Cb750

[Marc Mcgowan]

I have a 1973 cb750 with pods an straight pipes pops backfires runs good at high rpm not good a idel an hesitates at low rpm any answers would be help full

 

[dan1951]

I,ve got a late 1971 that had pods on it, Ran like crap until I picked up all the parts to put the stock air box back on made a world of difference I also have Mac 4 into 4 pipes that I,m going to shitcan when I get some better 4 into 2 pipes. You have to have some back pressure to make them run right. I had it running half decent with the pods by messing with the jets but was not satisfied totally ran rich, Just My experience with PODS (piece of dung)

 

[dirtdigger]

Backpressure is not a good thing for an engine to work and produce power. Everyone assumes falls back to the "it needs a little backpressure" but in poor exhaust systems it is lack of a scavenge that makes them run poor and produce no power. If you have to build in backpressure to make an engine run you have issues with you total engine package. Short straight pipes will not make power at low rpm, they are high rpm pipes only. They will never run ideal at low rpm because of the lack of scavenge in the exhaust. The problem comes when you have a short inefficient 4 drag pipe exhaust then the pods on top and only trying to jet with jets and the needles. Everyone forgets about the cutout size and shape on the carb slide. There is so much more involved in jetting then people realize. Different taper of the needles, slide cutout size and shape, then you have jet sizes, emulsion tube sizing. When freeing up the exhaust and intake on the early 750 they like to have a couple of thousands taken off the bottom of the carb slides, but then this is a modification that can not be undone so should only be done when you get an exhaust and intake package that you plan on keeping. So yes you can get them jetted to where it will run good with pods and straight pipes but it will more than likely take more then just jets as most people do because they dont understand how the whole system works.

 

[amc49]

'You have to have some back pressure to make them run right.'

Complete and total MYTH. If so Nascar would be adding it to their engines and so would everybody drag racing in the country. Give that some thought.

OP, are you one of those who works on a 40 year old vehicle and thinks it's still in perfect condition? If so all the tuning in the universe will not help you. The straight pipes are a major strike against you as well.

Compression check just to make sure you aren't wasting all your time.......................