750 Zephyr carb flat spots

[Bonnylad]

Hi. Ongoing issues with two flat spots, one 3500rpm the other 6k rpm. new camshafts/chain, carbs re jetted, ultrasonic cleaned, you name it but still the same . Any help on this would be appresciated as it has been on going for a while now
Cheers BL.

[David Richard]

hi a couple years ago I put a stainless steel down pipes on my d1 which is in standard trim ,I found at about 2.500 to 3 k it had a flat spot just where you don't want it ,I have since removed it and put a genuine set on ,no flat spot ,what are your carb diaphrams like are they in good shape its all to do with the set up in the carb normally good luck ,david

[Freddy]

hi a couple years ago I put a stainless steel down pipes on my d1 which is in standard trim ,I found at about 2.500 to 3 k it had a flat spot just where you don't want it ,I have since removed it and put a genuine set on ,no flat spot ,what are your carb diaphrams like are they in good shape its all to do with the set up in the carb normally good luck ,david

Hi David,
Just curious, were the stainless pipes a 4:1 pattern or a 4:2 like the OEM pipes?

[David Richard]

morning freddy ,yes they are made in the uk called black widow exhausts its was a 4 into 2 with a balance pipe that just is in the wrong place to get the oil filter off easy,you had to fiddle about and get the bolt out first then you can get to it ,assembly was the tricky part but its in the loft now as a spare ,how did your ride go and the engine performed well ,david

[Freddy]

morning freddy ,yes they are made in the uk called black widow exhausts its was a 4 into 2 with a balance pipe that just is in the wrong place to get the oil filter off easy,you had to fiddle about and get the bolt out first then you can get to it ,assembly was the tricky part but its in the loft now as a spare ,how did your ride go and the engine performed well ,david

Ride was good, and engine running well. Still running it in with about 600 kilometers on it so far so haven't taken it much over 6000 rpm (IMO these engines only get going from 6000 onward). I'll wait till I have 1000 kilometers on it to let it free up, then see what it can really do.