550 carbs on 750?

[cafe1253]

Hello everyone just like the title says can I use 550 carbs with the correst jets in them on a 750 engine?

There are some differences but not sure if it will work?

[cafe1253]

any suggestions?

[tkent02]

It would be able to run if you jetted it correctly. Probably not a lot of top end power but it may do OK. Getting the cylinder spacing correct might be a problem.

[hampshirehog]

Which 550 and which 750?

[ChicagoBob]

Clymer used to recommend the opposite: boring out the 550 and using 750 carbs.

[tkent02]

Clymer used to recommend the opposite: boring out the 550 and using 750 carbs.

This would give great top end power, might run a bit funny and be hard to tune for the slow stuff.

The OP didn't mention why he wanted to do this swap...

[tkent02]

Which 550 and which 750?

It use be the early ones, later on with CV carbs they used the same carburetor.

[Steve]

I will repeat the question, what year 550 and what year 750?

The earlier years (up through '79) used different carbs, so the 550 carbs would be a bit too small.

From '80 on, they used the same diameter, but the spacing was a bit different between carbs 2 and 3.

As you mentioned, though the jetting would have to be changed, too.

.

[cafe1253]

sorry it took me so long to respond I was in Texas on business. Anyways the 550 carbs are 81 and the 750 is an 79. Reason I want to do the change is the 750 carbs I have are reuined someone tried to drill out a jet and messed up the threads(on 3 of the 4 carbs). I have extra 550 carbs laying around so I can change the spacing with the 750 carb parts and use the 550 carbs. My issue is that the 550 carbs have smaller bore holes for the choke and send the fuel in differently for idle.

So back to my question will it work
thanks for all the help everyone

[Steve]

... the 550 carbs are 81 and the 750 is an 79. ...

So back to my question will it work

In a word, no.

OK, maybe, but it will take a LOT of work.

Like you have already noticed, the carbs are different diameters, so you will have to have adapters to narrow the 550 carbs (32mm throats) down to the 26mm intakes on the head. And don't forget that the 550 engine is narrower than the 750, so you will have to either spread the carbs apart or angle your adapters.

Overall, it will be MUCH easier to simply find a set of VM carbs for your 750.

.