Topic: Cb750 Bog with throttle

[United.Cycles]

Fixed the high idle issue…. Now for the next issue.

74 cb750 - idles/revs fine in neutral…. Once in gear and given some throttle to ride, it bogs out. Is this an issue with the air mixture screws? Jets? Running 4-1 and uni filters. Tried both 45 slow 128 main and 42 slow 130 main with needle clip set one up from bottom. Almost positive the jets should be fine given my set up and elevation. I did mess with the mixture screws but can’t find the sweet spot if that is the issue. It ran fine before I removed the carbs to replace the idle adjustment screw because it was rusted stuck and snapped.


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[Jerry Rxman Griffin aka MuthaF'er]

IMO too fat on the bigs

[Finnigan]

biggest these came with from factory was 40 and 120 I believe, with the needle either in the 3rd or 4th position.

I'd go down to these and see if it improves, could also be like my recent discovery that electronic ignition sucks and limits revs

[willbird]

biggest these came with from factory was 40 and 120 I believe, with the needle either in the 3rd or 4th position.

I'd go down to these and see if it improves, could also be like my recent discovery that electronic ignition sucks and limits revs

I am running K&N and had UNI on recently, my 1972 CB750K has had 130 mains on the K&N and a Mac (and now a Delkevic) since 1995. Plugs looked on the lean side on the MAC, maybe a bit rich on the Delkevic but I have not done a proper plug chop to make sure my plug reading is just on the mains. My needles historically have been been lifted one notch from the middle spot. So 130 on pods is not a crazy thing by any means IMHO

[Finnigan]

Need more fuel for 4 into 1 exhaust?

The 'hot rod' sandcast 130mph machines ran 120s with larger airboxes and straight through pipes.  Could be you have a clogged air passage?

What ignition do you have installed?  Points?

[scottly]

It ran fine before I removed the carbs to replace the idle adjustment screw because it was rusted stuck and snapped.

If it ran fine before you removed the carbs, you must has messed something up. What was the issue with the high idle?