Early carb vs late carb

[joe p]

I need a set of carbs for my 1973 CB750 parts bike that I'm trying to get back on the road. A guy I know has a set off a 1978/79 he will give me. He said the carbs are better then the old round top ones. Are they really a better carb?

 

[dirtdigger]

If he said 79 then he is lying because they didn't have sohc motor in 79 and with the switch to the dohc they went with cv carbs. 77/78 carbs are a bigger carb then the older carbs but they are slightly harder to do jetting. Pilot jets are pressed in on the later, early ones screw in and easy to change. Needle position is harder to change on later carbs. But later carbs have accel pump...but tend to go bad and plug with debri. You will also need to get different rubber boots from the head to the carb if using the later carbs because the carb is bigger. You will also need a different air filter setup as that side of the carb is also bigger. There may also be issues with the throttle cables fitting depending on year and if they are original cables or not. Better maybe...but not necessarily, If you want a drop in carb and not looking for any extra performance and want originality stay with the early carbs. The carbs may be free but the new boots depending on where you get them will cost you 80 to $100. You could take the free carbs and send them to me and I'll give you $20

 

[joe p]

It"s a 1978 SOHC 750 I don't know why he said 78/79. It's going to be a stock motor. I'm just trying to put something together as cheap as I can with all my junk parts

 

[dirtdigger]

Do you know if it is a k or an f2 carb set? If I was you I would take the carbs...because they are free, and sell them and buy some round tops if your original boots are good. If you need new boots anyway then run the later carbs. But you will need a different air filter setup.

 

[joe p]

I don't know if their K or F2. I have the boots on the 73. I will used them if I have to but I will keep looking for round top. Thanks