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daanbc
Samba Member
Joined: April 09, 2015
Posts: 403
Location: S.Fl
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 Posted: Mon Sep 14, 2015 7:37 pm Post subject: Flat spot explanation please? |
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| Ok, I have a 73 DP 1600 with a pict 34 dual exhaust and a Pertronix D186504 Flame-Thrower. I originally had a very bad flat spot. After the install of the dist. and correctly adjusting the carb. and timing. The buggy runs good. It actually runs GREAT when cold. But once warm, there is a "little" flat spot still. Nothing like was before, but enough to make you step on the accelerator a bit more to get the revs up to pass the flat spot when shifting. Is there ANYTHING that can be done to get rid of this for good?? |
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BL3Manx
Samba Member
Joined: August 29, 2006
Posts: 6768
Location: Northern California
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| Posted: Mon Sep 14, 2015 8:04 pm Post subject: |
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Is that a centrifugal advance, a vacuum advance or centrifugal/vacuum advance distributor?
Last edited by BL3Manx on Mon Sep 14, 2015 8:10 pm; edited 1 time in total |
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daanbc
Samba Member
Joined: April 09, 2015
Posts: 403
Location: S.Fl
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| Posted: Mon Sep 14, 2015 8:10 pm Post subject: |
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| BL3Manx wrote: |
| Is that a centrifugal advance, a vacuum advanve or centrifugal/vacuum advance distributor? |
Vacuum advance. |
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BL3Manx
Samba Member
Joined: August 29, 2006
Posts: 6768
Location: Northern California
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daanbc
Samba Member
Joined: April 09, 2015
Posts: 403
Location: S.Fl
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| Posted: Mon Sep 14, 2015 8:29 pm Post subject: |
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Thats funny, I just finished reading that, then saw your post to read it…… |
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BL3Manx
Samba Member
Joined: August 29, 2006
Posts: 6768
Location: Northern California
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| Posted: Mon Sep 14, 2015 8:36 pm Post subject: |
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| Some starter fluid sprayed around the manifold to head joint while idling should tell you if you have a leak |
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daanbc
Samba Member
Joined: April 09, 2015
Posts: 403
Location: S.Fl
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| Posted: Tue Sep 15, 2015 11:08 am Post subject: |
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| I took the carb off today and seen where the PO soldered in the hole on the plate. Because he was using a 009 diet. I replaced the diet. with a vacuum one. I am going to drill out the hole to see if this helps. |
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daanbc
Samba Member
Joined: April 09, 2015
Posts: 403
Location: S.Fl
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| Posted: Wed Sep 16, 2015 12:08 am Post subject: |
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After re-installing the carb, I noticed that the "barrel" that the accelerator cable connects to hits the side of the carb./manifold. Thus I was never getting full throttle. The most it would open was one third the way open. Also this was causing the whole bolt mechanism that the bottom plate attaches too, to become loose. At full throttle the barrel would cause the "bolt" to be pulled to the one side while trying to push/pass the carb./manifold. I'll have to grind/cut/shave off a little of the barrel so it will fit. This will help also with acceleration now. I thought it was under-powered for a 1600 DP.
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daanbc
Samba Member
Joined: April 09, 2015
Posts: 403
Location: S.Fl
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| Posted: Wed Sep 16, 2015 2:53 pm Post subject: |
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| Fixed the accelerator cable "barrel" Shaved a little off the end. Adjusted the cable (needed to be shorten a little) Now I have FULL Throttle. WOW what a difference. BUT now I still have a little bit of that flat spot, but ALSO a backfire pop or two when decelerating, when I push the clutch in to slow down, she pops every now and then once sometimes twice. Should I re-adjust the carb. settings again? I should note: just remembered I adjusted the accelerated pump too. I may have to place it back to its original position. I adjusted it to give more of a shot thinking it may help with the flat spot/hesitation. |
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