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Author Topic: Cold start problem  (Read 1293 times)

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Offline slowrider

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Cold start problem
« on: July 19, 2009, 01:33:01 PM »
The 1977 CB750F2 I have a problem after being parked over night #4 carb seems to be empty of fuel. Cold start the exhaust is dead cold shake the bike a little the cylinder starts to come in after a minute then no problem until next cold start. This started about 2000 miles after complete carb rebuild
Has anyone heard of this?
Thanks   
Here are some pics as you can see the carbs were very clogged
http://s409.photobucket.com/albums/pp175/slowridercb750/
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Offline Spanner 1

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Re: Cold start problem
« Reply #1 on: July 19, 2009, 08:41:31 PM »
Hi, Slow, greetings from Gnashville!......If you park your bike on its side-stand I think the #4 carb, being the highest and at an angle, partially drains to the other carbs and leaves the idle/slow jet dry until the bowl fills again with fuel turned on and the bowl horizontal...IMO.
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If your sure it's a carb problem; it's ignition,
If your sure it's an ignition problem; it's carbs....

Offline the technological J

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Re: Cold start problem
« Reply #2 on: July 19, 2009, 08:51:14 PM »
ive heard of hair line cracks in the over flow tube... when running the leak might not keep up with the vaccum of the engine... does ur over flow have a tube running from it? check it when its running for fuel or leave ur pet cock on and see if it starts to drip(when not running).... just a guess
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70 KO...sold to fund the ST http://forums.sohc4.net/index.php?topic=88800.0(Alpha)
74 Kaw 250 Enduro http://forums.sohc4.net/index.php?topic=124278.0
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72 750 K2 Stay tuned!

Offline slowrider

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Re: Cold start problem
« Reply #3 on: July 19, 2009, 08:58:00 PM »
Spanner 1
I thought this also, but it does the same on center stand as well.
May be vent I don't know will check tomorrow. Thx for reply.

thegabrielj
No leaks or drips.

I have noticed flutter when on side stand idle at times possible fuel level. 
« Last Edit: July 19, 2009, 09:07:32 PM by slowrider »
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Offline Spanner 1

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Re: Cold start problem
« Reply #4 on: July 19, 2009, 09:13:20 PM »
Could be spark problem on #4, not carb related !, I would check the #4 plug wire to plug cap connection and swap 1 and 4 leads/caps to see if prob. moves to #1 cylinder.....
also if it happens when you lean the bike, plug wire shorting off head or frame ??
« Last Edit: July 19, 2009, 09:16:03 PM by Spanner 1 »
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If your sure it's a carb problem; it's ignition,
If your sure it's an ignition problem; it's carbs....

Offline slowrider

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Re: Cold start problem
« Reply #5 on: July 19, 2009, 09:21:41 PM »
Thx Spanner 1 another possibility. I tend to tunnel vision on some problems and can't get away from them.
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