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Author Topic: 1979 CB650 brat style first build.  (Read 7876 times)

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Offline calj737

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Re: 1979 CB650 brat style first build.
« Reply #25 on: October 30, 2015, 06:14:28 AM »
Quote from: BollarNPS on October 29, 2015, 04:14:58 PM
i used a laser thermometer to check header temps and 1 3 4 are all between 110-115 and 2 is 95-100. what would cause this little difference in temp.
Most likely culprit is the #2 carb is slightly out of balance or A/F mixture with the others. It could be down to needing a vacuum synch, mixture screws, fuel level (floats) or worn innards.
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"Of all tyrannies, a tyranny sincerely exercised for the good of it's victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience." - C.S. Lewis

Offline BollarNPS

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Re: 1979 CB650 brat style first build.
« Reply #26 on: October 30, 2015, 07:29:20 AM »
silly me! yeah thats what ill be doing today is vaccum syncing it. The frame hoop is still unpainted and im redoing the battery box as metal and relocating to the center so still uncomplete pictures in a bit. Just dont wanna get to much more into the customizing till shes ridable. Carb four is still leaking fuel through the overflow and ive adjusted the float about as much as possible so im thinking its the neeedle tips rubber is to hard and just isnt working good enough.
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Offline calj737

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Re: 1979 CB650 brat style first build.
« Reply #27 on: October 30, 2015, 07:44:56 AM »
Quote from: BollarNPS on October 30, 2015, 07:29:20 AM
Carb four is still leaking fuel through the overflow and ive adjusted the float about as much as possible so im thinking its the neeedle tips rubber is to hard and just isnt working good enough.
Remove the bowl, fill it with fuel. Does it leak? If so, the overflow tube may be cracked and its not an indication of fuel level issues.
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"Of all tyrannies, a tyranny sincerely exercised for the good of it's victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience." - C.S. Lewis

Offline BollarNPS

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Re: 1979 CB650 brat style first build.
« Reply #28 on: October 30, 2015, 07:57:53 AM »
So I'm not great at welding so there is much more grinding to do but I'm gonna wait on that.




I'm not sure how to attach by the tank as it is obviously higher than everything else and I would like a flush fit.
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Offline calj737

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Re: 1979 CB650 brat style first build.
« Reply #29 on: October 30, 2015, 08:09:30 AM »
Well your pan needs to be shorter than it is to not interfere with the tank retaining bolt. That will create a large "gap" between the end of the tank and the seat, partly due to the style of seat, partly due to the configuration of the tank at the rear.

You could drill holes through the seat rail from underneath, then install a rivet nut into the pan, and screw the pan to the rail from below. Or do the same thing thru the cross brace at the mid point of the rails. Brat seats are tricky to mount in a clean and serviceable fashion.
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"Of all tyrannies, a tyranny sincerely exercised for the good of it's victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience." - C.S. Lewis

Offline BollarNPS

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Re: 1979 CB650 brat style first build.
« Reply #30 on: October 30, 2015, 08:16:00 AM »
Yeah it's a fuel issue it will stay full. Maybe I could cut a piece out of the pan so it fits around the tank mounting bracket?
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Offline swleathercraft

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Re: 1979 CB650 brat style first build.
« Reply #31 on: October 30, 2015, 11:29:05 AM »
Quote from: BollarNPS on October 30, 2015, 07:29:20 AM
silly me! yeah thats what ill be doing today is vaccum syncing it. The frame hoop is still unpainted and im redoing the battery box as metal and relocating to the center so still uncomplete pictures in a bit. Just dont wanna get to much more into the customizing till shes ridable. Carb four is still leaking fuel through the overflow and ive adjusted the float about as much as possible so im thinking its the neeedle tips rubber is to hard and just isnt working good enough.
I have this exact same problem on number 3 and 4 carbs on my 79 cb650. Still working it out.
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Offline Sgt.Pinback

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Re: 1979 CB650 brat style first build.
« Reply #32 on: October 30, 2015, 11:38:19 AM »
Thanks for sharing!
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Offline BollarNPS

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Re: 1979 CB650 brat style first build.
« Reply #33 on: October 30, 2015, 11:52:19 AM »
so for the Sgt. i just took the float out while it was still on the bike and replaced the float needle (not sure if thats the correct term) and this fixed the issue. When i rebuilt carbs i bought these but didnt change these as they seem to be in good condition. Try it out!
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Offline swleathercraft

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Re: 1979 CB650 brat style first build.
« Reply #34 on: October 31, 2015, 02:14:09 PM »
Ok it was the float needles. I replaced them and the problem is resolved


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