Topic: PD44A carbs from a CB750A - Can I substitute PD46A carbs and swap jets?

[Yamahawk]

My friend Pat has been working on a set of PD44A carbs off of a CB750A engine that a fellow is making a 4-wheeler out of, and they are having a dickens of a time getting it to run correctly, as the idle solenoid isn't hooked up to the PD44's. There is a set of PD46A carbs that we swapped the jets into today, are they comparable to the PD44's and should they run well on a CB750A engine? The inlet and spigot to the engine are about the same size, and I think the PD46A's came from a CB550. Will there be any need to swap the pressed in pilot jets, as they don't seem to want to remove from the carb body, and is there any other consideration we might need to know about? The PD44's had an accelerator pump, the PD46A's do not have an accelerator pump...
Any thoughts would be greatly appreciated. Thanks!
Charlie

[Yamahawk]

Hondaman, oh Hondaman! Wherefore art thou, Brother?
Charlie

[seanbarney41]

Just swap on a set of cb750 roundtops...you know like you have on your bike?  Surely Pat has a pile of 'em hangin' around with the correct boots too.  That, I've heard, is good for a few extra ponies on the A's.  Roundtops are "the" Stone Axe of the motorcycle world.

Honestly don't know all the ramifications of the swap, as I have never messed with an A.

[Yamahawk]

Just swap on a set of cb750 roundtops...you know like you have on your bike?  Surely Pat has a pile of 'em hangin' around with the correct boots too.  That, I've heard, is good for a few extra ponies on the A's.  Roundtops are "the" Stone Axe of the motorcycle world.

Honestly don't know all the ramifications of the swap, as I have never messed with an A.

I know, that's what I told Pat also, but he already put the rebuild kits in the PD44A's, and didn't want to spend the extra $$ on 4 rebuild kits for the round tops. Personally, I would just clean them up really good, and they would probably be fine. The PD46A's he has are like new inside, and he just pulled the emulsion tubes and main out of the PD44A's and pu them in the PD46A's with the mixture needles also, along with the new springs, o-rings and teeny washers... lol. So, we have a set that would most likely work, as long as the pressed in jet isn't too small in the PD46A's. I guess the fellow can try them and see if they run better than the PD44A's as he couldn't get them to run right at all.
Tried to tell him to check the valves, and do the 3k tune up before he tries to get the carbs to run right, that could be the problem... Could be timing or valves instead.
Charlie

[ekpent]

 Don't know much about the automatics,never owned one but do know that stock they run smaller size carbs then the K's and F's.

[Yamahawk]

Don't know much about the automatics,never owned one but do know that stock they run smaller size carbs then the K's and F's.

I agree, and they are very close in size, if not identical, to the PD46A's used on the CB550's. That's why we were thinking that they might work. Takes the same jets, etc. and would fit the fellow's existing boots.
Charlie

[seanbarney41]

there is no reason to buy rebuild kits for round tops...ever, just make sure they are clean and the fuel t o-rings still seal.  That's all there is to it.