 1719
Location: San Francisco, CA
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| Posted: Fri May 27, 2016 4:46 pm Post subject: Re: 40 IDF Unresponsive |
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Choke plunger missing or stuck open?
Stan
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sled
Samba Member
Joined: February 16, 2005
Posts: 6363
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| Posted: Fri May 27, 2016 5:26 pm Post subject: Re: 40 IDF Unresponsive |
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| stan_tichomirov wrote: |
Choke plunger missing or stuck open?
Stan |
Yup, that's what it was on my 40 idfs.
If you flip the carb over you can see the enrichment circuit port, I drilled and tapped it and ran some allen set screws to stop any future leaking
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HereToGo
Samba Member
Joined: April 17, 2001
Posts: 143
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| Posted: Fri May 27, 2016 6:01 pm Post subject: Re: 40 IDF Unresponsive |
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| sled wrote: |
| stan_tichomirov wrote: |
Choke plunger missing or stuck open?
Stan |
Yup, that's what it was on my 40 idfs.
If you flip the carb over you can see the enrichment circuit port, I drilled and tapped it and ran some allen set screws to stop any future leaking |
I'll check on that, thanks. |
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HereToGo
Samba Member
Joined: April 17, 2001
Posts: 143
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| Posted: Fri Jun 03, 2016 11:43 am Post subject: Re: 40 IDF Unresponsive |
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| HereToGo wrote: |
| sled wrote: |
| stan_tichomirov wrote: |
Choke plunger missing or stuck open?
Stan |
Yup, that's what it was on my 40 idfs.
If you flip the carb over you can see the enrichment circuit port, I drilled and tapped it and ran some allen set screws to stop any future leaking |
I'll check on that, thanks. |
Update:
• Enrichment circuits are OK and closed
• Throttle shafts aren't bent or leaking
The carb is still not responding to mixture screws (open or closed) and pulling spark plug wires won't kill the cylinders.
Tried swapping carbs left to right and the problem followed the carb. Spits and sputters like it's lean (50 idle jets / 130 mains / 28 vents). If I pull spark plug wires on the 'good' carb, it kills the engine. There are no vacuum leaks.
Just thoroughly disassembled the carb and soaked it again and the idle circuits are still clean. It squirts fuel from both nozzles when opened.
The gasket at the top of the carb is good and not blocking the idle circuits.
Bottom line: one carb works, the other doesn't. Getting ready to put the single solex back on if I can't get this to work. |
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subhuman
Samba Member
Joined: January 22, 2008
Posts: 542
Location: north carolina
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| Posted: Fri Jun 03, 2016 12:31 pm Post subject: Re: 40 IDF Unresponsive |
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double check intake gasket at the head, chased a similar problem last year, turned out the gasket slid slightly when i put the intake on and had an air leak that did not show up when spraying starter fluid at it!
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stan_tichomirov
Samba Member
Joined: May 24, 2005
Posts: 1719
Location: San Francisco, CA
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| Posted: Fri Jun 03, 2016 12:54 pm Post subject: Re: 40 IDF Unresponsive |
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How about o-rings on the idle jet holder and idle mixture screw?
Stan
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HereToGo
Samba Member
Joined: April 17, 2001
Posts: 143
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| Posted: Fri Jun 03, 2016 2:16 pm Post subject: Re: 40 IDF Unresponsive |
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| stan_tichomirov wrote: |
How about o-rings on the idle jet holder and idle mixture screw?
Stan |
Yep, they're present.
Doesn't matter at this point, the POS setup is coming off and the Slo-lex is going back on. I'm done fiddle-farting with these touchy carbs. |
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madmike
Samba Member
Joined: July 11, 2005
Posts: 5302
Location: Atlanta,Michigan
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| Posted: Sat Jun 04, 2016 2:57 am Post subject: Re: 40 IDF Unresponsive |
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you have a plugged idle circuit,, compressed air will clear it
not a piddly little can of carb clearner,,  take it to,,, o never mind you want a stock POS carb,, that will give u piss poor mileage & performance
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HereToGo
Samba Member
Joined: April 17, 2001
Posts: 143
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| Posted: Sat Jun 04, 2016 7:54 am Post subject: Re: 40 IDF Unresponsive |
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| madmike wrote: |
you have a plugged idle circuit,, compressed air will clear it
not a piddly little can of carb clearner,, take it to,,, o never mind you want a stock POS carb,, that will give u piss poor mileage & performance |
I have blown compressed air through them after soaking them (5hp compressor) and can feel air moving through all of the passages, top and bottom.
Running out of options. I have worked with Kadrons, FRD's and 42 DCNF's, so this isn't my first rodeo with duals.
Open to other suggestions. |
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[email protected]
Samba Member
Joined: August 03, 2002
Posts: 12785
Location: Salt Lake City, Utah
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| Posted: Sat Jun 04, 2016 8:09 am Post subject: Re: 40 IDF Unresponsive |
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there are 2 circuits in the idle, the fuel circuit and the air circuit. You must make sure both are clear.
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chrisflstf
Samba Member
Joined: February 10, 2004
Posts: 4253
Location: San Diego
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| Posted: Sat Jun 04, 2016 8:31 am Post subject: Re: 40 IDF Unresponsive |
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| I would examine the idle jets under magnification. I had some that I repeatedly concluded were clean. If you looked at the hole, it was not round due to crap buildup that chemicals/compressed air would not remove. It took a fine wire brush to remove the deposit. Problem gone. You could swap idle jets from carb to carb as a test also |
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udidwht
Samba Member
Joined: March 06, 2005
Posts: 3804
Location: Seattle, WA./ HB, Ca./ Shizuoka, Japan
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| Posted: Tue Jun 07, 2016 12:00 am Post subject: Re: 40 IDF Unresponsive |
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Time for a leak down test.
But prior to that re check all the valves lash adjustment. Then recheck the mixture screw/s at idle.
You could also swap the carbs from side to side and see if the issue moves.
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Dual 40mm IDF Webers - LM-2 - 47.5 idles/125 mains/190 air corr./F11 tubes/28mm Vents - Float height 10.45mm/Drop 32mm
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HereToGo
Samba Member
Joined: April 17, 2001
Posts: 143
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| Posted: Mon Jun 27, 2016 1:19 pm Post subject: Re: 40 IDF Unresponsive |
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Found the problem and fixed it.
One of the four mixture screws was the wrong type (see illustration). After ordering the correct one, it runs properly now.
Bought the carbs used, so lesson learned, don't take anything for granted.
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sled
Samba Member
Joined: February 16, 2005
Posts: 6363
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| Posted: Mon Jun 27, 2016 5:06 pm Post subject: Re: 40 IDF Unresponsive |
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excellent resolution.
now are you happy you kept at it, and didn't regress to a stock carb?
that engine should run awesome with some 28 or 30 vents and proper jetting.
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